Prometheus Charmed Operator for Kubernetes
Description
The Prometheus Charmed Operator for Juju provides a monitoring solution using Prometheus, which is an open-source monitoring system and alerting toolkit. Besides it handles instantiation, scaling, configuration, and Day 2 operations specific to Prometheus.
This Charm is also part of the Canonical Observability Stack and deploys only the monitoring component of Prometheus in a Kubernetes cluster. An alerting service for Prometheus is offered through a separate Charm.
Getting Started
Basic Deployment
Create a Juju model for your operator, say "observability"
juju add-model observability
The Prometheus Charmed Operator may now be deployed using the Juju command line as in
juju deploy prometheus-k8s --channel=stable
Checking deployment status
Progress of the Prometheus charm deployment and its current status may be viewed anytime using the Juju command line.
juju status --color --relations
Once the Prometheus charm deployments completes, you may expect to see a status result such as
$ juju status --relations
Model Controller Cloud/Region Version SLA Timestamp
cos charm-dev-batteries microk8s/localhost 3.0.2 unsupported 14:27:58-03:00
App Version Status Scale Charm Channel Rev Address Exposed Message
prometheus-k8s 2.33.5 active 1 prometheus-k8s stable 79 10.152.183.227 no
Unit Workload Agent Address Ports Message
prometheus-k8s/0* active idle 10.1.36.90
Relation provider Requirer Interface Type Message
prometheus-k8s:prometheus-peers prometheus-k8s:prometheus-peers prometheus_peers peer
Accessing the Prometheus User Interface
Prometheus provides a user interface that let us explore the data that has collected such as metrics and associated alerts.
This UI is accessed on port 9090 at the Prometheus charm's address. This assumes the Prometheus host address is accessible from the host your browser is running on. For example the Juju status message shown above is from a microk8s cluster, hence navigating to http://10.152.183.227:9090 will show us the Prometheus UI.
Adding scrape targets
When Prometheus is deployed it does not scrape any metrics endpoints. Metrics endpoints may be added to the Prometheus charm through relations with other charms. Currently the following charms are supported
- Any charm that uses the
prometheus_scrape interface to provide a metrics endpoint and optionally alert rules for Prometheus.
- The Prometheus Scrape Target charm may be used to scrape metrics endpoint that are not part of any Juju Model.
- The Prometheus Scrape Config charm may be used to scrape metrics endpoints across different Juju models. The charm also support overriding some of the scrape job configurations provided by metrics endpoints.
Relations
At present the Prometheus Charmed Operator for Kubernetes supports eight relations.
Requires
Metrics Endpoint:
metrics-endpoint:
interface: prometheus_scrape
Charms may forward information about their metrics endpoints and associated alert rules to the Prometheus charm over the metrics-endpoint relation using the prometheus_scrape interface. In order for these metrics to be aggregated by this Prometheus charm all that is required is to relate the two charms as in:
juju relate kube-state-metrics-k8s prometheus-k8s
Charms that seek to provide metrics endpoints and alert rules for Prometheus must do so using the provided prometheus_scrape charm library. This library by implementing the metrics-endpoint relation, not only ensures that scrape jobs and alert rules are forward to Prometheus but also that these are updated any time the metrics provider charm is upgraded. For example new alert rules may be added or old ones removed by updating and releasing a new version of the metrics provider charm. While it is safe to update alert rules as desired, care must be taken when updating scrape job specifications as this has the potential to break the continuity of the scraped metrics time series. In particular changing the following keys in the scrape job can break time series continuity
job_namerelabel_configsmetric_relabel_configs- Any label set by
static_configs
Evaluation of alert rules forwarded through the prometheus_scrape interface are automatically limited to the charmed application that provided these rules. This ensures that alert rule evaluation is scoped down to the charm providing the rules.
Alerting
alertmanager:
interface: alertmanager_dispatch
This is the beginning of the README. Read the rest at the original. Read the full README ↗
