diff --git a/installers/charm/osm-update-db-operator/.gitignore b/installers/charm/osm-update-db-operator/.gitignore
new file mode 100644
index 0000000..c250157
--- /dev/null
+++ b/installers/charm/osm-update-db-operator/.gitignore
@@ -0,0 +1,23 @@
+# Copyright 2022 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.
+
+venv/
+build/
+*.charm
+.coverage
+coverage.xml
+__pycache__/
+*.py[cod]
+.vscode
+.tox
diff --git a/installers/charm/osm-update-db-operator/.jujuignore b/installers/charm/osm-update-db-operator/.jujuignore
new file mode 100644
index 0000000..ddb544e
--- /dev/null
+++ b/installers/charm/osm-update-db-operator/.jujuignore
@@ -0,0 +1,17 @@
+# Copyright 2022 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.
+
+/venv
+*.py[cod]
+*.charm
diff --git a/installers/charm/osm-update-db-operator/CONTRIBUTING.md b/installers/charm/osm-update-db-operator/CONTRIBUTING.md
new file mode 100644
index 0000000..4d70671
--- /dev/null
+++ b/installers/charm/osm-update-db-operator/CONTRIBUTING.md
@@ -0,0 +1,74 @@
+<!-- Copyright 2022 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.
+-->
+# Contributing
+
+## Overview
+
+This documents explains the processes and practices recommended for contributing enhancements to
+the Update DB charm.
+
+- Generally, before developing enhancements to this charm, you should consider [opening an issue
+  ](https://github.com/gcalvinos/update-db-operator/issues) explaining your use case.
+- If you would like to chat with us about your use-cases or proposed implementation, you can reach
+  us at [Canonical Mattermost public channel](https://chat.charmhub.io/charmhub/channels/charm-dev)
+  or [Discourse](https://discourse.charmhub.io/). The primary author of this charm is available on
+  the Mattermost channel as `@davigar15`.
+- Familiarising yourself with the [Charmed Operator Framework](https://juju.is/docs/sdk) library
+  will help you a lot when working on new features or bug fixes.
+- All enhancements require review before being merged. Code review typically examines
+  - code quality
+  - test coverage
+  - user experience for Juju administrators this charm.
+- Please help us out in ensuring easy to review branches by rebasing your pull request branch onto
+  the `main` branch. This also avoids merge commits and creates a linear Git commit history.
+
+## Developing
+
+You can use the environments created by `tox` for development:
+
+```shell
+tox --notest -e unit
+source .tox/unit/bin/activate
+```
+
+### Testing
+
+```shell
+tox -e fmt           # update your code according to linting rules
+tox -e lint          # code style
+tox -e unit          # unit tests
+# tox -e integration   # integration tests
+tox                  # runs 'lint' and 'unit' environments
+```
+
+## Build charm
+
+Build the charm in this git repository using:
+
+```shell
+charmcraft pack
+```
+
+### Deploy
+
+```bash
+# Create a model
+juju add-model test-update-db
+# Enable DEBUG logging
+juju model-config logging-config="<root>=INFO;unit=DEBUG"
+# Deploy the charm
+juju deploy ./update-db_ubuntu-20.04-amd64.charm \
+  --resource update-db-image=ubuntu:latest
+```
diff --git a/installers/charm/osm-update-db-operator/LICENSE b/installers/charm/osm-update-db-operator/LICENSE
new file mode 100644
index 0000000..d645695
--- /dev/null
+++ b/installers/charm/osm-update-db-operator/LICENSE
@@ -0,0 +1,202 @@
+
+                                 Apache License
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+
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+       http://www.apache.org/licenses/LICENSE-2.0
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+   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.
diff --git a/installers/charm/osm-update-db-operator/README.md b/installers/charm/osm-update-db-operator/README.md
new file mode 100644
index 0000000..2ee8f6e
--- /dev/null
+++ b/installers/charm/osm-update-db-operator/README.md
@@ -0,0 +1,80 @@
+<!-- Copyright 2022 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.
+-->
+
+# OSM Update DB Operator
+
+[![code style](https://img.shields.io/badge/code%20style-black-000000.svg)](https://github.com/psf/black/tree/main)
+
+## Description
+
+Charm used to update the OSM databases during an OSM upgrade process. To be used you should have an instance of OSM running that you may want to upgrade
+
+## Usage
+
+### Deploy the charm (locally)
+
+```shell
+juju add-model update-db
+juju deploy osm-update-db-operator --series focal
+```
+
+Set MongoDB and MySQL URIs:
+
+```shell
+juju config osm-update-db-operator mysql-uri=<mysql_uri>
+juju config osm-update-db-operator mongodb-uri=<mongodb_uri>
+```
+
+### Updating the databases
+
+In case we want to update both databases, we need to run the following command:
+
+```shell
+juju run-action osm-update-db-operator/0 update-db current-version=<Number_of_current_version> target-version=<Number_of_target_version>
+# Example:
+juju run-action osm-update-db-operator/0 update-db current-version=9 target-version=10
+```
+
+In case only you just want to update MongoDB, then we can use a flag 'mongodb-only=True':
+
+```shell
+juju run-action osm-update-db-operator/0 update-db current-version=9 target-version=10 mongodb-only=True
+```
+
+In case only you just want to update MySQL database, then we can use a flag 'mysql-only=True':
+
+```shell
+juju run-action osm-update-db-operator/0 update-db current-version=9 target-version=10 mysql-only=True
+```
+
+You can check if the update of the database was properly done checking the result of the command:
+
+```shell
+juju show-action-output <Number_of_the_action>
+```
+
+### Fixes for bugs
+
+Updates de database to apply the changes needed to fix a bug. You need to specify the bug number. Example:
+
+```shell
+juju run-action osm-update-db-operator/0 apply-patch bug-number=1837
+```
+
+## Contributing
+
+Please see the [Juju SDK docs](https://juju.is/docs/sdk) for guidelines
+on enhancements to this charm following best practice guidelines, and
+`CONTRIBUTING.md` for developer guidance.
diff --git a/installers/charm/osm-update-db-operator/actions.yaml b/installers/charm/osm-update-db-operator/actions.yaml
new file mode 100644
index 0000000..aba1ee3
--- /dev/null
+++ b/installers/charm/osm-update-db-operator/actions.yaml
@@ -0,0 +1,42 @@
+# Copyright 2022 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.
+
+update-db:
+  description: |
+    Updates the Mongodb and MySQL with the new data needed for the target OSM
+  params:
+    current-version:
+      type: integer
+      description: "Current version of Charmed OSM - Example: 9"
+    target-version:
+      type: integer
+      description: "Final version of OSM after the update - Example: 10"
+    mysql-only:
+      type: boolean
+      description: "if True the update is only applied for mysql database"
+    mongodb-only:
+      type: boolean
+      description: "if True the update is only applied for mongo database"
+  required:
+    - current-version
+    - target-version
+apply-patch:
+  description: |
+    Updates de database to apply the changes needed to fix a bug
+  params:
+    bug-number:
+      type: integer
+      description: "The number of the bug that needs to be fixed"
+  required:
+    - bug-number
diff --git a/installers/charm/osm-update-db-operator/charmcraft.yaml b/installers/charm/osm-update-db-operator/charmcraft.yaml
new file mode 100644
index 0000000..31c233b
--- /dev/null
+++ b/installers/charm/osm-update-db-operator/charmcraft.yaml
@@ -0,0 +1,26 @@
+# Copyright 2022 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.
+
+type: "charm"
+bases:
+  - build-on:
+      - name: "ubuntu"
+        channel: "20.04"
+    run-on:
+      - name: "ubuntu"
+        channel: "20.04"
+parts:
+  charm:
+    build-packages:
+      - git
diff --git a/installers/charm/osm-update-db-operator/config.yaml b/installers/charm/osm-update-db-operator/config.yaml
new file mode 100644
index 0000000..3b7190b
--- /dev/null
+++ b/installers/charm/osm-update-db-operator/config.yaml
@@ -0,0 +1,29 @@
+# Copyright 2022 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.
+
+options:
+  log-level:
+    description: "Log Level"
+    type: string
+    default: "INFO"
+  mongodb-uri:
+    type: string
+    description: |
+      MongoDB URI (external database)
+      mongodb://<mongo_host>:<mongo_port>/
+  mysql-uri:
+    type: string
+    description: |
+      Mysql URI with the following format:
+        mysql://<user>:<password>@<mysql_host>:<mysql_port>/<database>
diff --git a/installers/charm/osm-update-db-operator/metadata.yaml b/installers/charm/osm-update-db-operator/metadata.yaml
new file mode 100644
index 0000000..b058591
--- /dev/null
+++ b/installers/charm/osm-update-db-operator/metadata.yaml
@@ -0,0 +1,19 @@
+# Copyright 2022 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.
+
+name: osm-update-db-operator
+description: |
+  Charm to update the OSM databases
+summary: |
+  Charm to update the OSM databases
diff --git a/installers/charm/osm-update-db-operator/pyproject.toml b/installers/charm/osm-update-db-operator/pyproject.toml
new file mode 100644
index 0000000..3fae174
--- /dev/null
+++ b/installers/charm/osm-update-db-operator/pyproject.toml
@@ -0,0 +1,53 @@
+# Copyright 2022 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.
+
+# Testing tools configuration
+[tool.coverage.run]
+branch = true
+
+[tool.coverage.report]
+show_missing = true
+
+[tool.pytest.ini_options]
+minversion = "6.0"
+log_cli_level = "INFO"
+
+# Formatting tools configuration
+[tool.black]
+line-length = 99
+target-version = ["py38"]
+
+[tool.isort]
+profile = "black"
+
+# Linting tools configuration
+[tool.flake8]
+max-line-length = 99
+max-doc-length = 99
+max-complexity = 10
+exclude = [".git", "__pycache__", ".tox", "build", "dist", "*.egg_info", "venv"]
+select = ["E", "W", "F", "C", "N", "R", "D", "H"]
+# Ignore W503, E501 because using black creates errors with this
+# Ignore D107 Missing docstring in __init__
+ignore = ["W503", "E501", "D107"]
+# D100, D101, D102, D103: Ignore missing docstrings in tests
+per-file-ignores = ["tests/*:D100,D101,D102,D103,D104"]
+docstring-convention = "google"
+# Check for properly formatted copyright header in each file
+copyright-check = "True"
+copyright-author = "Canonical Ltd."
+copyright-regexp = "Copyright\\s\\d{4}([-,]\\d{4})*\\s+%(author)s"
+
+[tool.bandit]
+tests = ["B201", "B301"]
diff --git a/installers/charm/osm-update-db-operator/requirements.txt b/installers/charm/osm-update-db-operator/requirements.txt
new file mode 100644
index 0000000..b488dba
--- /dev/null
+++ b/installers/charm/osm-update-db-operator/requirements.txt
@@ -0,0 +1,16 @@
+# Copyright 2022 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.
+
+ops < 2.2
+pymongo == 3.12.3
diff --git a/installers/charm/osm-update-db-operator/src/charm.py b/installers/charm/osm-update-db-operator/src/charm.py
new file mode 100755
index 0000000..32db2f7
--- /dev/null
+++ b/installers/charm/osm-update-db-operator/src/charm.py
@@ -0,0 +1,119 @@
+#!/usr/bin/env python3
+# Copyright 2022 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.
+
+"""Update DB charm module."""
+
+import logging
+
+from ops.charm import CharmBase
+from ops.framework import StoredState
+from ops.main import main
+from ops.model import ActiveStatus, BlockedStatus
+
+from db_upgrade import MongoUpgrade, MysqlUpgrade
+
+logger = logging.getLogger(__name__)
+
+
+class UpgradeDBCharm(CharmBase):
+    """Upgrade DB Charm operator."""
+
+    _stored = StoredState()
+
+    def __init__(self, *args):
+        super().__init__(*args)
+
+        # Observe events
+        event_observe_mapping = {
+            self.on.update_db_action: self._on_update_db_action,
+            self.on.apply_patch_action: self._on_apply_patch_action,
+            self.on.config_changed: self._on_config_changed,
+        }
+        for event, observer in event_observe_mapping.items():
+            self.framework.observe(event, observer)
+
+    @property
+    def mongo(self):
+        """Create MongoUpgrade object if the configuration has been set."""
+        mongo_uri = self.config.get("mongodb-uri")
+        return MongoUpgrade(mongo_uri) if mongo_uri else None
+
+    @property
+    def mysql(self):
+        """Create MysqlUpgrade object if the configuration has been set."""
+        mysql_uri = self.config.get("mysql-uri")
+        return MysqlUpgrade(mysql_uri) if mysql_uri else None
+
+    def _on_config_changed(self, _):
+        mongo_uri = self.config.get("mongodb-uri")
+        mysql_uri = self.config.get("mysql-uri")
+        if not mongo_uri and not mysql_uri:
+            self.unit.status = BlockedStatus("mongodb-uri and/or mysql-uri must be set")
+            return
+        self.unit.status = ActiveStatus()
+
+    def _on_update_db_action(self, event):
+        """Handle the update-db action."""
+        current_version = str(event.params["current-version"])
+        target_version = str(event.params["target-version"])
+        mysql_only = event.params.get("mysql-only")
+        mongodb_only = event.params.get("mongodb-only")
+        try:
+            results = {}
+            if mysql_only and mongodb_only:
+                raise Exception("cannot set both mysql-only and mongodb-only options to True")
+            if mysql_only:
+                self._upgrade_mysql(current_version, target_version)
+                results["mysql"] = "Upgraded successfully"
+            elif mongodb_only:
+                self._upgrade_mongodb(current_version, target_version)
+                results["mongodb"] = "Upgraded successfully"
+            else:
+                self._upgrade_mysql(current_version, target_version)
+                results["mysql"] = "Upgraded successfully"
+                self._upgrade_mongodb(current_version, target_version)
+                results["mongodb"] = "Upgraded successfully"
+            event.set_results(results)
+        except Exception as e:
+            event.fail(f"Failed DB Upgrade: {e}")
+
+    def _upgrade_mysql(self, current_version, target_version):
+        logger.debug("Upgrading mysql")
+        if self.mysql:
+            self.mysql.upgrade(current_version, target_version)
+        else:
+            raise Exception("mysql-uri not set")
+
+    def _upgrade_mongodb(self, current_version, target_version):
+        logger.debug("Upgrading mongodb")
+        if self.mongo:
+            self.mongo.upgrade(current_version, target_version)
+        else:
+            raise Exception("mongo-uri not set")
+
+    def _on_apply_patch_action(self, event):
+        bug_number = event.params["bug-number"]
+        logger.debug("Patching bug number {}".format(str(bug_number)))
+        try:
+            if self.mongo:
+                self.mongo.apply_patch(bug_number)
+            else:
+                raise Exception("mongo-uri not set")
+        except Exception as e:
+            event.fail(f"Failed Patch Application: {e}")
+
+
+if __name__ == "__main__":  # pragma: no cover
+    main(UpgradeDBCharm, use_juju_for_storage=True)
diff --git a/installers/charm/osm-update-db-operator/src/db_upgrade.py b/installers/charm/osm-update-db-operator/src/db_upgrade.py
new file mode 100644
index 0000000..05cc0a0
--- /dev/null
+++ b/installers/charm/osm-update-db-operator/src/db_upgrade.py
@@ -0,0 +1,275 @@
+# Copyright 2022 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.
