diff --git a/devops-stages/stage-test.sh b/devops-stages/stage-test.sh
index 693ca47..1e2f913 100755
--- a/devops-stages/stage-test.sh
+++ b/devops-stages/stage-test.sh
@@ -21,6 +21,7 @@
 # Execute tests for charms
 CHARM_PATH="./installers/charm"
 NEW_CHARMS_NAMES="osm-keystone osm-lcm osm-mon osm-nbi osm-ng-ui osm-pol osm-ro vca-integrator-operator"
+OLD_CHARMS_NAMES="prometheus grafana"
 for charm in $NEW_CHARMS_NAMES; do
     if [ $(git diff --name-only "origin/${GERRIT_BRANCH}" -- "installers/charm/${charm}" | wc -l) -ne 0 ]; then
         echo "Running tox for ${charm}"
@@ -29,6 +30,14 @@
         cd "${CURRENT_DIR}"
     fi
 done
+for charm in $OLD_CHARMS_NAMES; do
+    if [ $(git diff --name-only "origin/${GERRIT_BRANCH}" -- "installers/charm/${charm}" | wc -l) -ne 0 ]; then
+        echo "Running tox for ${charm}"
+        cd "${CHARM_PATH}/${charm}"
+        TOX_PARALLEL_NO_SPINNER=1 tox --parallel=auto
+        cd "${CURRENT_DIR}"
+    fi
+done
 
 # Execute linting test for OSM helm chart
 helm lint installers/helm/osm
diff --git a/installers/charm/prometheus/.gitignore b/installers/charm/prometheus/.gitignore
new file mode 100644
index 0000000..2885df2
--- /dev/null
+++ b/installers/charm/prometheus/.gitignore
@@ -0,0 +1,30 @@
+# Copyright 2021 Canonical Ltd.
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+#
+# For those usages not covered by the Apache License, Version 2.0 please
+# contact: legal@canonical.com
+#
+# To get in touch with the maintainers, please contact:
+# osm-charmers@lists.launchpad.net
+##
+
+venv
+.vscode
+build
+*.charm
+.coverage
+coverage.xml
+.stestr
+cover
+release
\ No newline at end of file
diff --git a/installers/charm/prometheus/.jujuignore b/installers/charm/prometheus/.jujuignore
new file mode 100644
index 0000000..3ae3e7d
--- /dev/null
+++ b/installers/charm/prometheus/.jujuignore
@@ -0,0 +1,34 @@
+# Copyright 2021 Canonical Ltd.
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+#
+# For those usages not covered by the Apache License, Version 2.0 please
+# contact: legal@canonical.com
+#
+# To get in touch with the maintainers, please contact:
+# osm-charmers@lists.launchpad.net
+##
+
+venv
+.vscode
+build
+*.charm
+.coverage
+coverage.xml
+.gitignore
+.stestr
+cover
+release
+tests/
+requirements*
+tox.ini
diff --git a/installers/charm/prometheus/.yamllint.yaml b/installers/charm/prometheus/.yamllint.yaml
new file mode 100644
index 0000000..d71fb69
--- /dev/null
+++ b/installers/charm/prometheus/.yamllint.yaml
@@ -0,0 +1,34 @@
+# Copyright 2021 Canonical Ltd.
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+#
+# For those usages not covered by the Apache License, Version 2.0 please
+# contact: legal@canonical.com
+#
+# To get in touch with the maintainers, please contact:
+# osm-charmers@lists.launchpad.net
+##
+
+---
+extends: default
+
+yaml-files:
+  - "*.yaml"
+  - "*.yml"
+  - ".yamllint"
+ignore: |
+  .tox
+  cover/
+  build/
+  venv
+  release/
diff --git a/installers/charm/prometheus/README.md b/installers/charm/prometheus/README.md
new file mode 100644
index 0000000..0486c0d
--- /dev/null
+++ b/installers/charm/prometheus/README.md
@@ -0,0 +1,23 @@
+<!-- Copyright 2021 Canonical Ltd.
+
+Licensed under the Apache License, Version 2.0 (the "License"); you may
+not use this file except in compliance with the License. You may obtain
+a copy of the License at
+
+        http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+License for the specific language governing permissions and limitations
+under the License.
+
+For those usages not covered by the Apache License, Version 2.0 please
+contact: legal@canonical.com
+
+To get in touch with the maintainers, please contact:
+osm-charmers@lists.launchpad.net -->
+
+# Prometheus operator Charm for Kubernetes
+
+## Requirements
diff --git a/installers/charm/prometheus/actions.yaml b/installers/charm/prometheus/actions.yaml
new file mode 100644
index 0000000..e41f3df
--- /dev/null
+++ b/installers/charm/prometheus/actions.yaml
@@ -0,0 +1,23 @@
+# Copyright 2021 Canonical Ltd.
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+#
+# For those usages not covered by the Apache License, Version 2.0 please
+# contact: legal@canonical.com
+#
+# To get in touch with the maintainers, please contact:
+# osm-charmers@lists.launchpad.net
+##
+
+backup:
+  description: "Do a mongodb backup"
diff --git a/installers/charm/prometheus/charmcraft.yaml b/installers/charm/prometheus/charmcraft.yaml
new file mode 100644
index 0000000..87d0463
--- /dev/null
+++ b/installers/charm/prometheus/charmcraft.yaml
@@ -0,0 +1,41 @@
+# Copyright 2021 Canonical Ltd.
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+#
+# For those usages not covered by the Apache License, Version 2.0 please
+# contact: legal@canonical.com
+#
+# To get in touch with the maintainers, please contact:
+# osm-charmers@lists.launchpad.net
+##
+
+type: charm
+bases:
+  - build-on:
+      - name: ubuntu
+        channel: "20.04"
+        architectures: ["amd64"]
+    run-on:
+      - name: ubuntu
+        channel: "20.04"
+        architectures:
+          - amd64
+          - aarch64
+          - arm64
+parts:
+  charm:
+    build-packages:
+      - cargo
+      - git
+      - libffi-dev
+      - rustc
diff --git a/installers/charm/prometheus/config.yaml b/installers/charm/prometheus/config.yaml
new file mode 100644
index 0000000..b25eaba
--- /dev/null
+++ b/installers/charm/prometheus/config.yaml
@@ -0,0 +1,85 @@
+# Copyright 2021 Canonical Ltd.
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+#
+# For those usages not covered by the Apache License, Version 2.0 please
+# contact: legal@canonical.com
+#
+# To get in touch with the maintainers, please contact:
+# osm-charmers@lists.launchpad.net
+##
+
+options:
+  web-subpath:
+    description: Subpath for accessing Prometheus
+    type: string
+    default: /
+  default-target:
+    description: Default target to be added in Prometheus
+    type: string
+    default: ""
+  max_file_size:
+    type: int
+    description: |
+      The maximum file size, in megabytes. If there is a reverse proxy in front
+      of Keystone, it may need to be configured to handle the requested size.
+      Note: if set to 0, there is no limit.
+    default: 0
+  ingress_class:
+    type: string
+    description: |
+      Ingress class name. This is useful for selecting the ingress to be used
+      in case there are multiple ingresses in the underlying k8s clusters.
+  ingress_whitelist_source_range:
+    type: string
+    description: |
+      A comma-separated list of CIDRs to store in the
+      ingress.kubernetes.io/whitelist-source-range annotation.
+
+      This can be used to lock down access to
+      Keystone based on source IP address.
+    default: ""
+  tls_secret_name:
+    type: string
+    description: TLS Secret name
+    default: ""
+  site_url:
+    type: string
+    description: Ingress URL
+    default: ""
+  cluster_issuer:
+    type: string
+    description: Name of the cluster issuer for TLS certificates
+    default: ""
+  enable_web_admin_api:
+    type: boolean
+    description: Boolean to enable the web admin api
+    default: false
+  image_pull_policy:
+    type: string
+    description: |
+      ImagePullPolicy configuration for the pod.
+      Possible values: always, ifnotpresent, never
+    default: always
+  security_context:
+    description: Enables the security context of the pods
+    type: boolean
+    default: false
+  web_config_username:
+    type: string
+    default: admin
+    description: Username to access the Prometheus Web Interface
+  web_config_password:
+    type: string
+    default: admin
+    description: Password to access the Prometheus Web Interface
diff --git a/installers/charm/prometheus/icon.svg b/installers/charm/prometheus/icon.svg
new file mode 100644
index 0000000..5c51f66
--- /dev/null
+++ b/installers/charm/prometheus/icon.svg
@@ -0,0 +1,50 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<!-- Generator: Adobe Illustrator 16.0.0, SVG Export Plug-In . SVG Version: 6.00 Build 0)  -->
+
+<svg
+   xmlns:dc="http://purl.org/dc/elements/1.1/"
+   xmlns:cc="http://creativecommons.org/ns#"
+   xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
+   xmlns:svg="http://www.w3.org/2000/svg"
+   xmlns="http://www.w3.org/2000/svg"
+   xmlns:sodipodi="http://sodipodi.sourceforge.net/DTD/sodipodi-0.dtd"
+   xmlns:inkscape="http://www.inkscape.org/namespaces/inkscape"
+   version="1.1"
+   id="Layer_1"
+   x="0px"
+   y="0px"
+   width="115.333px"
+   height="114px"
+   viewBox="0 0 115.333 114"
+   enable-background="new 0 0 115.333 114"
+   xml:space="preserve"
+   sodipodi:docname="prometheus_logo_orange.svg"
+   inkscape:version="0.92.1 r15371"><metadata
+     id="metadata4495"><rdf:RDF><cc:Work
+         rdf:about=""><dc:format>image/svg+xml</dc:format><dc:type
+           rdf:resource="http://purl.org/dc/dcmitype/StillImage" /><dc:title></dc:title></cc:Work></rdf:RDF></metadata><defs
+     id="defs4493" /><sodipodi:namedview
+     pagecolor="#ffffff"
+     bordercolor="#666666"
+     borderopacity="1"
+     objecttolerance="10"
+     gridtolerance="10"
+     guidetolerance="10"
+     inkscape:pageopacity="0"
+     inkscape:pageshadow="2"
+     inkscape:window-width="1484"
+     inkscape:window-height="886"
+     id="namedview4491"
+     showgrid="false"
+     inkscape:zoom="5.2784901"
+     inkscape:cx="60.603667"
+     inkscape:cy="60.329656"
+     inkscape:window-x="54"
+     inkscape:window-y="7"
+     inkscape:window-maximized="0"
+     inkscape:current-layer="Layer_1" /><g
+     id="Layer_2" /><path
+     style="fill:#e6522c;fill-opacity:1"
+     inkscape:connector-curvature="0"
+     id="path4486"
+     d="M 56.667,0.667 C 25.372,0.667 0,26.036 0,57.332 c 0,31.295 25.372,56.666 56.667,56.666 31.295,0 56.666,-25.371 56.666,-56.666 0,-31.296 -25.372,-56.665 -56.666,-56.665 z m 0,106.055 c -8.904,0 -16.123,-5.948 -16.123,-13.283 H 72.79 c 0,7.334 -7.219,13.283 -16.123,13.283 z M 83.297,89.04 H 30.034 V 79.382 H 83.298 V 89.04 Z M 83.106,74.411 H 30.186 C 30.01,74.208 29.83,74.008 29.66,73.802 24.208,67.182 22.924,63.726 21.677,60.204 c -0.021,-0.116 6.611,1.355 11.314,2.413 0,0 2.42,0.56 5.958,1.205 -3.397,-3.982 -5.414,-9.044 -5.414,-14.218 0,-11.359 8.712,-21.285 5.569,-29.308 3.059,0.249 6.331,6.456 6.552,16.161 3.252,-4.494 4.613,-12.701 4.613,-17.733 0,-5.21 3.433,-11.262 6.867,-11.469 -3.061,5.045 0.793,9.37 4.219,20.099 1.285,4.03 1.121,10.812 2.113,15.113 C 63.797,33.534 65.333,20.5 71,16 c -2.5,5.667 0.37,12.758 2.333,16.167 3.167,5.5 5.087,9.667 5.087,17.548 0,5.284 -1.951,10.259 -5.242,14.148 3.742,-0.702 6.326,-1.335 6.326,-1.335 l 12.152,-2.371 c 10e-4,-10e-4 -1.765,7.261 -8.55,14.254 z" /></svg>
\ No newline at end of file
diff --git a/installers/charm/prometheus/metadata.yaml b/installers/charm/prometheus/metadata.yaml
new file mode 100644
index 0000000..932ccc2
--- /dev/null
+++ b/installers/charm/prometheus/metadata.yaml
@@ -0,0 +1,51 @@
+# Copyright 2021 Canonical Ltd.
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+#
+# For those usages not covered by the Apache License, Version 2.0 please
+# contact: legal@canonical.com
+#
+# To get in touch with the maintainers, please contact:
+# osm-charmers@lists.launchpad.net
+##
+
+name: osm-prometheus
+summary: OSM Prometheus
+description: |
+  A CAAS charm to deploy OSM's Prometheus.
+series:
+  - kubernetes
+tags:
+  - kubernetes
+  - osm
+  - prometheus
+min-juju-version: 2.8.0
+deployment:
+  type: stateful
+  service: cluster
+resources:
+  backup-image:
+    type: oci-image
+    description: Container image to run backup actions
+    upstream-source: "ed1000/prometheus-backup:latest"
+  image:
+    type: oci-image
+    description: OSM docker image for Prometheus
+    upstream-source: "ubuntu/prometheus:latest"
+provides:
+  prometheus:
+    interface: prometheus
+storage:
+  data:
+    type: filesystem
+    location: /prometheus
diff --git a/installers/charm/prometheus/requirements-test.txt b/installers/charm/prometheus/requirements-test.txt
new file mode 100644
index 0000000..cf61dd4
--- /dev/null
+++ b/installers/charm/prometheus/requirements-test.txt
@@ -0,0 +1,20 @@
+# Copyright 2021 Canonical Ltd.
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+#
+# For those usages not covered by the Apache License, Version 2.0 please
+# contact: legal@canonical.com
+#
+# To get in touch with the maintainers, please contact:
+# osm-charmers@lists.launchpad.net
+mock==4.0.3
diff --git a/installers/charm/prometheus/requirements.txt b/installers/charm/prometheus/requirements.txt
new file mode 100644
index 0000000..db13e51
--- /dev/null
+++ b/installers/charm/prometheus/requirements.txt
@@ -0,0 +1,25 @@
+# Copyright 2021 Canonical Ltd.
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+#
+# For those usages not covered by the Apache License, Version 2.0 please
+# contact: legal@canonical.com
+#
+# To get in touch with the maintainers, please contact:
+# osm-charmers@lists.launchpad.net
+##
+
+git+https://github.com/charmed-osm/ops-lib-charmed-osm/@master
+requests
+urllib3>1.25.9
+bcrypt
diff --git a/installers/charm/prometheus/src/charm.py b/installers/charm/prometheus/src/charm.py
new file mode 100755
index 0000000..af39a13
--- /dev/null
+++ b/installers/charm/prometheus/src/charm.py
@@ -0,0 +1,298 @@
+#!/usr/bin/env python3
+# Copyright 2021 Canonical Ltd.
