Prometheus

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Prometheus is an open-source software application used for event monitoring and alerting. It records real-time metrics in a time series database built using an HTTP pull model, with flexible query language and real-time alerting.

Prometheus parameters and supported features in Nobl9

General support:: Release channel: Stable, Beta; Connection method: Agent; Replay and SLI Analyzer: Historical data limit 30 days; Event logs: Not supported; Query checker: Not supported; Query parameters retrieval: Supported; Timestamp cache persistence: Supported
Query parameters:: Query interval: 1 min; Query delay: 0; Jitter: 15 sec; Timeout: 30 sec
Agent details and minimum required versions for supported features:: Plugin name: n9prometheus; Query delay environment variable: PROM_QUERY_DELAY; Replay and SLI Analyzer: 0.65.0; Query parameters retrieval: 0.73.2; Timestamp cache persistence: 0.65.0; Custom HTTP headers: 0.83.0-beta

Authentication

Prometheus does not provide an authentication layer, the Nobl9 agent only collects the URL for the Prometheus integration definition. Authentication is up to the user. Operators are expected to run an authenticating reverse proxy in front of their services, such as NGINX using basic auth or an OAuth2 proxy.

URL

Prometheus agent makes requests to Range Queries | Prometheus documentation API endpoint in the form /api/v1/query_range. For example:

GET /api/v1/query_range
POST /api/v1/query_range

Hence, do not include the above API path in the URL. Specify only the base URL for the Prometheus server. For example, if your Prometheus server is available under <http://prometheus.example.com> and you access API via <http://prometheus.example.com/api/v1>, use only <http://prometheus.example.com>.

Other APIs or Web UIs have similar path endings, which should also be omitted, for example, the /graph part of the path.

The Prometheus integration does not integrate directly with data exposed from services in the Prometheus Format | Prometheus documentation, usually under /metrics path. Do not set the URL to metrics exposed directly from such a service.

Basic authentication

Since Prometheus does not provide an authentication layer, the authentication method is up to the users. Normally, Loki's users are expected to run an authenticating reverse proxy in front of their services, such as NGINX using basic_auth proxy.

If that's the method you use, the Nobl9 agent version equal to or higher than 0.40.0, allows you to send an additional Authorization request header with the basic_auth. Refer to the section below for more details.

Bearer token authentication

You can also authenticate the Nobl9 Prometheus agent using bearer token. If you choose this method, you need to specify the variables for AUTH_METHOD and BEARER_TOKEN when deploying your Prometheus agent in Docker or Kubernetes. Refer to the section below for more details.

Adding Prometheus as a data source

You can add the Prometheus data source using the agent connection method.

Nobl9 Web

Follow the instructions below to create your Prometheus agent connection:

Navigate to Integrations > Sources.
Click .
Click the required Source button.
Choose Agent.

Select one of the following Release Channels:
- The stable channel is fully tested by the Nobl9 team. It represents the final product; however, this channel does not contain all the new features of a beta release. Use it to avoid crashes and other limitations.
- The beta channel is under active development. Here, you can check out new features and improvements without the risk of affecting any viable SLOs. Remember that features in this channel can change.
Add the URL to connect to your data source (mandatory).
Refer to the Authentication section for more details.

Select a Project.
Specifying a project is helpful when multiple users are spread across multiple teams or projects. When the Project field is left blank, Nobl9 uses the default project.
Enter a Display Name.
You can enter a user-friendly name with spaces in this field.
Enter a Name.
The name is mandatory and can only contain lowercase, alphanumeric characters, and dashes (for example, my-project-1). Nobl9 duplicates the display name here, transforming it into the supported format, but you can edit the result.
Enter a Description.
Here you can add details such as who is responsible for the integration (team/owner) and the purpose of creating it.
Specify the Query delay to set a customized delay for queries when pulling the data from the data source.
- The default value in Prometheus integration for Query delay is 0 seconds.
info
Changing the Query delay may affect your SLI data. For more details, check the Query delay documentation.
Enter a Maximum Period for Historical Data Retrieval.
- This value defines how far back in the past your data will be retrieved when replaying your SLO based on this data source.
- The maximum period value depends on the data source.
  Find the maximum value for your data source.
- A greater period can extend the loading time when creating an SLO.
Enter a Default Period for Historical Data Retrieval.
- It is used by SLOs connected to this data source.
- The value must be a positive integer or 0.
- By default, this value is set to 0. When you set it to >0, you will create SLOs with Replay.
Click Add Data Source.