+
+"""Upgrade DB charm module."""
+
+import json
+import logging
+
+from pymongo import MongoClient
+
+logger = logging.getLogger(__name__)
+
+
+class MongoUpgrade1012:
+    """Upgrade MongoDB Database from OSM v10 to v12."""
+
+    @staticmethod
+    def _remove_namespace_from_k8s(nsrs, nsr):
+        namespace = "kube-system:"
+        if nsr["_admin"].get("deployed"):
+            k8s_list = []
+            for k8s in nsr["_admin"]["deployed"].get("K8s"):
+                if k8s.get("k8scluster-uuid"):
+                    k8s["k8scluster-uuid"] = k8s["k8scluster-uuid"].replace(namespace, "", 1)
+                k8s_list.append(k8s)
+            myquery = {"_id": nsr["_id"]}
+            nsrs.update_one(myquery, {"$set": {"_admin.deployed.K8s": k8s_list}})
+
+    @staticmethod
+    def _update_nsr(osm_db):
+        """Update nsr.
+
+        Add vim_message = None if it does not exist.
+        Remove "namespace:" from k8scluster-uuid.
+        """
+        if "nsrs" not in osm_db.list_collection_names():
+            return
+        logger.info("Entering in MongoUpgrade1012._update_nsr function")
+
+        nsrs = osm_db["nsrs"]
+        for nsr in nsrs.find():
+            logger.debug(f"Updating {nsr['_id']} nsr")
+            for key, values in nsr.items():
+                if isinstance(values, list):
+                    item_list = []
+                    for value in values:
+                        if isinstance(value, dict) and value.get("vim_info"):
+                            index = list(value["vim_info"].keys())[0]
+                            if not value["vim_info"][index].get("vim_message"):
+                                value["vim_info"][index]["vim_message"] = None
+                            item_list.append(value)
+                    myquery = {"_id": nsr["_id"]}
+                    nsrs.update_one(myquery, {"$set": {key: item_list}})
+            MongoUpgrade1012._remove_namespace_from_k8s(nsrs, nsr)
+
+    @staticmethod
+    def _update_vnfr(osm_db):
+        """Update vnfr.
+
+        Add vim_message to vdur if it does not exist.
+        Copy content of interfaces into interfaces_backup.
+        """
+        if "vnfrs" not in osm_db.list_collection_names():
+            return
+        logger.info("Entering in MongoUpgrade1012._update_vnfr function")
+        mycol = osm_db["vnfrs"]
+        for vnfr in mycol.find():
+            logger.debug(f"Updating {vnfr['_id']} vnfr")
+            vdur_list = []
+            for vdur in vnfr["vdur"]:
+                if vdur.get("vim_info"):
+                    index = list(vdur["vim_info"].keys())[0]
+                    if not vdur["vim_info"][index].get("vim_message"):
+                        vdur["vim_info"][index]["vim_message"] = None
+                    if vdur["vim_info"][index].get(
+                        "interfaces", "Not found"
+                    ) != "Not found" and not vdur["vim_info"][index].get("interfaces_backup"):
+                        vdur["vim_info"][index]["interfaces_backup"] = vdur["vim_info"][index][
+                            "interfaces"
+                        ]
+                vdur_list.append(vdur)
+            myquery = {"_id": vnfr["_id"]}
+            mycol.update_one(myquery, {"$set": {"vdur": vdur_list}})
+
+    @staticmethod
+    def _update_k8scluster(osm_db):
+        """Remove namespace from helm-chart and helm-chart-v3 id."""
+        if "k8sclusters" not in osm_db.list_collection_names():
+            return
+        logger.info("Entering in MongoUpgrade1012._update_k8scluster function")
+        namespace = "kube-system:"
+        k8sclusters = osm_db["k8sclusters"]
+        for k8scluster in k8sclusters.find():
+            if k8scluster["_admin"].get("helm-chart") and k8scluster["_admin"]["helm-chart"].get(
+                "id"
+            ):
+                if k8scluster["_admin"]["helm-chart"]["id"].startswith(namespace):
+                    k8scluster["_admin"]["helm-chart"]["id"] = k8scluster["_admin"]["helm-chart"][
+                        "id"
+                    ].replace(namespace, "", 1)
+            if k8scluster["_admin"].get("helm-chart-v3") and k8scluster["_admin"][
+                "helm-chart-v3"
+            ].get("id"):
+                if k8scluster["_admin"]["helm-chart-v3"]["id"].startswith(namespace):
+                    k8scluster["_admin"]["helm-chart-v3"]["id"] = k8scluster["_admin"][
+                        "helm-chart-v3"
+                    ]["id"].replace(namespace, "", 1)
+            myquery = {"_id": k8scluster["_id"]}
+            k8sclusters.update_one(myquery, {"$set": k8scluster})
+
+    @staticmethod
+    def upgrade(mongo_uri):
+        """Upgrade nsr, vnfr and k8scluster in DB."""
+        logger.info("Entering in MongoUpgrade1012.upgrade function")
+        myclient = MongoClient(mongo_uri)
+        osm_db = myclient["osm"]
+        MongoUpgrade1012._update_nsr(osm_db)
+        MongoUpgrade1012._update_vnfr(osm_db)
+        MongoUpgrade1012._update_k8scluster(osm_db)
+
+
+class MongoUpgrade910:
+    """Upgrade MongoDB Database from OSM v9 to v10."""
+
+    @staticmethod
+    def upgrade(mongo_uri):
+        """Add parameter alarm status = OK if not found in alarms collection."""
+        myclient = MongoClient(mongo_uri)
+        osm_db = myclient["osm"]
+        collist = osm_db.list_collection_names()
+
+        if "alarms" in collist:
+            mycol = osm_db["alarms"]
+            for x in mycol.find():
+                if not x.get("alarm_status"):
+                    myquery = {"_id": x["_id"]}
+                    mycol.update_one(myquery, {"$set": {"alarm_status": "ok"}})
+
+
+class MongoPatch1837:
+    """Patch Bug 1837 on MongoDB."""
+
+    @staticmethod
+    def _update_nslcmops_params(osm_db):
+        """Updates the nslcmops collection to change the additional params to a string."""
+        logger.info("Entering in MongoPatch1837._update_nslcmops_params function")
+        if "nslcmops" in osm_db.list_collection_names():
+            nslcmops = osm_db["nslcmops"]
+            for nslcmop in nslcmops.find():
+                if nslcmop.get("operationParams"):
+                    if nslcmop["operationParams"].get("additionalParamsForVnf") and isinstance(
+                        nslcmop["operationParams"].get("additionalParamsForVnf"), list
+                    ):
+                        string_param = json.dumps(
+                            nslcmop["operationParams"]["additionalParamsForVnf"]
+                        )
+                        myquery = {"_id": nslcmop["_id"]}
+                        nslcmops.update_one(
+                            myquery,
+                            {
+                                "$set": {
+                                    "operationParams": {"additionalParamsForVnf": string_param}
+                                }
+                            },
+                        )
+                    elif nslcmop["operationParams"].get("primitive_params") and isinstance(
+                        nslcmop["operationParams"].get("primitive_params"), dict
+                    ):
+                        string_param = json.dumps(nslcmop["operationParams"]["primitive_params"])
+                        myquery = {"_id": nslcmop["_id"]}
+                        nslcmops.update_one(
+                            myquery,
+                            {"$set": {"operationParams": {"primitive_params": string_param}}},
+                        )
+
+    @staticmethod
+    def _update_vnfrs_params(osm_db):
+        """Updates the vnfrs collection to change the additional params to a string."""
+        logger.info("Entering in MongoPatch1837._update_vnfrs_params function")
+        if "vnfrs" in osm_db.list_collection_names():
+            mycol = osm_db["vnfrs"]
+            for vnfr in mycol.find():
+                if vnfr.get("kdur"):
+                    kdur_list = []
+                    for kdur in vnfr["kdur"]:
+                        if kdur.get("additionalParams") and not isinstance(
+                            kdur["additionalParams"], str
+                        ):
+                            kdur["additionalParams"] = json.dumps(kdur["additionalParams"])
+                        kdur_list.append(kdur)
+                    myquery = {"_id": vnfr["_id"]}
+                    mycol.update_one(
+                        myquery,
+                        {"$set": {"kdur": kdur_list}},
+                    )
+                    vnfr["kdur"] = kdur_list
+
+    @staticmethod
+    def patch(mongo_uri):
+        """Updates the database to change the additional params from dict to a string."""
+        logger.info("Entering in MongoPatch1837.patch function")
+        myclient = MongoClient(mongo_uri)
+        osm_db = myclient["osm"]
+        MongoPatch1837._update_nslcmops_params(osm_db)
+        MongoPatch1837._update_vnfrs_params(osm_db)
+
+
+MONGODB_UPGRADE_FUNCTIONS = {
+    "9": {"10": [MongoUpgrade910.upgrade]},
+    "10": {"12": [MongoUpgrade1012.upgrade]},
+}
+MYSQL_UPGRADE_FUNCTIONS = {}
+BUG_FIXES = {
+    1837: MongoPatch1837.patch,
+}
+
+
+class MongoUpgrade:
+    """Upgrade MongoDB Database."""
+
+    def __init__(self, mongo_uri):
+        self.mongo_uri = mongo_uri
+
+    def upgrade(self, current, target):
+        """Validates the upgrading path and upgrades the DB."""
+        self._validate_upgrade(current, target)
+        for function in MONGODB_UPGRADE_FUNCTIONS.get(current)[target]:
+            function(self.mongo_uri)
+
+    def _validate_upgrade(self, current, target):
+        """Check if the upgrade path chosen is possible."""
+        logger.info("Validating the upgrade path")
+        if current not in MONGODB_UPGRADE_FUNCTIONS:
+            raise Exception(f"cannot upgrade from {current} version.")
+        if target not in MONGODB_UPGRADE_FUNCTIONS[current]:
+            raise Exception(f"cannot upgrade from version {current} to {target}.")
+
+    def apply_patch(self, bug_number: int) -> None:
+        """Checks the bug-number and applies the fix in the database."""
+        if bug_number not in BUG_FIXES:
+            raise Exception(f"There is no patch for bug {bug_number}")
+        patch_function = BUG_FIXES[bug_number]
+        patch_function(self.mongo_uri)
+
+
+class MysqlUpgrade:
+    """Upgrade Mysql Database."""
+
+    def __init__(self, mysql_uri):
+        self.mysql_uri = mysql_uri
+
+    def upgrade(self, current, target):
+        """Validates the upgrading path and upgrades the DB."""
+        self._validate_upgrade(current, target)
+        for function in MYSQL_UPGRADE_FUNCTIONS[current][target]:
+            function(self.mysql_uri)
+
+    def _validate_upgrade(self, current, target):
+        """Check if the upgrade path chosen is possible."""
+        logger.info("Validating the upgrade path")
+        if current not in MYSQL_UPGRADE_FUNCTIONS:
+            raise Exception(f"cannot upgrade from {current} version.")
+        if target not in MYSQL_UPGRADE_FUNCTIONS[current]:
+            raise Exception(f"cannot upgrade from version {current} to {target}.")
diff --git a/installers/charm/osm-update-db-operator/tests/integration/test_charm.py b/installers/charm/osm-update-db-operator/tests/integration/test_charm.py
new file mode 100644
index 0000000..cc9e0be
--- /dev/null
+++ b/installers/charm/osm-update-db-operator/tests/integration/test_charm.py
@@ -0,0 +1,48 @@
+# Copyright 2022 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.
+
+import base64
+import logging
+from pathlib import Path
+
+import pytest
+import yaml
+from pytest_operator.plugin import OpsTest
+
+logger = logging.getLogger(__name__)
+
+METADATA = yaml.safe_load(Path("./metadata.yaml").read_text())
+
+
+@pytest.mark.abort_on_fail
+async def test_build_and_deploy(ops_test: OpsTest):
+    """Build the charm-under-test and deploy it together with related charms.
+
+    Assert on the unit status before any relations/configurations take place.
+    """
+    await ops_test.model.set_config({"update-status-hook-interval": "10s"})
+    # build and deploy charm from local source folder
+    charm = await ops_test.build_charm(".")
+    resources = {
+        "update-db-image": METADATA["resources"]["update-db-image"]["upstream-source"],
+    }
+    await ops_test.model.deploy(charm, resources=resources, application_name="update-db")
+    await ops_test.model.wait_for_idle(apps=["update-db"], status="active", timeout=1000)
+    assert ops_test.model.applications["update-db"].units[0].workload_status == "active"
+
+    await ops_test.model.set_config({"update-status-hook-interval": "60m"})
+
+
+def base64_encode(phrase: str) -> str:
+    return base64.b64encode(phrase.encode("utf-8")).decode("utf-8")
diff --git a/installers/charm/osm-update-db-operator/tests/unit/test_charm.py b/installers/charm/osm-update-db-operator/tests/unit/test_charm.py
new file mode 100644
index 0000000..a0f625d
--- /dev/null
+++ b/installers/charm/osm-update-db-operator/tests/unit/test_charm.py
@@ -0,0 +1,165 @@
+# Copyright 2022 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.
+
+import unittest
+from unittest.mock import Mock, patch
+
+from ops.model import ActiveStatus, BlockedStatus, MaintenanceStatus
+from ops.testing import Harness
+
+from charm import UpgradeDBCharm
+
+
+class TestCharm(unittest.TestCase):
+    def setUp(self):
+        self.harness = Harness(UpgradeDBCharm)
+        self.addCleanup(self.harness.cleanup)
+        self.harness.begin()
+
+    def test_initial_config(self):
+        self.assertEqual(self.harness.model.unit.status, MaintenanceStatus(""))
+
+    def test_config_changed(self):
+        self.harness.update_config({"mongodb-uri": "foo"})
+        self.assertEqual(self.harness.model.unit.status, ActiveStatus())
+
+    def test_config_changed_blocked(self):
+        self.harness.update_config({"log-level": "DEBUG"})
+        self.assertEqual(
+            self.harness.model.unit.status,
+            BlockedStatus("mongodb-uri and/or mysql-uri must be set"),
+        )
+
+    def test_update_db_fail_only_params(self):
+        action_event = Mock(
+            params={
+                "current-version": 9,
+                "target-version": 10,
+                "mysql-only": True,
+                "mongodb-only": True,
+            }
+        )
+        self.harness.charm._on_update_db_action(action_event)
+        self.assertEqual(
+            action_event.fail.call_args,
+            [("Failed DB Upgrade: cannot set both mysql-only and mongodb-only options to True",)],
+        )
+
+    @patch("charm.MongoUpgrade")
+    @patch("charm.MysqlUpgrade")
+    def test_update_db_mysql(self, mock_mysql_upgrade, mock_mongo_upgrade):
+        self.harness.update_config({"mysql-uri": "foo"})
+        action_event = Mock(
+            params={
+                "current-version": 9,
+                "target-version": 10,
+                "mysql-only": True,
+                "mongodb-only": False,
+            }
+        )
+        self.harness.charm._on_update_db_action(action_event)
+        mock_mysql_upgrade().upgrade.assert_called_once()
+        mock_mongo_upgrade.assert_not_called()
+
+    @patch("charm.MongoUpgrade")
+    @patch("charm.MysqlUpgrade")
+    def test_update_db_mongo(self, mock_mysql_upgrade, mock_mongo_upgrade):
+        self.harness.update_config({"mongodb-uri": "foo"})
+        action_event = Mock(
+            params={
+                "current-version": 7,
+                "target-version": 10,
+                "mysql-only": False,
+                "mongodb-only": True,
+            }
+        )
+        self.harness.charm._on_update_db_action(action_event)
+        mock_mongo_upgrade().upgrade.assert_called_once()
+        mock_mysql_upgrade.assert_not_called()
+
+    @patch("charm.MongoUpgrade")
+    def test_update_db_not_configured_mongo_fail(self, mock_mongo_upgrade):
+        action_event = Mock(
+            params={
+                "current-version": 7,
+                "target-version": 10,
+                "mysql-only": False,
+                "mongodb-only": True,
+            }
+        )
+        self.harness.charm._on_update_db_action(action_event)
+        mock_mongo_upgrade.assert_not_called()
+        self.assertEqual(
+            action_event.fail.call_args,
+            [("Failed DB Upgrade: mongo-uri not set",)],
+        )
+
+    @patch("charm.MysqlUpgrade")
+    def test_update_db_not_configured_mysql_fail(self, mock_mysql_upgrade):
+        action_event = Mock(
+            params={
+                "current-version": 7,
+                "target-version": 10,
+                "mysql-only": True,
+                "mongodb-only": False,
+            }
+        )
+        self.harness.charm._on_update_db_action(action_event)
+        mock_mysql_upgrade.assert_not_called()
+        self.assertEqual(
+            action_event.fail.call_args,
+            [("Failed DB Upgrade: mysql-uri not set",)],
+        )
+
+    @patch("charm.MongoUpgrade")
+    @patch("charm.MysqlUpgrade")
+    def test_update_db_mongodb_and_mysql(self, mock_mysql_upgrade, mock_mongo_upgrade):
+        self.harness.update_config({"mongodb-uri": "foo"})
+        self.harness.update_config({"mysql-uri": "foo"})
+        action_event = Mock(
+            params={
+                "current-version": 7,
+                "target-version": 10,
+                "mysql-only": False,
+                "mongodb-only": False,
+            }
+        )
+        self.harness.charm._on_update_db_action(action_event)
+        mock_mysql_upgrade().upgrade.assert_called_once()
+        mock_mongo_upgrade().upgrade.assert_called_once()
+
+    @patch("charm.MongoUpgrade")
+    def test_apply_patch(self, mock_mongo_upgrade):
+        self.harness.update_config({"mongodb-uri": "foo"})
+        action_event = Mock(
+            params={
+                "bug-number": 57,
+            }
+        )
+        self.harness.charm._on_apply_patch_action(action_event)
+        mock_mongo_upgrade().apply_patch.assert_called_once()
+
+    @patch("charm.MongoUpgrade")
+    def test_apply_patch_fail(self, mock_mongo_upgrade):
+        action_event = Mock(
+            params={
+                "bug-number": 57,
+            }
+        )
+        self.harness.charm._on_apply_patch_action(action_event)
+        mock_mongo_upgrade.assert_not_called()
+        self.assertEqual(
+            action_event.fail.call_args,
+            [("Failed Patch Application: mongo-uri not set",)],
+        )
diff --git a/installers/charm/osm-update-db-operator/tests/unit/test_db_upgrade.py b/installers/charm/osm-update-db-operator/tests/unit/test_db_upgrade.py
new file mode 100644
index 0000000..50affdd
--- /dev/null
+++ b/installers/charm/osm-update-db-operator/tests/unit/test_db_upgrade.py
@@ -0,0 +1,413 @@
+# Copyright 2022 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.
+
+import logging
+import unittest
+from unittest.mock import MagicMock, Mock, call, patch
+
+import db_upgrade
+from db_upgrade import (
+    MongoPatch1837,
+    MongoUpgrade,
+    MongoUpgrade910,
+    MongoUpgrade1012,
+    MysqlUpgrade,
+)
+
+logger = logging.getLogger(__name__)
+
+
+class TestUpgradeMongo910(unittest.TestCase):
+    @patch("db_upgrade.MongoClient")
+    def test_upgrade_mongo_9_10(self, mock_mongo_client):
+        mock_db = MagicMock()
+        alarms = Mock()
+        alarms.find.return_value = [{"_id": "1", "alarm_status": "1"}]
+        collection_dict = {"alarms": alarms, "other": {}}
+        mock_db.list_collection_names.return_value = collection_dict
+        mock_db.__getitem__.side_effect = collection_dict.__getitem__
+        mock_mongo_client.return_value = {"osm": mock_db}
+        MongoUpgrade910.upgrade("mongo_uri")
+        alarms.update_one.assert_not_called()
+
+    @patch("db_upgrade.MongoClient")
+    def test_upgrade_mongo_9_10_no_alarms(self, mock_mongo_client):
+        mock_db = Mock()
+        mock_db.__getitem__ = Mock()
+
+        mock_db.list_collection_names.return_value = {"other": {}}
+        mock_db.alarms.return_value = None
+        mock_mongo_client.return_value = {"osm": mock_db}
+        self.assertIsNone(MongoUpgrade910.upgrade("mongo_uri"))
+
+    @patch("db_upgrade.MongoClient")
+    def test_upgrade_mongo_9_10_no_alarm_status(self, mock_mongo_client):
+        mock_db = MagicMock()
+        alarms = Mock()
+        alarms.find.return_value = [{"_id": "1"}]
+        collection_dict = {"alarms": alarms, "other": {}}
+        mock_db.list_collection_names.return_value = collection_dict
+        mock_db.__getitem__.side_effect = collection_dict.__getitem__
+        mock_db.alarms.return_value = alarms
+        mock_mongo_client.return_value = {"osm": mock_db}
+        MongoUpgrade910.upgrade("mongo_uri")
+        alarms.update_one.assert_called_once_with({"_id": "1"}, {"$set": {"alarm_status": "ok"}})
+
+
+class TestUpgradeMongo1012(unittest.TestCase):
+    def setUp(self):
+        self.mock_db = MagicMock()
+        self.nsrs = Mock()
+        self.vnfrs = Mock()
+        self.k8s_clusters = Mock()
+
+    @patch("db_upgrade.MongoClient")
+    def test_update_nsr_empty_nsrs(self, mock_mongo_client):
+        self.nsrs.find.return_value = []
+        collection_list = {"nsrs": self.nsrs}
+        self.mock_db.__getitem__.side_effect = collection_list.__getitem__
+        self.mock_db.list_collection_names.return_value = collection_list
+        mock_mongo_client.return_value = {"osm": self.mock_db}
+        MongoUpgrade1012.upgrade("mongo_uri")
+
+    @patch("db_upgrade.MongoClient")
+    def test_update_nsr_empty_nsr(self, mock_mongo_client):
+        nsr = MagicMock()
+        nsr_values = {"_id": "2", "_admin": {}}
+        nsr.__getitem__.side_effect = nsr_values.__getitem__
+        nsr.items.return_value = []
+        self.nsrs.find.return_value = [nsr]
+        collection_list = {"nsrs": self.nsrs}
+        self.mock_db.__getitem__.side_effect = collection_list.__getitem__
+        self.mock_db.list_collection_names.return_value = collection_list
+        mock_mongo_client.return_value = {"osm": self.mock_db}
+        MongoUpgrade1012.upgrade("mongo_uri")
+
+    @patch("db_upgrade.MongoClient")
+    def test_update_nsr_add_vim_message(self, mock_mongo_client):
+        nsr = MagicMock()
+        vim_info1 = {"vim_info_key1": {}}
+        vim_info2 = {"vim_info_key2": {"vim_message": "Hello"}}
+        nsr_items = {"nsr_item_key": [{"vim_info": vim_info1}, {"vim_info": vim_info2}]}
+        nsr_values = {"_id": "2", "_admin": {}}
+        nsr.__getitem__.side_effect = nsr_values.__getitem__
+        nsr.items.return_value = nsr_items.items()
+        self.nsrs.find.return_value = [nsr]
+        collection_list = {"nsrs": self.nsrs}
+        self.mock_db.__getitem__.side_effect = collection_list.__getitem__
+        self.mock_db.list_collection_names.return_value = collection_list
+        mock_mongo_client.return_value = {"osm": self.mock_db}
+        MongoUpgrade1012.upgrade("mongo_uri")
+        expected_vim_info = {"vim_info_key1": {"vim_message": None}}
+        expected_vim_info2 = {"vim_info_key2": {"vim_message": "Hello"}}
+        self.assertEqual(vim_info1, expected_vim_info)
+        self.assertEqual(vim_info2, expected_vim_info2)
+        self.nsrs.update_one.assert_called_once_with({"_id": "2"}, {"$set": nsr_items})
+
+    @patch("db_upgrade.MongoClient")
+    def test_update_nsr_admin(self, mock_mongo_client):
+        nsr = MagicMock()
+        k8s = [{"k8scluster-uuid": "namespace"}, {"k8scluster-uuid": "kube-system:k8s"}]
+        admin = {"deployed": {"K8s": k8s}}
+        nsr_values = {"_id": "2", "_admin": admin}
+        nsr.__getitem__.side_effect = nsr_values.__getitem__
+        nsr_items = {}
+        nsr.items.return_value = nsr_items.items()
+        self.nsrs.find.return_value = [nsr]
+        collection_list = {"nsrs": self.nsrs}
+        self.mock_db.__getitem__.side_effect = collection_list.__getitem__
+        self.mock_db.list_collection_names.return_value = collection_list
+        mock_mongo_client.return_value = {"osm": self.mock_db}
+        MongoUpgrade1012.upgrade("mongo_uri")
+        expected_k8s = [{"k8scluster-uuid": "namespace"}, {"k8scluster-uuid": "k8s"}]
+        self.nsrs.update_one.assert_called_once_with(
+            {"_id": "2"}, {"$set": {"_admin.deployed.K8s": expected_k8s}}
+        )
+
+    @patch("db_upgrade.MongoClient")
+    def test_update_vnfr_empty_vnfrs(self, mock_mongo_client):
+        self.vnfrs.find.return_value = [{"_id": "10", "vdur": []}]
+        collection_list = {"vnfrs": self.vnfrs}
+        self.mock_db.__getitem__.side_effect = collection_list.__getitem__
+        self.mock_db.list_collection_names.return_value = collection_list
+        mock_mongo_client.return_value = {"osm": self.mock_db}
+        MongoUpgrade1012.upgrade("mongo_uri")
+        self.vnfrs.update_one.assert_called_once_with({"_id": "10"}, {"$set": {"vdur": []}})
+
+    @patch("db_upgrade.MongoClient")
+    def test_update_vnfr_no_vim_info(self, mock_mongo_client):
+        vdur = {"other": {}}
+        vnfr = {"_id": "10", "vdur": [vdur]}
+        self.vnfrs.find.return_value = [vnfr]
+        collection_list = {"vnfrs": self.vnfrs}
+        self.mock_db.__getitem__.side_effect = collection_list.__getitem__
+        self.mock_db.list_collection_names.return_value = collection_list
+        mock_mongo_client.return_value = {"osm": self.mock_db}
+        MongoUpgrade1012.upgrade("mongo_uri")
+        self.assertEqual(vdur, {"other": {}})
+        self.vnfrs.update_one.assert_called_once_with({"_id": "10"}, {"$set": {"vdur": [vdur]}})
+
+    @patch("db_upgrade.MongoClient")
+    def test_update_vnfr_vim_message_not_conditions_matched(self, mock_mongo_client):
+        vim_info = {"vim_message": "HelloWorld"}
+        vim_infos = {"key1": vim_info, "key2": "value2"}
+        vdur = {"vim_info": vim_infos, "other": {}}
+        vnfr = {"_id": "10", "vdur": [vdur]}
+        self.vnfrs.find.return_value = [vnfr]
+        collection_list = {"vnfrs": self.vnfrs}
+        self.mock_db.__getitem__.side_effect = collection_list.__getitem__
+        self.mock_db.list_collection_names.return_value = collection_list
+        mock_mongo_client.return_value = {"osm": self.mock_db}
+        MongoUpgrade1012.upgrade("mongo_uri")
+        expected_vim_info = {"vim_message": "HelloWorld"}
+        self.assertEqual(vim_info, expected_vim_info)
+        self.vnfrs.update_one.assert_called_once_with({"_id": "10"}, {"$set": {"vdur": [vdur]}})
+
+    @patch("db_upgrade.MongoClient")
+    def test_update_vnfr_vim_message_is_missing(self, mock_mongo_client):
+        vim_info = {"interfaces_backup": "HelloWorld"}
+        vim_infos = {"key1": vim_info, "key2": "value2"}
+        vdur = {"vim_info": vim_infos, "other": {}}
+        vnfr = {"_id": "10", "vdur": [vdur]}
+        self.vnfrs.find.return_value = [vnfr]
+        collection_list = {"vnfrs": self.vnfrs}
+        self.mock_db.__getitem__.side_effect = collection_list.__getitem__
+        self.mock_db.list_collection_names.return_value = collection_list
+        mock_mongo_client.return_value = {"osm": self.mock_db}
+        MongoUpgrade1012.upgrade("mongo_uri")
+        expected_vim_info = {"vim_message": None, "interfaces_backup": "HelloWorld"}
+        self.assertEqual(vim_info, expected_vim_info)
+        self.vnfrs.update_one.assert_called_once_with({"_id": "10"}, {"$set": {"vdur": [vdur]}})
+
+    @patch("db_upgrade.MongoClient")
+    def test_update_vnfr_interfaces_backup_is_updated(self, mock_mongo_client):
+        vim_info = {"interfaces": "HelloWorld", "vim_message": "ByeWorld"}
+        vim_infos = {"key1": vim_info, "key2": "value2"}
+        vdur = {"vim_info": vim_infos, "other": {}}
+        vnfr = {"_id": "10", "vdur": [vdur]}
+        self.vnfrs.find.return_value = [vnfr]
+        collection_list = {"vnfrs": self.vnfrs}
+        self.mock_db.__getitem__.side_effect = collection_list.__getitem__
+        self.mock_db.list_collection_names.return_value = collection_list
+        mock_mongo_client.return_value = {"osm": self.mock_db}
+        MongoUpgrade1012.upgrade("mongo_uri")
+        expected_vim_info = {
+            "interfaces": "HelloWorld",
+            "vim_message": "ByeWorld",
+            "interfaces_backup": "HelloWorld",
+        }
+        self.assertEqual(vim_info, expected_vim_info)
+        self.vnfrs.update_one.assert_called_once_with({"_id": "10"}, {"$set": {"vdur": [vdur]}})
+
+    @patch("db_upgrade.MongoClient")
+    def test_update_k8scluster_empty_k8scluster(self, mock_mongo_client):
+        self.k8s_clusters.find.return_value = []
+        collection_list = {"k8sclusters": self.k8s_clusters}
+        self.mock_db.__getitem__.side_effect = collection_list.__getitem__
+        self.mock_db.list_collection_names.return_value = collection_list
+        mock_mongo_client.return_value = {"osm": self.mock_db}
+        MongoUpgrade1012.upgrade("mongo_uri")
+
+    @patch("db_upgrade.MongoClient")
+    def test_update_k8scluster_replace_namespace_in_helm_chart(self, mock_mongo_client):
+        helm_chart = {"id": "kube-system:Hello", "other": {}}
+        k8s_cluster = {"_id": "8", "_admin": {"helm-chart": helm_chart}}
+        self.k8s_clusters.find.return_value = [k8s_cluster]
+        collection_list = {"k8sclusters": self.k8s_clusters}
+        self.mock_db.__getitem__.side_effect = collection_list.__getitem__
+        self.mock_db.list_collection_names.return_value = collection_list
+        mock_mongo_client.return_value = {"osm": self.mock_db}
+        MongoUpgrade1012.upgrade("mongo_uri")
+        expected_helm_chart = {"id": "Hello", "other": {}}
+        expected_k8s_cluster = {"_id": "8", "_admin": {"helm-chart": expected_helm_chart}}
+        self.k8s_clusters.update_one.assert_called_once_with(
+            {"_id": "8"}, {"$set": expected_k8s_cluster}
+        )
+
+    @patch("db_upgrade.MongoClient")
+    def test_update_k8scluster_replace_namespace_in_helm_chart_v3(self, mock_mongo_client):
+        helm_chart_v3 = {"id": "kube-system:Hello", "other": {}}
+        k8s_cluster = {"_id": "8", "_admin": {"helm-chart-v3": helm_chart_v3}}
+        self.k8s_clusters.find.return_value = [k8s_cluster]
+        collection_list = {"k8sclusters": self.k8s_clusters}
+        self.mock_db.__getitem__.side_effect = collection_list.__getitem__
+        self.mock_db.list_collection_names.return_value = collection_list
+        mock_mongo_client.return_value = {"osm": self.mock_db}
+        MongoUpgrade1012.upgrade("mongo_uri")
+        expected_helm_chart_v3 = {"id": "Hello", "other": {}}
+        expected_k8s_cluster = {"_id": "8", "_admin": {"helm-chart-v3": expected_helm_chart_v3}}
+        self.k8s_clusters.update_one.assert_called_once_with(
+            {"_id": "8"}, {"$set": expected_k8s_cluster}
+        )
+
+
+class TestPatch1837(unittest.TestCase):
+    def setUp(self):
+        self.mock_db = MagicMock()
+        self.vnfrs = Mock()
+        self.nslcmops = Mock()
+
+    @patch("db_upgrade.MongoClient")
+    def test_update_vnfrs_params_no_vnfrs_or_nslcmops(self, mock_mongo_client):
+        collection_dict = {"other": {}}
+        self.mock_db.list_collection_names.return_value = collection_dict
+        mock_mongo_client.return_value = {"osm": self.mock_db}
+        MongoPatch1837.patch("mongo_uri")
+
+    @patch("db_upgrade.MongoClient")
+    def test_update_vnfrs_params_no_kdur(self, mock_mongo_client):
+        self.vnfrs.find.return_value = {"_id": "1"}
+        collection_dict = {"vnfrs": self.vnfrs, "other": {}}
+        self.mock_db.list_collection_names.return_value = collection_dict
+        mock_mongo_client.return_value = {"osm": self.mock_db}
+        MongoPatch1837.patch("mongo_uri")
+
+    @patch("db_upgrade.MongoClient")
+    def test_update_vnfrs_params_kdur_without_additional_params(self, mock_mongo_client):
+        kdur = [{"other": {}}]
+        self.vnfrs.find.return_value = [{"_id": "1", "kdur": kdur}]
+        collection_dict = {"vnfrs": self.vnfrs, "other": {}}
+        self.mock_db.list_collection_names.return_value = collection_dict
+        self.mock_db.__getitem__.side_effect = collection_dict.__getitem__
+        mock_mongo_client.return_value = {"osm": self.mock_db}
+        MongoPatch1837.patch("mongo_uri")
+        self.vnfrs.update_one.assert_called_once_with({"_id": "1"}, {"$set": {"kdur": kdur}})
+
+    @patch("db_upgrade.MongoClient")
+    def test_update_vnfrs_params_kdur_two_additional_params(self, mock_mongo_client):
+        kdur1 = {"additionalParams": "additional_params", "other": {}}
+        kdur2 = {"additionalParams": 4, "other": {}}
+        kdur = [kdur1, kdur2]
+        self.vnfrs.find.return_value = [{"_id": "1", "kdur": kdur}]
+        collection_dict = {"vnfrs": self.vnfrs, "other": {}}
+        self.mock_db.list_collection_names.return_value = collection_dict
+        self.mock_db.__getitem__.side_effect = collection_dict.__getitem__
+        mock_mongo_client.return_value = {"osm": self.mock_db}
+        MongoPatch1837.patch("mongo_uri")
+        self.vnfrs.update_one.assert_called_once_with(
+            {"_id": "1"}, {"$set": {"kdur": [kdur1, {"additionalParams": "4", "other": {}}]}}
+        )
+
+    @patch("db_upgrade.MongoClient")
+    def test_update_nslcmops_params_no_nslcmops(self, mock_mongo_client):
+        self.nslcmops.find.return_value = []
+        collection_dict = {"nslcmops": self.nslcmops, "other": {}}
+        self.mock_db.list_collection_names.return_value = collection_dict
+        self.mock_db.__getitem__.side_effect = collection_dict.__getitem__
+        mock_mongo_client.return_value = {"osm": self.mock_db}
+        MongoPatch1837.patch("mongo_uri")
+
+    @patch("db_upgrade.MongoClient")
+    def test_update_nslcmops_additional_params(self, mock_mongo_client):
+        operation_params_list = {"additionalParamsForVnf": [1, 2, 3]}