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+#
+# For those usages not covered by the Apache License, Version 2.0 please
+# contact: legal@canonical.com
+#
+# To get in touch with the maintainers, please contact:
+# osm-charmers@lists.launchpad.net
+##
+
+# pylint: disable=E0213
+
+import base64
+from ipaddress import ip_network
+import logging
+from typing import NoReturn, Optional
+from urllib.parse import urlparse
+
+import bcrypt
+from oci_image import OCIImageResource
+from ops.framework import EventBase
+from ops.main import main
+from opslib.osm.charm import CharmedOsmBase
+from opslib.osm.interfaces.prometheus import PrometheusServer
+from opslib.osm.pod import (
+    ContainerV3Builder,
+    FilesV3Builder,
+    IngressResourceV3Builder,
+    PodSpecV3Builder,
+)
+from opslib.osm.validator import (
+    ModelValidator,
+    validator,
+)
+import requests
+
+
+logger = logging.getLogger(__name__)
+
+PORT = 9090
+
+
+class ConfigModel(ModelValidator):
+    web_subpath: str
+    default_target: str
+    max_file_size: int
+    site_url: Optional[str]
+    cluster_issuer: Optional[str]
+    ingress_class: Optional[str]
+    ingress_whitelist_source_range: Optional[str]
+    tls_secret_name: Optional[str]
+    enable_web_admin_api: bool
+    image_pull_policy: str
+    security_context: bool
+    web_config_username: str
+    web_config_password: str
+
+    @validator("web_subpath")
+    def validate_web_subpath(cls, v):
+        if len(v) < 1:
+            raise ValueError("web-subpath must be a non-empty string")
+        return v
+
+    @validator("max_file_size")
+    def validate_max_file_size(cls, v):
+        if v < 0:
+            raise ValueError("value must be equal or greater than 0")
+        return v
+
+    @validator("site_url")
+    def validate_site_url(cls, v):
+        if v:
+            parsed = urlparse(v)
+            if not parsed.scheme.startswith("http"):
+                raise ValueError("value must start with http")
+        return v
+
+    @validator("ingress_whitelist_source_range")
+    def validate_ingress_whitelist_source_range(cls, v):
+        if v:
+            ip_network(v)
+        return v
+
+    @validator("image_pull_policy")
+    def validate_image_pull_policy(cls, v):
+        values = {
+            "always": "Always",
+            "ifnotpresent": "IfNotPresent",
+            "never": "Never",
+        }
+        v = v.lower()
+        if v not in values.keys():
+            raise ValueError("value must be always, ifnotpresent or never")
+        return values[v]
+
+
+class PrometheusCharm(CharmedOsmBase):
+
+    """Prometheus Charm."""
+
+    def __init__(self, *args) -> NoReturn:
+        """Prometheus Charm constructor."""
+        super().__init__(*args, oci_image="image")
+
+        # Registering provided relation events
+        self.prometheus = PrometheusServer(self, "prometheus")
+        self.framework.observe(
+            self.on.prometheus_relation_joined,  # pylint: disable=E1101
+            self._publish_prometheus_info,
+        )
+
+        # Registering actions
+        self.framework.observe(
+            self.on.backup_action,  # pylint: disable=E1101
+            self._on_backup_action,
+        )
+
+    def _publish_prometheus_info(self, event: EventBase) -> NoReturn:
+        config = ConfigModel(**dict(self.config))
+        self.prometheus.publish_info(
+            self.app.name,
+            PORT,
+            user=config.web_config_username,
+            password=config.web_config_password,
+        )
+
+    def _on_backup_action(self, event: EventBase) -> NoReturn:
+        url = f"http://{self.model.app.name}:{PORT}/api/v1/admin/tsdb/snapshot"
+        result = requests.post(url)
+
+        if result.status_code == 200:
+            event.set_results({"backup-name": result.json()["name"]})
+        else:
+            event.fail(f"status-code: {result.status_code}")
+
+    def _build_config_file(self, config: ConfigModel):
+        files_builder = FilesV3Builder()
+        files_builder.add_file(
+            "prometheus.yml",
+            (
+                "global:\n"
+                "  scrape_interval: 15s\n"
+                "  evaluation_interval: 15s\n"
+                "alerting:\n"
+                "  alertmanagers:\n"
+                "    - static_configs:\n"
+                "        - targets:\n"
+                "rule_files:\n"
+                "scrape_configs:\n"
+                "  - job_name: 'prometheus'\n"
+                "    static_configs:\n"
+                f"      - targets: [{config.default_target}]\n"
+            ),
+        )
+        return files_builder.build()
+
+    def _build_webconfig_file(self):
+        files_builder = FilesV3Builder()
+        files_builder.add_file("web.yml", "web-config-file", secret=True)
+        return files_builder.build()
+
+    def build_pod_spec(self, image_info):
+        # Validate config
+        config = ConfigModel(**dict(self.config))
+        # Create Builder for the PodSpec
+        pod_spec_builder = PodSpecV3Builder(
+            enable_security_context=config.security_context
+        )
+
+        # Build Backup Container
+        backup_image = OCIImageResource(self, "backup-image")
+        backup_image_info = backup_image.fetch()
+        backup_container_builder = ContainerV3Builder("prom-backup", backup_image_info)
+        backup_container = backup_container_builder.build()
+
+        # Add backup container to pod spec
+        pod_spec_builder.add_container(backup_container)
+
+        # Add pod secrets
+        prometheus_secret_name = f"{self.app.name}-secret"
+        pod_spec_builder.add_secret(
+            prometheus_secret_name,
+            {
+                "web-config-file": (
+                    "basic_auth_users:\n"
+                    f"  {config.web_config_username}: {self._hash_password(config.web_config_password)}\n"
+                )
+            },
+        )
+
+        # Build Container
+        container_builder = ContainerV3Builder(
+            self.app.name,
+            image_info,
+            config.image_pull_policy,
+            run_as_non_root=config.security_context,
+        )
+        container_builder.add_port(name=self.app.name, port=PORT)
+        token = self._base64_encode(
+            f"{config.web_config_username}:{config.web_config_password}"
+        )
+        container_builder.add_http_readiness_probe(
+            "/-/ready",
+            PORT,
+            initial_delay_seconds=10,
+            timeout_seconds=30,
+            http_headers=[("Authorization", f"Basic {token}")],
+        )
+        container_builder.add_http_liveness_probe(
+            "/-/healthy",
+            PORT,
+            initial_delay_seconds=30,
+            period_seconds=30,
+            http_headers=[("Authorization", f"Basic {token}")],
+        )
+        command = [
+            "/bin/prometheus",
+            "--config.file=/etc/prometheus/prometheus.yml",
+            "--web.config.file=/etc/prometheus/web-config/web.yml",
+            "--storage.tsdb.path=/prometheus",
+            "--web.console.libraries=/usr/share/prometheus/console_libraries",
+            "--web.console.templates=/usr/share/prometheus/consoles",
+            f"--web.route-prefix={config.web_subpath}",
+            f"--web.external-url=http://localhost:{PORT}{config.web_subpath}",
+        ]
+        if config.enable_web_admin_api:
+            command.append("--web.enable-admin-api")
+        container_builder.add_command(command)
+        container_builder.add_volume_config(
+            "config", "/etc/prometheus", self._build_config_file(config)
+        )
+        container_builder.add_volume_config(
+            "web-config",
+            "/etc/prometheus/web-config",
+            self._build_webconfig_file(),
+            secret_name=prometheus_secret_name,
+        )
+        container = container_builder.build()
+        # Add container to pod spec
+        pod_spec_builder.add_container(container)
+        # Add ingress resources to pod spec if site url exists
+        if config.site_url:
+            parsed = urlparse(config.site_url)
+            annotations = {
+                "nginx.ingress.kubernetes.io/proxy-body-size": "{}".format(
+                    str(config.max_file_size) + "m"
+                    if config.max_file_size > 0
+                    else config.max_file_size
+                )
+            }
+            if config.ingress_class:
+                annotations["kubernetes.io/ingress.class"] = config.ingress_class
+            ingress_resource_builder = IngressResourceV3Builder(
+                f"{self.app.name}-ingress", annotations
+            )
+
+            if config.ingress_whitelist_source_range:
+                annotations[
+                    "nginx.ingress.kubernetes.io/whitelist-source-range"
+                ] = config.ingress_whitelist_source_range
+
+            if config.cluster_issuer:
+                annotations["cert-manager.io/cluster-issuer"] = config.cluster_issuer
+
+            if parsed.scheme == "https":
+                ingress_resource_builder.add_tls(
+                    [parsed.hostname], config.tls_secret_name
+                )
+            else:
+                annotations["nginx.ingress.kubernetes.io/ssl-redirect"] = "false"
+
+            ingress_resource_builder.add_rule(parsed.hostname, self.app.name, PORT)
+            ingress_resource = ingress_resource_builder.build()
+            pod_spec_builder.add_ingress_resource(ingress_resource)
+        return pod_spec_builder.build()
+
+    def _hash_password(self, password):
+        hashed_password = bcrypt.hashpw(password.encode("utf-8"), bcrypt.gensalt())
+        return hashed_password.decode()
+
+    def _base64_encode(self, phrase: str) -> str:
+        return base64.b64encode(phrase.encode("utf-8")).decode("utf-8")
+
+
+if __name__ == "__main__":
+    main(PrometheusCharm)
diff --git a/installers/charm/prometheus/src/pod_spec.py b/installers/charm/prometheus/src/pod_spec.py
new file mode 100644
index 0000000..202114e
--- /dev/null
+++ b/installers/charm/prometheus/src/pod_spec.py
@@ -0,0 +1,380 @@
+#!/usr/bin/env python3
+# Copyright 2021 Canonical Ltd.
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+#
+# For those usages not covered by the Apache License, Version 2.0 please
+# contact: legal@canonical.com
+#
+# To get in touch with the maintainers, please contact:
+# osm-charmers@lists.launchpad.net
+##
+
+from ipaddress import ip_network
+import logging
+from typing import Any, Dict, List
+from urllib.parse import urlparse
+
+logger = logging.getLogger(__name__)
+
+
+def _validate_max_file_size(max_file_size: int, site_url: str) -> bool:
+    """Validate max_file_size.
+
+    Args:
+        max_file_size (int): maximum file size allowed.
+        site_url (str): endpoint url.
+
+    Returns:
+        bool: True if valid, false otherwise.
+    """
+    if not site_url:
+        return True
+
+    parsed = urlparse(site_url)
+
+    if not parsed.scheme.startswith("http"):
+        return True
+
+    if max_file_size is None:
+        return False
+
+    return max_file_size >= 0
+
+
+def _validate_ip_network(network: str) -> bool:
+    """Validate IP network.
+
+    Args:
+        network (str): IP network range.
+
+    Returns:
+        bool: True if valid, false otherwise.
+    """
+    if not network:
+        return True
+
+    try:
+        ip_network(network)
+    except ValueError:
+        return False
+
+    return True
+
+
+def _validate_data(config_data: Dict[str, Any], relation_data: Dict[str, Any]) -> bool:
+    """Validates passed information.
+
+    Args:
+        config_data (Dict[str, Any]): configuration information.
+        relation_data (Dict[str, Any]): relation information
+
+    Raises:
+        ValueError: when config and/or relation data is not valid.
+    """
+    config_validators = {
+        "web_subpath": lambda value, _: isinstance(value, str) and len(value) > 0,
+        "default_target": lambda value, _: isinstance(value, str),
+        "site_url": lambda value, _: isinstance(value, str)
+        if value is not None
+        else True,
+        "max_file_size": lambda value, values: _validate_max_file_size(
+            value, values.get("site_url")
+        ),
+        "ingress_whitelist_source_range": lambda value, _: _validate_ip_network(value),
+        "tls_secret_name": lambda value, _: isinstance(value, str)
+        if value is not None
+        else True,
+        "enable_web_admin_api": lambda value, _: isinstance(value, bool),
+    }
+    relation_validators = {}
+    problems = []
+
+    for key, validator in config_validators.items():
+        valid = validator(config_data.get(key), config_data)
+
+        if not valid:
+            problems.append(key)
+
+    for key, validator in relation_validators.items():
+        valid = validator(relation_data.get(key), relation_data)
+
+        if not valid:
+            problems.append(key)
+
+    if len(problems) > 0:
+        raise ValueError("Errors found in: {}".format(", ".join(problems)))
+
+    return True
+
+
+def _make_pod_ports(port: int) -> List[Dict[str, Any]]:
+    """Generate pod ports details.
+
+    Args:
+        port (int): port to expose.
+
+    Returns:
+        List[Dict[str, Any]]: pod port details.
+    """
+    return [{"name": "prometheus", "containerPort": port, "protocol": "TCP"}]
+
+
+def _make_pod_envconfig(
+    config: Dict[str, Any], relation_state: Dict[str, Any]
+) -> Dict[str, Any]:
+    """Generate pod environment configuration.
+
+    Args:
+        config (Dict[str, Any]): configuration information.
+        relation_state (Dict[str, Any]): relation state information.
+
+    Returns:
+        Dict[str, Any]: pod environment configuration.
+    """
+    envconfig = {}
+
+    return envconfig
+
+
+def _make_pod_ingress_resources(
+    config: Dict[str, Any], app_name: str, port: int
+) -> List[Dict[str, Any]]:
+    """Generate pod ingress resources.
+
+    Args:
+        config (Dict[str, Any]): configuration information.
+        app_name (str): application name.
+        port (int): port to expose.
+
+    Returns:
+        List[Dict[str, Any]]: pod ingress resources.
+    """
+    site_url = config.get("site_url")
+
+    if not site_url:
+        return
+
+    parsed = urlparse(site_url)
+
+    if not parsed.scheme.startswith("http"):
+        return
+
+    max_file_size = config["max_file_size"]
+    ingress_whitelist_source_range = config["ingress_whitelist_source_range"]
+
+    annotations = {
+        "nginx.ingress.kubernetes.io/proxy-body-size": "{}".format(
+            str(max_file_size) + "m" if max_file_size > 0 else max_file_size
+        ),
+    }
+
+    if ingress_whitelist_source_range:
+        annotations[
+            "nginx.ingress.kubernetes.io/whitelist-source-range"
+        ] = ingress_whitelist_source_range
+
+    ingress_spec_tls = None
+
+    if parsed.scheme == "https":
+        ingress_spec_tls = [{"hosts": [parsed.hostname]}]
+        tls_secret_name = config["tls_secret_name"]
+        if tls_secret_name:
+            ingress_spec_tls[0]["secretName"] = tls_secret_name
+    else:
+        annotations["nginx.ingress.kubernetes.io/ssl-redirect"] = "false"
+
+    ingress = {
+        "name": "{}-ingress".format(app_name),
+        "annotations": annotations,
+        "spec": {
+            "rules": [
+                {
+                    "host": parsed.hostname,
+                    "http": {
+                        "paths": [
+                            {
+                                "path": "/",
+                                "backend": {
+                                    "serviceName": app_name,
+                                    "servicePort": port,
+                                },
+                            }
+                        ]
+                    },
+                }
+            ]
+        },
+    }
+    if ingress_spec_tls:
+        ingress["spec"]["tls"] = ingress_spec_tls
+
+    return [ingress]
+
+
+def _make_pod_files(config: Dict[str, Any]) -> List[Dict[str, Any]]:
+    """Generating ConfigMap information
+
+    Args:
+        config (Dict[str, Any]): configuration information.
+
+    Returns:
+        List[Dict[str, Any]]: ConfigMap information.
+    """
+    files = [
+        {
+            "name": "config",
+            "mountPath": "/etc/prometheus",
+            "files": [
+                {
+                    "path": "prometheus.yml",
+                    "content": (
+                        "global:\n"
+                        "  scrape_interval: 15s\n"
+                        "  evaluation_interval: 15s\n"
+                        "alerting:\n"
+                        "  alertmanagers:\n"
+                        "    - static_configs:\n"
+                        "        - targets:\n"
+                        "rule_files:\n"
+                        "scrape_configs:\n"
+                        "  - job_name: 'prometheus'\n"
+                        "    static_configs:\n"
+                        "      - targets: [{}]\n".format(config["default_target"])
+                    ),
+                }
+            ],
+        }
+    ]
+
+    return files
+
+
+def _make_readiness_probe(port: int) -> Dict[str, Any]:
+    """Generate readiness probe.
+
+    Args:
+        port (int): service port.
+
+    Returns:
+        Dict[str, Any]: readiness probe.
+    """
+    return {
+        "httpGet": {
+            "path": "/-/ready",
+            "port": port,
+        },
+        "initialDelaySeconds": 10,
+        "timeoutSeconds": 30,
+    }
+
+
+def _make_liveness_probe(port: int) -> Dict[str, Any]:
+    """Generate liveness probe.
+
+    Args:
+        port (int): service port.
+
+    Returns:
+        Dict[str, Any]: liveness probe.
+    """
+    return {
+        "httpGet": {
+            "path": "/-/healthy",
+            "port": port,
+        },
+        "initialDelaySeconds": 30,
+        "periodSeconds": 30,
+    }
+
+
+def _make_pod_command(config: Dict[str, Any], port: int) -> List[str]:
+    """Generate the startup command.
+
+    Args:
+        config (Dict[str, Any]): Configuration information.
+        port (int): port.
+
+    Returns:
+        List[str]: command to startup the process.
+    """
+    command = [
+        "/bin/prometheus",
+        "--config.file=/etc/prometheus/prometheus.yml",
+        "--storage.tsdb.path=/prometheus",
+        "--web.console.libraries=/usr/share/prometheus/console_libraries",
+        "--web.console.templates=/usr/share/prometheus/consoles",
+        "--web.route-prefix={}".format(config.get("web_subpath")),
+        "--web.external-url=http://localhost:{}{}".format(
+            port, config.get("web_subpath")
+        ),
+    ]
+    if config.get("enable_web_admin_api"):
+        command.append("--web.enable-admin-api")
+    return command
+
+
+def make_pod_spec(
+    image_info: Dict[str, str],
+    config: Dict[str, Any],
+    relation_state: Dict[str, Any],
+    app_name: str = "prometheus",
+    port: int = 9090,
+) -> Dict[str, Any]:
+    """Generate the pod spec information.
+
+    Args:
+        image_info (Dict[str, str]): Object provided by
+            OCIImageResource("image").fetch().
+        config (Dict[str, Any]): Configuration information.
+        relation_state (Dict[str, Any]): Relation state information.
+        app_name (str, optional): Application name. Defaults to "ro".
+        port (int, optional): Port for the container. Defaults to 9090.
+
+    Returns:
+        Dict[str, Any]: Pod spec dictionary for the charm.
+    """
+    if not image_info:
+        return None
+
+    _validate_data(config, relation_state)
+
+    ports = _make_pod_ports(port)
+    env_config = _make_pod_envconfig(config, relation_state)
+    files = _make_pod_files(config)
+    readiness_probe = _make_readiness_probe(port)
+    liveness_probe = _make_liveness_probe(port)
+    ingress_resources = _make_pod_ingress_resources(config, app_name, port)
+    command = _make_pod_command(config, port)
+
+    return {
+        "version": 3,
+        "containers": [
+            {
+                "name": app_name,
+                "imageDetails": image_info,
+                "imagePullPolicy": "Always",
+                "ports": ports,
+                "envConfig": env_config,
+                "volumeConfig": files,
+                "command": command,
+                "kubernetes": {
+                    "readinessProbe": readiness_probe,
+                    "livenessProbe": liveness_probe,
+                },
+            }
+        ],
+        "kubernetesResources": {
+            "ingressResources": ingress_resources or [],
+        },
+    }
diff --git a/installers/charm/prometheus/tests/__init__.py b/installers/charm/prometheus/tests/__init__.py
new file mode 100644
index 0000000..446d5ce
--- /dev/null
+++ b/installers/charm/prometheus/tests/__init__.py
@@ -0,0 +1,40 @@
+#!/usr/bin/env python3
+# Copyright 2020 Canonical Ltd.
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+#
+# For those usages not covered by the Apache License, Version 2.0 please
+# contact: legal@canonical.com
+#
+# To get in touch with the maintainers, please contact:
+# osm-charmers@lists.launchpad.net
+##
+
+"""Init mocking for unit tests."""
+
+import sys
+
+
+import mock
+
+
+class OCIImageResourceErrorMock(Exception):
+    pass
+
+
+sys.path.append("src")
+
+oci_image = mock.MagicMock()
+oci_image.OCIImageResourceError = OCIImageResourceErrorMock
+sys.modules["oci_image"] = oci_image
+sys.modules["oci_image"].OCIImageResource().fetch.return_value = {}
diff --git a/installers/charm/prometheus/tests/test_charm.py b/installers/charm/prometheus/tests/test_charm.py
new file mode 100644
index 0000000..965400a
--- /dev/null
+++ b/installers/charm/prometheus/tests/test_charm.py
@@ -0,0 +1,111 @@
+#!/usr/bin/env python3
+# Copyright 2020 Canonical Ltd.
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+#
+# For those usages not covered by the Apache License, Version 2.0 please
+# contact: legal@canonical.com
+#
+# To get in touch with the maintainers, please contact:
+# osm-charmers@lists.launchpad.net
+##
+
+import sys
+from typing import NoReturn
+import unittest
+
+from charm import PrometheusCharm
+from ops.model import ActiveStatus
+from ops.testing import Harness
+
+
+class TestCharm(unittest.TestCase):
+    """Prometheus Charm unit tests."""
+
+    def setUp(self) -> NoReturn:
+        """Test setup"""
+        self.image_info = sys.modules["oci_image"].OCIImageResource().fetch()
+        self.harness = Harness(PrometheusCharm)
+        self.harness.set_leader(is_leader=True)
+        self.harness.begin()
+        self.config = {
+            "web-subpath": "/",
+            "default-target": "",
+            "max_file_size": 0,
+            "ingress_whitelist_source_range": "",
+            "tls_secret_name": "",
+            "site_url": "https://prometheus.192.168.100.100.nip.io",
+            "cluster_issuer": "vault-issuer",
+            "enable_web_admin_api": False,
+            "web_config_username": "admin",
+            "web_config_password": "1234",
+        }
+        self.harness.update_config(self.config)
+
+    def test_config_changed(
+        self,
+    ) -> NoReturn:
+        """Test ingress resources without HTTP."""
+
+        self.harness.charm.on.config_changed.emit()
+
+        # Assertions
+        self.assertIsInstance(self.harness.charm.unit.status, ActiveStatus)
+
+    def test_config_changed_non_leader(
+        self,
+    ) -> NoReturn:
+        """Test ingress resources without HTTP."""
+        self.harness.set_leader(is_leader=False)
+        self.harness.charm.on.config_changed.emit()
+
+        # Assertions
+        self.assertIsInstance(self.harness.charm.unit.status, ActiveStatus)
+
+    def test_publish_prometheus_info(
+        self,
+    ) -> NoReturn:
+        """Test to see if prometheus relation is updated."""
+        expected_result = {
+            "hostname": self.harness.charm.app.name,
+            "port": "9090",
+            "user": "admin",
+            "password": "1234",
+        }
+
+        relation_id = self.harness.add_relation("prometheus", "mon")
+        self.harness.add_relation_unit(relation_id, "mon/0")
+        relation_data = self.harness.get_relation_data(
+            relation_id, self.harness.charm.app.name
+        )
+
+        self.assertDictEqual(expected_result, relation_data)
+
+    def test_publish_prometheus_info_non_leader(
+        self,
+    ) -> NoReturn:
+        """Test to see if prometheus relation is updated."""
+        expected_result = {}
+
+        self.harness.set_leader(is_leader=False)
+        relation_id = self.harness.add_relation("prometheus", "mon")
+        self.harness.add_relation_unit(relation_id, "mon/0")
+        relation_data = self.harness.get_relation_data(
+            relation_id, self.harness.charm.app.name
+        )
+
+        self.assertDictEqual(expected_result, relation_data)
+
+
+if __name__ == "__main__":
+    unittest.main()
diff --git a/installers/charm/prometheus/tests/test_pod_spec.py b/installers/charm/prometheus/tests/test_pod_spec.py
new file mode 100644
index 0000000..1adbae6
--- /dev/null
+++ b/installers/charm/prometheus/tests/test_pod_spec.py
@@ -0,0 +1,640 @@
+#!/usr/bin/env python3
+# Copyright 2020 Canonical Ltd.
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+#
+# For those usages not covered by the Apache License, Version 2.0 please
+# contact: legal@canonical.com
+#
+# To get in touch with the maintainers, please contact:
+# osm-charmers@lists.launchpad.net
+##
+
+from typing import NoReturn
+import unittest
+
+import pod_spec
+
+
+class TestPodSpec(unittest.TestCase):
+    """Pod spec unit tests."""
+
+    def test_make_pod_ports(self) -> NoReturn:
+        """Testing make pod ports."""
+        port = 9090
+
+        expected_result = [
+            {
+                "name": "prometheus",
+                "containerPort": port,
+                "protocol": "TCP",
+            }
+        ]
+
+        pod_ports = pod_spec._make_pod_ports(port)
+
+        self.assertListEqual(expected_result, pod_ports)
+
+    def test_make_pod_envconfig(self) -> NoReturn:
+        """Testing make pod envconfig."""
+        config = {}
+        relation_state = {}
+
+        expected_result = {}
+
+        pod_envconfig = pod_spec._make_pod_envconfig(config, relation_state)
+
+        self.assertDictEqual(expected_result, pod_envconfig)
+
+    def test_make_pod_ingress_resources_without_site_url(self) -> NoReturn:
+        """Testing make pod ingress resources without site_url."""
+        config = {"site_url": ""}
+        app_name = "prometheus"
+        port = 9090
+
+        pod_ingress_resources = pod_spec._make_pod_ingress_resources(
+            config, app_name, port
+        )
+
+        self.assertIsNone(pod_ingress_resources)
+
+    def test_make_pod_ingress_resources(self) -> NoReturn:
+        """Testing make pod ingress resources."""
+        config = {
+            "site_url": "http://prometheus",
+            "max_file_size": 0,
+            "ingress_whitelist_source_range": "",
+        }
+        app_name = "prometheus"
+        port = 9090
+
+        expected_result = [
+            {
+                "name": f"{app_name}-ingress",
+                "annotations": {
+                    "nginx.ingress.kubernetes.io/proxy-body-size": f"{config['max_file_size']}",
+                    "nginx.ingress.kubernetes.io/ssl-redirect": "false",
+                },
+                "spec": {
+                    "rules": [
+                        {
+                            "host": app_name,
+                            "http": {
+                                "paths": [
+                                    {
+                                        "path": "/",
+                                        "backend": {
+                                            "serviceName": app_name,
+                                            "servicePort": port,
+                                        },
+                                    }
+                                ]
+                            },
+                        }
+                    ]
+                },
+            }
+        ]
+
+        pod_ingress_resources = pod_spec._make_pod_ingress_resources(
+            config, app_name, port
+        )
+
+        self.assertListEqual(expected_result, pod_ingress_resources)
+
+    def test_make_pod_ingress_resources_with_whitelist_source_range(self) -> NoReturn:
+        """Testing make pod ingress resources with whitelist_source_range."""
+        config = {
+            "site_url": "http://prometheus",
+            "max_file_size": 0,
+            "ingress_whitelist_source_range": "0.0.0.0/0",
+        }
+        app_name = "prometheus"
+        port = 9090
+
+        expected_result = [
+            {
+                "name": f"{app_name}-ingress",
+                "annotations": {
+                    "nginx.ingress.kubernetes.io/proxy-body-size": f"{config['max_file_size']}",
+                    "nginx.ingress.kubernetes.io/ssl-redirect": "false",
+                    "nginx.ingress.kubernetes.io/whitelist-source-range": config[
+                        "ingress_whitelist_source_range"
+                    ],
+                },
+                "spec": {
+                    "rules": [
+                        {
+                            "host": app_name,
+                            "http": {
+                                "paths": [
+                                    {
+                                        "path": "/",
+                                        "backend": {
+                                            "serviceName": app_name,
+                                            "servicePort": port,
+                                        },
+                                    }
+                                ]
+                            },
+                        }
+                    ]
+                },
+            }
+        ]
+
+        pod_ingress_resources = pod_spec._make_pod_ingress_resources(
+            config, app_name, port
+        )
+
+        self.assertListEqual(expected_result, pod_ingress_resources)
+
+    def test_make_pod_ingress_resources_with_https(self) -> NoReturn:
+        """Testing make pod ingress resources with HTTPs."""
+        config = {
+            "site_url": "https://prometheus",
+            "max_file_size": 0,
+            "ingress_whitelist_source_range": "",
+            "tls_secret_name": "",
+        }
+        app_name = "prometheus"
+        port = 9090
+
+        expected_result = [
+            {
+                "name": f"{app_name}-ingress",
+                "annotations": {
+                    "nginx.ingress.kubernetes.io/proxy-body-size": f"{config['max_file_size']}",
+                },
+                "spec": {
+                    "rules": [
+                        {
+                            "host": app_name,
+                            "http": {
+                                "paths": [
+                                    {
+                                        "path": "/",
+                                        "backend": {
+                                            "serviceName": app_name,
+                                            "servicePort": port,
+                                        },
+                                    }
+                                ]
+                            },
+                        }
+                    ],
+                    "tls": [{"hosts": [app_name]}],
+                },
+            }
+        ]
+
+        pod_ingress_resources = pod_spec._make_pod_ingress_resources(
+            config, app_name, port
+        )
+
+        self.assertListEqual(expected_result, pod_ingress_resources)
+
+    def test_make_pod_ingress_resources_with_https_tls_secret_name(self) -> NoReturn:
+        """Testing make pod ingress resources with HTTPs and TLS secret name."""
+        config = {
+            "site_url": "https://prometheus",
+            "max_file_size": 0,
+            "ingress_whitelist_source_range": "",
+            "tls_secret_name": "secret_name",
+        }
+        app_name = "prometheus"
+        port = 9090
+
+        expected_result = [
+            {
+                "name": f"{app_name}-ingress",
+                "annotations": {
+                    "nginx.ingress.kubernetes.io/proxy-body-size": f"{config['max_file_size']}",
+                },
+                "spec": {
+                    "rules": [
+                        {
+                            "host": app_name,
+                            "http": {
+                                "paths": [
+                                    {
+                                        "path": "/",
+                                        "backend": {
+                                            "serviceName": app_name,
+                                            "servicePort": port,
+                                        },
+                                    }
+                                ]
+                            },
+                        }
+                    ],
+                    "tls": [
+                        {"hosts": [app_name], "secretName": config["tls_secret_name"]}
+                    ],
+                },
+            }
+        ]
+
+        pod_ingress_resources = pod_spec._make_pod_ingress_resources(
+            config, app_name, port
+        )
+
+        self.assertListEqual(expected_result, pod_ingress_resources)
+
+    def test_make_pod_files(self) -> NoReturn:
+        """Testing make pod files."""
+        config = {
+            "web_subpath": "/",
+            "default_target": "",
+            "site_url": "",
+        }
+
+        expected_result = [
+            {
+                "name": "config",
+                "mountPath": "/etc/prometheus",
+                "files": [
+                    {
+                        "path": "prometheus.yml",
+                        "content": (
+                            "global:\n"
+                            "  scrape_interval: 15s\n"
+                            "  evaluation_interval: 15s\n"
+                            "alerting:\n"
+                            "  alertmanagers:\n"
+                            "    - static_configs:\n"
+                            "        - targets:\n"
+                            "rule_files:\n"
+                            "scrape_configs:\n"
+                            "  - job_name: 'prometheus'\n"
+                            "    static_configs:\n"
+                            "      - targets: [{}]\n".format(config["default_target"])
+                        ),
+                    }
+                ],
+            }
+        ]
+
+        pod_envconfig = pod_spec._make_pod_files(config)
+        self.assertListEqual(expected_result, pod_envconfig)
+
+    def test_make_readiness_probe(self) -> NoReturn:
+        """Testing make readiness probe."""
+        port = 9090
+
+        expected_result = {
+            "httpGet": {
+                "path": "/-/ready",
+                "port": port,
+            },
+            "initialDelaySeconds": 10,
+            "timeoutSeconds": 30,
+        }
+
+        readiness_probe = pod_spec._make_readiness_probe(port)
+
+        self.assertDictEqual(expected_result, readiness_probe)
+
+    def test_make_liveness_probe(self) -> NoReturn:
+        """Testing make liveness probe."""
+        port = 9090
+
+        expected_result = {
+            "httpGet": {
+                "path": "/-/healthy",
+                "port": port,
+            },
+            "initialDelaySeconds": 30,
+            "periodSeconds": 30,
+        }
+
+        liveness_probe = pod_spec._make_liveness_probe(port)
+
+        self.assertDictEqual(expected_result, liveness_probe)
+
+    def test_make_pod_command(self) -> NoReturn:
+        """Testing make pod command."""
+        port = 9090
+        config = {
+            "web_subpath": "/",
+            "default_target": "",
+            "site_url": "",
+        }
+
+        expected_result = [
+            "/bin/prometheus",
+            "--config.file=/etc/prometheus/prometheus.yml",
+            "--storage.tsdb.path=/prometheus",
+            "--web.console.libraries=/usr/share/prometheus/console_libraries",
+            "--web.console.templates=/usr/share/prometheus/consoles",
+            "--web.route-prefix={}".format(config.get("web_subpath")),
+            "--web.external-url=http://localhost:{}{}".format(
+                port, config.get("web_subpath")
+            ),
+        ]
+
+        pod_envconfig = pod_spec._make_pod_command(config, port)
+
+        self.assertListEqual(expected_result, pod_envconfig)
+
+    def test_make_pod_command_with_web_admin_api_enabled(self) -> NoReturn:
+        """Testing make pod command."""
+        port = 9090
+        config = {
+            "web_subpath": "/",
+            "default_target": "",
+            "site_url": "",
+            "enable_web_admin_api": True,
+        }
+
+        expected_result = [
+            "/bin/prometheus",
+            "--config.file=/etc/prometheus/prometheus.yml",
+            "--storage.tsdb.path=/prometheus",
+            "--web.console.libraries=/usr/share/prometheus/console_libraries",
+            "--web.console.templates=/usr/share/prometheus/consoles",
+            "--web.route-prefix={}".format(config.get("web_subpath")),
+            "--web.external-url=http://localhost:{}{}".format(
+                port, config.get("web_subpath")
+            ),
+            "--web.enable-admin-api",
+        ]
+
+        pod_envconfig = pod_spec._make_pod_command(config, port)
+
+        self.assertListEqual(expected_result, pod_envconfig)
+
+    def test_make_pod_spec(self) -> NoReturn:
+        """Testing make pod spec."""
+        image_info = {"upstream-source": "ubuntu/prometheus:latest"}
+        config = {
+            "web_subpath": "/",
+            "default_target": "",
+            "site_url": "",
+            "enable_web_admin_api": False,
+        }
+        relation_state = {}
+        app_name = "prometheus"
+        port = 9090
+
+        expected_result = {
+            "version": 3,
+            "containers": [
+                {
+                    "name": app_name,
+                    "imageDetails": image_info,
+                    "imagePullPolicy": "Always",
+                    "ports": [
+                        {
+                            "name": app_name,
+                            "containerPort": port,
+                            "protocol": "TCP",
+                        }
+                    ],
+                    "envConfig": {},
+                    "volumeConfig": [
+                        {
+                            "name": "config",
+                            "mountPath": "/etc/prometheus",
+                            "files": [
+                                {
+                                    "path": "prometheus.yml",
+                                    "content": (
+                                        "global:\n"
+                                        "  scrape_interval: 15s\n"
+                                        "  evaluation_interval: 15s\n"
+                                        "alerting:\n"
+                                        "  alertmanagers:\n"
+                                        "    - static_configs:\n"
+                                        "        - targets:\n"
+                                        "rule_files:\n"
+                                        "scrape_configs:\n"
+                                        "  - job_name: 'prometheus'\n"
+                                        "    static_configs:\n"
+                                        "      - targets: [{}]\n".format(
+                                            config.get("default_target")
+                                        )
+                                    ),
+                                }
+                            ],
+                        }
+                    ],
+                    "command": [
+                        "/bin/prometheus",
+                        "--config.file=/etc/prometheus/prometheus.yml",
+                        "--storage.tsdb.path=/prometheus",
+                        "--web.console.libraries=/usr/share/prometheus/console_libraries",
+                        "--web.console.templates=/usr/share/prometheus/consoles",
+                        "--web.route-prefix={}".format(config.get("web_subpath")),
+                        "--web.external-url=http://localhost:{}{}".format(
+                            port, config.get("web_subpath")
+                        ),
+                    ],
+                    "kubernetes": {
+                        "readinessProbe": {
+                            "httpGet": {
+                                "path": "/-/ready",
+                                "port": port,
+                            },
+                            "initialDelaySeconds": 10,
+                            "timeoutSeconds": 30,
+                        },
+                        "livenessProbe": {
+                            "httpGet": {
+                                "path": "/-/healthy",
+                                "port": port,
+                            },
+                            "initialDelaySeconds": 30,
+                            "periodSeconds": 30,
+                        },
+                    },
+                }
+            ],
+            "kubernetesResources": {"ingressResources": []},
+        }
+
+        spec = pod_spec.make_pod_spec(
+            image_info, config, relation_state, app_name, port
+        )
+
+        self.assertDictEqual(expected_result, spec)
+
+    def test_make_pod_spec_with_ingress(self) -> NoReturn:
+        """Testing make pod spec."""