Deploy your agent in a Kubernetes cluster or Docker container.

💡Custom HTTP headers

When you need to set custom HTTP headers in your Nobl9 agent, include them in your agent deployment.

sloctl

Create a YAML definition to set up an agent connection with Prometheus. For this, refer to the following example:

YAML definition for the agent connection method
apiVersion: n9/v1alpha
kind: Agent
metadata:
  name: prometheus
  displayName: Prometheus Agent
  project: default
spec:
  description: Example Prometheus Agent
  releaseChannel: stable
  prometheus:
    url: http://prometheus.prometheus:9090
  historicalDataRetrieval:
    maxDuration:
      value: 30
      unit: Day
    defaultDuration:
      value: 15
      unit: Day
  queryDelay:
    value: 1
    unit: Second

Field	Type	Description
`queryDelay.unit` mandatory	enum	Specifies the unit for the query delay. Possible values: `Second` \| `Minute`. • Check query delay documentation for default unit of query delay for each source.
`queryDelay.value` mandatory	numeric	Specifies the value for the query delay. • Must be a number less than 1440 minutes (24 hours). • Check query delay documentation for default unit of query delay for each source.
`releaseChannel` mandatory	enum	Specifies the release channel. Accepted values: `beta` \| `stable`.
Source-specific fields
`prometheus.url` mandatory	string	Base URL to Prometheus server. See authentication section above for more details.
Replay-related fields
`historicalDataRetrieval` optional	n/a	Optional structure related to configuration related to Replay. ❗ Use only with supported sources. • If omitted, Nobl9 uses the default values of `value: 0` and `unit: Day` for `maxDuration` and `defaultDuration`.
`maxDuration.value` optional	numeric	Specifies the maximum duration for historical data retrieval. Must be integer `≥ 0`. See Replay documentation for values of max duration per data source.
`maxDuration.unit` optional	enum	Specifies the unit for the maximum duration of historical data retrieval. Accepted values: `Minute` \| `Hour` \| `Day`.
`defaultDuration.value` optional	numeric	Specifies the default duration for historical data retrieval. Must be integer `≥ 0` and `≤` `maxDuration`.
`defaultDuration.unit` optional	enum	Specifies the unit for the default duration of historical data retrieval. Accepted values: `Minute` \| `Hour` \| `Day`.

Apply your YAML definition using the sloctl apply command.
Deploy your agent in a Kubernetes cluster or Docker container.

💡Custom HTTP headers

When you need to set custom HTTP headers in your Nobl9 agent, include them in your agent deployment.

Cortex support with Nobl9 Prometheus agent

Cortex | Cortex documentation is a database based on Prometheus with compatible API. Therefore, it is possible to use Cortex with the Nobl9 Prometheus agent.

Cortex cluster setup is out of the scope of this document and is described in the Cortex documentation. Cortex deployment can be simplified with the official Helm chart.

As described in Cortex Architecture | Cortex documentation, Prometheus API is exposed by the Nginx under default address <http://cortex-nginx/prometheus.> This address can be used as Prometheus URL in the agent configuration panel. The default Prometheus endpoint can be changed according to the API documentation | Cortex documentation. In that case, the agent needs to access the /api/v1/query_range endpoint.

If you want the Nobl9 agent to support a multi-tenancy deployment mode in Cortex, use the following environment variable while deploying Nobl9 agent in Kubernetes (see section above):

          env:
            - name: PROMETHEUS_X_SCOPE_ORG_ID
              value: <X-Scope-OrgID>

of in your Docker deployment:

docker run -d --restart on-failure \
  --name nobl9-agent-nobl9-dev-stable-prometheus \
  -e PROMETHEUS_X_SCOPE_ORG_ID="<X-Scope-OrgID>"

Grafana Cloud support with Nobl9 Prometheus agent

Grafana Cloud is an observability platform that leverages Prometheus by directly interacting with the Prometheus HTTP API | Prometheus documentation. Therefore, it is possible to use Grafana Cloud with the Nobl9 Prometheus agent.

To use Grafana Cloud with Prometheus, you must authenticate your Prometheus agent with the basic_auth proxy. