installers/charm/kafka-exporter/src/charm.py

   1 #!/usr/bin/env python3
   2 # Copyright 2021 Canonical Ltd.
   3 #
   4 # Licensed under the Apache License, Version 2.0 (the "License"); you may
   5 # not use this file except in compliance with the License. You may obtain
   6 # a copy of the License at
   7 #
   8 #         http://www.apache.org/licenses/LICENSE-2.0
   9 #
  10 # Unless required by applicable law or agreed to in writing, software
  11 # distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
  12 # WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
  13 # License for the specific language governing permissions and limitations
  14 # under the License.
  15 #
  16 # For those usages not covered by the Apache License, Version 2.0 please
  17 # contact: legal@canonical.com
  18 #
  19 # To get in touch with the maintainers, please contact:
  20 # osm-charmers@lists.launchpad.net
  21 ##
  22
  23 # pylint: disable=E0213
  24
  25 from ipaddress import ip_network
  26 import logging
  27 from pathlib import Path
  28 from typing import NoReturn, Optional
  29 from urllib.parse import urlparse
  30
  31 from ops.main import main
  32 from opslib.osm.charm import CharmedOsmBase, RelationsMissing
  33 from opslib.osm.interfaces.grafana import GrafanaDashboardTarget
  34 from opslib.osm.interfaces.kafka import KafkaClient
  35 from opslib.osm.interfaces.prometheus import PrometheusScrapeTarget
  36 from opslib.osm.pod import (
  37     ContainerV3Builder,
  38     IngressResourceV3Builder,
  39     PodSpecV3Builder,
  40 )
  41 from opslib.osm.validator import ModelValidator, validator
  42
  43
  44 logger = logging.getLogger(__name__)
  45
  46 PORT = 9308
  47
  48
  49 class ConfigModel(ModelValidator):
  50     site_url: Optional[str]
  51     cluster_issuer: Optional[str]
  52     ingress_class: Optional[str]
  53     ingress_whitelist_source_range: Optional[str]
  54     tls_secret_name: Optional[str]
  55     image_pull_policy: str
  56     security_context: bool
  57
  58     @validator("site_url")
  59     def validate_site_url(cls, v):
  60         if v:
  61             parsed = urlparse(v)
  62             if not parsed.scheme.startswith("http"):
  63                 raise ValueError("value must start with http")
  64         return v
  65
  66     @validator("ingress_whitelist_source_range")
  67     def validate_ingress_whitelist_source_range(cls, v):
  68         if v:
  69             ip_network(v)
  70         return v
  71
  72     @validator("image_pull_policy")
  73     def validate_image_pull_policy(cls, v):
  74         values = {
  75             "always": "Always",
  76             "ifnotpresent": "IfNotPresent",
  77             "never": "Never",
  78         }
  79         v = v.lower()
  80         if v not in values.keys():
  81             raise ValueError("value must be always, ifnotpresent or never")
  82         return values[v]
  83
  84
  85 class KafkaExporterCharm(CharmedOsmBase):
  86     def __init__(self, *args) -> NoReturn:
  87         super().__init__(*args, oci_image="image")
  88
  89         # Provision Kafka relation to exchange information
  90         self.kafka_client = KafkaClient(self, "kafka")
  91         self.framework.observe(self.on["kafka"].relation_changed, self.configure_pod)
  92         self.framework.observe(self.on["kafka"].relation_broken, self.configure_pod)
  93
  94         # Register relation to provide a Scraping Target
  95         self.scrape_target = PrometheusScrapeTarget(self, "prometheus-scrape")
  96         self.framework.observe(
  97             self.on["prometheus-scrape"].relation_joined, self._publish_scrape_info
  98         )
  99
 100         # Register relation to provide a Dasboard Target
 101         self.dashboard_target = GrafanaDashboardTarget(self, "grafana-dashboard")
 102         self.framework.observe(
 103             self.on["grafana-dashboard"].relation_joined, self._publish_dashboard_info
 104         )
 105
 106     def _publish_scrape_info(self, event) -> NoReturn:
 107         """Publishes scraping information for Prometheus.
 108
 109         Args:
 110             event (EventBase): Prometheus relation event.