+        image_info = {"upstream-source": "ubuntu/prometheus:latest"}
+        config = {
+            "web_subpath": "/",
+            "default_target": "",
+            "site_url": "https://prometheus",
+            "tls_secret_name": "prometheus",
+            "max_file_size": 0,
+            "ingress_whitelist_source_range": "0.0.0.0/0",
+            "enable_web_admin_api": False,
+        }
+        relation_state = {}
+        app_name = "prometheus"
+        port = 9090
+
+        expected_result = {
+            "version": 3,
+            "containers": [
+                {
+                    "name": app_name,
+                    "imageDetails": image_info,
+                    "imagePullPolicy": "Always",
+                    "ports": [
+                        {
+                            "name": app_name,
+                            "containerPort": port,
+                            "protocol": "TCP",
+                        }
+                    ],
+                    "envConfig": {},
+                    "volumeConfig": [
+                        {
+                            "name": "config",
+                            "mountPath": "/etc/prometheus",
+                            "files": [
+                                {
+                                    "path": "prometheus.yml",
+                                    "content": (
+                                        "global:\n"
+                                        "  scrape_interval: 15s\n"
+                                        "  evaluation_interval: 15s\n"
+                                        "alerting:\n"
+                                        "  alertmanagers:\n"
+                                        "    - static_configs:\n"
+                                        "        - targets:\n"
+                                        "rule_files:\n"
+                                        "scrape_configs:\n"
+                                        "  - job_name: 'prometheus'\n"
+                                        "    static_configs:\n"
+                                        "      - targets: [{}]\n".format(
+                                            config.get("default_target")
+                                        )
+                                    ),
+                                }
+                            ],
+                        }
+                    ],
+                    "command": [
+                        "/bin/prometheus",
+                        "--config.file=/etc/prometheus/prometheus.yml",
+                        "--storage.tsdb.path=/prometheus",
+                        "--web.console.libraries=/usr/share/prometheus/console_libraries",
+                        "--web.console.templates=/usr/share/prometheus/consoles",
+                        "--web.route-prefix={}".format(config.get("web_subpath")),
+                        "--web.external-url=http://localhost:{}{}".format(
+                            port, config.get("web_subpath")
+                        ),
+                    ],
+                    "kubernetes": {
+                        "readinessProbe": {
+                            "httpGet": {
+                                "path": "/-/ready",
+                                "port": port,
+                            },
+                            "initialDelaySeconds": 10,
+                            "timeoutSeconds": 30,
+                        },
+                        "livenessProbe": {
+                            "httpGet": {
+                                "path": "/-/healthy",
+                                "port": port,
+                            },
+                            "initialDelaySeconds": 30,
+                            "periodSeconds": 30,
+                        },
+                    },
+                }
+            ],
+            "kubernetesResources": {
+                "ingressResources": [
+                    {
+                        "name": "{}-ingress".format(app_name),
+                        "annotations": {
+                            "nginx.ingress.kubernetes.io/proxy-body-size": str(
+                                config.get("max_file_size")
+                            ),
+                            "nginx.ingress.kubernetes.io/whitelist-source-range": config.get(
+                                "ingress_whitelist_source_range"
+                            ),
+                        },
+                        "spec": {
+                            "rules": [
+                                {
+                                    "host": app_name,
+                                    "http": {
+                                        "paths": [
+                                            {
+                                                "path": "/",
+                                                "backend": {
+                                                    "serviceName": app_name,
+                                                    "servicePort": port,
+                                                },
+                                            }
+                                        ]
+                                    },
+                                }
+                            ],
+                            "tls": [
+                                {
+                                    "hosts": [app_name],
+                                    "secretName": config.get("tls_secret_name"),
+                                }
+                            ],
+                        },
+                    }
+                ],
+            },
+        }
+
+        spec = pod_spec.make_pod_spec(
+            image_info, config, relation_state, app_name, port
+        )
+
+        self.assertDictEqual(expected_result, spec)
+
+    def test_make_pod_spec_without_image_info(self) -> NoReturn:
+        """Testing make pod spec without image_info."""
+        image_info = None
+        config = {
+            "web_subpath": "/",
+            "default_target": "",
+            "site_url": "",
+            "enable_web_admin_api": False,
+        }
+        relation_state = {}
+        app_name = "prometheus"
+        port = 9090
+
+        spec = pod_spec.make_pod_spec(
+            image_info, config, relation_state, app_name, port
+        )
+
+        self.assertIsNone(spec)
+
+    def test_make_pod_spec_without_config(self) -> NoReturn:
+        """Testing make pod spec without config."""
+        image_info = {"upstream-source": "ubuntu/prometheus:latest"}
+        config = {}
+        relation_state = {}
+        app_name = "prometheus"
+        port = 9090
+
+        with self.assertRaises(ValueError):
+            pod_spec.make_pod_spec(image_info, config, relation_state, app_name, port)
+
+
+if __name__ == "__main__":
+    unittest.main()
diff --git a/installers/charm/prometheus/tox.ini b/installers/charm/prometheus/tox.ini
new file mode 100644
index 0000000..4c7970d
--- /dev/null
+++ b/installers/charm/prometheus/tox.ini
@@ -0,0 +1,126 @@
+# Copyright 2021 Canonical Ltd.
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+#
+# For those usages not covered by the Apache License, Version 2.0 please
+# contact: legal@canonical.com
+#
+# To get in touch with the maintainers, please contact:
+# osm-charmers@lists.launchpad.net
+##
+#######################################################################################
+
+[tox]
+envlist = black, cover, flake8, pylint, yamllint, safety
+skipsdist = true
+
+[tox:jenkins]
+toxworkdir = /tmp/.tox
+
+[testenv]
+basepython = python3.8
+setenv = VIRTUAL_ENV={envdir}
+         PYTHONDONTWRITEBYTECODE = 1
+deps =  -r{toxinidir}/requirements.txt
+
+
+#######################################################################################
+[testenv:black]
+deps = black
+commands =
+        black --check --diff src/ tests/
+
+
+#######################################################################################
+[testenv:cover]
+deps =  {[testenv]deps}
+        -r{toxinidir}/requirements-test.txt
+        coverage
+        nose2
+commands =
+        sh -c 'rm -f nosetests.xml'
+        coverage erase
+        nose2 -C --coverage src
+        coverage report --omit='*tests*'
+        coverage html -d ./cover --omit='*tests*'
+        coverage xml -o coverage.xml --omit=*tests*
+whitelist_externals = sh
+
+
+#######################################################################################
+[testenv:flake8]
+deps =  flake8
+        flake8-import-order
+commands =
+        flake8 src/ tests/
+
+
+#######################################################################################
+[testenv:pylint]
+deps =  {[testenv]deps}
+        -r{toxinidir}/requirements-test.txt
+        pylint==2.10.2
+commands =
+    pylint -E src/ tests/
+
+
+#######################################################################################
+[testenv:safety]
+setenv =
+        LC_ALL=C.UTF-8
+        LANG=C.UTF-8
+deps =  {[testenv]deps}
+        safety
+commands =
+        - safety check --full-report
+
+
+#######################################################################################
+[testenv:yamllint]
+deps =  {[testenv]deps}
+        -r{toxinidir}/requirements-test.txt
+        yamllint
+commands = yamllint .
+
+#######################################################################################
+[testenv:build]
+passenv=HTTP_PROXY HTTPS_PROXY NO_PROXY
+whitelist_externals =
+  charmcraft
+  sh
+commands =
+  charmcraft pack
+  sh -c 'ubuntu_version=20.04; \
+        architectures="amd64-aarch64-arm64"; \
+        charm_name=`cat metadata.yaml | grep -E "^name: " | cut -f 2 -d " "`; \
+        mv $charm_name"_ubuntu-"$ubuntu_version-$architectures.charm $charm_name.charm'
+
+#######################################################################################
+[flake8]
+ignore =
+        W291,
+        W293,
+        W503,
+        E123,
+        E125,
+        E226,
+        E241,
+exclude =
+        .git,
+        __pycache__,
+        .tox,
+max-line-length = 120
+show-source = True
+builtins = _
+max-complexity = 10
+import-order-style = google