+        operation_params_dict = {"primitive_params": {"dict_key": 5}}
+        nslcmops1 = {"_id": "1", "other": {}}
+        nslcmops2 = {"_id": "2", "operationParams": operation_params_list, "other": {}}
+        nslcmops3 = {"_id": "3", "operationParams": operation_params_dict, "other": {}}
+        self.nslcmops.find.return_value = [nslcmops1, nslcmops2, nslcmops3]
+        collection_dict = {"nslcmops": self.nslcmops, "other": {}}
+        self.mock_db.list_collection_names.return_value = collection_dict
+        self.mock_db.__getitem__.side_effect = collection_dict.__getitem__
+        mock_mongo_client.return_value = {"osm": self.mock_db}
+        MongoPatch1837.patch("mongo_uri")
+        call1 = call(
+            {"_id": "2"}, {"$set": {"operationParams": {"additionalParamsForVnf": "[1, 2, 3]"}}}
+        )
+        call2 = call(
+            {"_id": "3"}, {"$set": {"operationParams": {"primitive_params": '{"dict_key": 5}'}}}
+        )
+        expected_calls = [call1, call2]
+        self.nslcmops.update_one.assert_has_calls(expected_calls)
+
+
+class TestMongoUpgrade(unittest.TestCase):
+    def setUp(self):
+        self.mongo = MongoUpgrade("http://fake_mongo:27017")
+        self.upgrade_function = Mock()
+        self.patch_function = Mock()
+        db_upgrade.MONGODB_UPGRADE_FUNCTIONS = {"9": {"10": [self.upgrade_function]}}
+        db_upgrade.BUG_FIXES = {1837: self.patch_function}
+
+    def test_validate_upgrade_fail_target(self):
+        valid_current = "9"
+        invalid_target = "7"
+        with self.assertRaises(Exception) as context:
+            self.mongo._validate_upgrade(valid_current, invalid_target)
+        self.assertEqual("cannot upgrade from version 9 to 7.", str(context.exception))
+
+    def test_validate_upgrade_fail_current(self):
+        invalid_current = "7"
+        invalid_target = "8"
+        with self.assertRaises(Exception) as context:
+            self.mongo._validate_upgrade(invalid_current, invalid_target)
+        self.assertEqual("cannot upgrade from 7 version.", str(context.exception))
+
+    def test_validate_upgrade_pass(self):
+        valid_current = "9"
+        valid_target = "10"
+        self.assertIsNone(self.mongo._validate_upgrade(valid_current, valid_target))
+
+    @patch("db_upgrade.MongoUpgrade._validate_upgrade")
+    def test_update_mongo_success(self, mock_validate):
+        valid_current = "9"
+        valid_target = "10"
+        mock_validate.return_value = ""
+        self.mongo.upgrade(valid_current, valid_target)
+        self.upgrade_function.assert_called_once()
+
+    def test_validate_apply_patch(self):
+        bug_number = 1837
+        self.mongo.apply_patch(bug_number)
+        self.patch_function.assert_called_once()
+
+    def test_validate_apply_patch_invalid_bug_fail(self):
+        bug_number = 2
+        with self.assertRaises(Exception) as context:
+            self.mongo.apply_patch(bug_number)
+        self.assertEqual("There is no patch for bug 2", str(context.exception))
+        self.patch_function.assert_not_called()
+
+
+class TestMysqlUpgrade(unittest.TestCase):
+    def setUp(self):
+        self.mysql = MysqlUpgrade("mysql://fake_mysql:23023")
+        self.upgrade_function = Mock()
+        db_upgrade.MYSQL_UPGRADE_FUNCTIONS = {"9": {"10": [self.upgrade_function]}}
+
+    def test_validate_upgrade_mysql_fail_current(self):
+        invalid_current = "7"
+        invalid_target = "8"
+        with self.assertRaises(Exception) as context:
+            self.mysql._validate_upgrade(invalid_current, invalid_target)
+        self.assertEqual("cannot upgrade from 7 version.", str(context.exception))
+
+    def test_validate_upgrade_mysql_fail_target(self):
+        valid_current = "9"
+        invalid_target = "7"
+        with self.assertRaises(Exception) as context:
+            self.mysql._validate_upgrade(valid_current, invalid_target)
+        self.assertEqual("cannot upgrade from version 9 to 7.", str(context.exception))
+
+    def test_validate_upgrade_mysql_success(self):
+        valid_current = "9"
+        valid_target = "10"
+        self.assertIsNone(self.mysql._validate_upgrade(valid_current, valid_target))
+
+    @patch("db_upgrade.MysqlUpgrade._validate_upgrade")
+    def test_upgrade_mysql_success(self, mock_validate):
+        valid_current = "9"
+        valid_target = "10"
+        mock_validate.return_value = ""
+        self.mysql.upgrade(valid_current, valid_target)
+        self.upgrade_function.assert_called_once()
diff --git a/installers/charm/osm-update-db-operator/tox.ini b/installers/charm/osm-update-db-operator/tox.ini
new file mode 100644
index 0000000..bcf628a
--- /dev/null
+++ b/installers/charm/osm-update-db-operator/tox.ini
@@ -0,0 +1,104 @@
+# Copyright 2022 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.
+
+[tox]
+skipsdist=True
+skip_missing_interpreters = True
+envlist = lint, unit
+
+[vars]
+src_path = {toxinidir}/src/
+tst_path = {toxinidir}/tests/
+;lib_path = {toxinidir}/lib/charms/
+all_path = {[vars]src_path} {[vars]tst_path}
+
+[testenv]
+basepython = python3
+setenv =
+  PYTHONPATH = {toxinidir}:{toxinidir}/lib:{[vars]src_path}
+  PYTHONBREAKPOINT=ipdb.set_trace
+passenv =
+  PYTHONPATH
+  HOME
+  PATH
+  CHARM_BUILD_DIR
+  MODEL_SETTINGS
+  HTTP_PROXY
+  HTTPS_PROXY
+  NO_PROXY
+
+[testenv:fmt]
+description = Apply coding style standards to code
+deps =
+    black
+    isort
+commands =
+    isort {[vars]all_path}
+    black {[vars]all_path}
+
+[testenv:lint]
+description = Check code against coding style standards
+deps =
+    black
+    flake8>= 4.0.0, < 5.0.0
+    flake8-docstrings
+    flake8-copyright
+    flake8-builtins
+    # prospector[with_everything]
+    pylint
+    pyproject-flake8
+    pep8-naming
+    isort
+    codespell
+    yamllint
+    -r{toxinidir}/requirements.txt
+commands =
+    codespell {toxinidir}/*.yaml {toxinidir}/*.ini {toxinidir}/*.md \
+      {toxinidir}/*.toml {toxinidir}/*.txt {toxinidir}/.github
+    # prospector -A -F -T
+    pylint -E {[vars]src_path}
+    yamllint -d '\{extends: default, ignore: "build\n.tox" \}' .
+    # pflake8 wrapper supports config from pyproject.toml
+    pflake8 {[vars]all_path}
+    isort --check-only --diff {[vars]all_path}
+    black --check --diff {[vars]all_path}
+
+[testenv:unit]
+description = Run unit tests
+deps =
+    pytest
+    pytest-mock
+    pytest-cov
+    coverage[toml]
+    -r{toxinidir}/requirements.txt
+commands =
+    pytest --ignore={[vars]tst_path}integration --cov={[vars]src_path} --cov-report=xml
+    coverage report
+
+[testenv:security]
+description = Run security tests
+deps =
+    bandit
+    safety
+commands =
+    bandit -r {[vars]src_path}
+    - safety check
+
+[testenv:integration]
+description = Run integration tests
+deps =
+    pytest
+    pytest-operator
+commands =
+    pytest -v --tb native --ignore={[vars]tst_path}unit --log-cli-level=INFO -s {posargs}