 111         """
 112         if self.unit.is_leader():
 113             hostname = (
 114                 urlparse(self.model.config["site_url"]).hostname
 115                 if self.model.config["site_url"]
 116                 else self.model.app.name
 117             )
 118             port = str(PORT)
 119             if self.model.config.get("site_url", "").startswith("https://"):
 120                 port = "443"
 121             elif self.model.config.get("site_url", "").startswith("http://"):
 122                 port = "80"
 123
 124             self.scrape_target.publish_info(
 125                 hostname=hostname,
 126                 port=port,
 127                 metrics_path="/metrics",
 128                 scrape_interval="30s",
 129                 scrape_timeout="15s",
 130             )
 131
 132     def _publish_dashboard_info(self, event) -> NoReturn:
 133         """Publish dashboards for Grafana.
 134
 135         Args:
 136             event (EventBase): Grafana relation event.
 137         """
 138         if self.unit.is_leader():
 139             self.dashboard_target.publish_info(
 140                 name="osm-kafka",
 141                 dashboard=Path("templates/kafka_exporter_dashboard.json").read_text(),
 142             )
 143
 144     def _check_missing_dependencies(self, config: ConfigModel):
 145         """Check if there is any relation missing.
 146
 147         Args:
 148             config (ConfigModel): object with configuration information.
 149
 150         Raises:
 151             RelationsMissing: if kafka is missing.
 152         """
 153         missing_relations = []
 154
 155         if self.kafka_client.is_missing_data_in_unit():
 156             missing_relations.append("kafka")
 157
 158         if missing_relations:
 159             raise RelationsMissing(missing_relations)
 160
 161     def build_pod_spec(self, image_info):
 162         """Build the PodSpec to be used.
 163
 164         Args:
 165             image_info (str): container image information.
 166
 167         Returns:
 168             Dict: PodSpec information.
 169         """
 170         # Validate config
 171         config = ConfigModel(**dict(self.config))
 172
 173         # Check relations
 174         self._check_missing_dependencies(config)
 175
 176         # Create Builder for the PodSpec
 177         pod_spec_builder = PodSpecV3Builder(
 178             enable_security_context=config.security_context
 179         )
 180
 181         # Build container
 182         container_builder = ContainerV3Builder(
 183             self.app.name,
 184             image_info,
 185             config.image_pull_policy,
 186             run_as_non_root=config.security_context,
 187         )
 188         container_builder.add_port(name=self.app.name, port=PORT)
 189         container_builder.add_http_readiness_probe(
 190             path="/api/health",
 191             port=PORT,
 192             initial_delay_seconds=10,
 193             period_seconds=10,
 194             timeout_seconds=5,
 195             success_threshold=1,
 196             failure_threshold=3,
 197         )
 198         container_builder.add_http_liveness_probe(
 199             path="/api/health",
 200             port=PORT,
 201             initial_delay_seconds=60,
 202             timeout_seconds=30,
 203             failure_threshold=10,
 204         )
 205         container_builder.add_command(
 206             [
 207                 "kafka_exporter",
 208                 f"--kafka.server={self.kafka_client.host}:{self.kafka_client.port}",
 209             ]
 210         )
 211         container = container_builder.build()
 212
 213         # Add container to PodSpec
 214         pod_spec_builder.add_container(container)
 215
 216         # Add ingress resources to PodSpec if site url exists
 217         if config.site_url:
 218             parsed = urlparse(config.site_url)
 219             annotations = {}
 220             if config.ingress_class:
 221                 annotations["kubernetes.io/ingress.class"] = config.ingress_class
 222             ingress_resource_builder = IngressResourceV3Builder(
 223                 f"{self.app.name}-ingress", annotations
 224             )
 225
 226             if config.ingress_whitelist_source_range:
 227                 annotations[
 228                     "nginx.ingress.kubernetes.io/whitelist-source-range"
 229                 ] = config.ingress_whitelist_source_range
 230
 231             if config.cluster_issuer:
 232                 annotations["cert-manager.io/cluster-issuer"] = config.cluster_issuer
 233
 234             if parsed.scheme == "https":
 235                 ingress_resource_builder.add_tls(
 236                     [parsed.hostname], config.tls_secret_name
 237                 )
 238             else:
 239                 annotations["nginx.ingress.kubernetes.io/ssl-redirect"] = "false"
 240
 241             ingress_resource_builder.add_rule(parsed.hostname, self.app.name, PORT)
 242             ingress_resource = ingress_resource_builder.build()
 243             pod_spec_builder.add_ingress_resource(ingress_resource)
 244
 245         return pod_spec_builder.build()
 246
 247
 248 if __name__ == "__main__":
 249     main(KafkaExporterCharm)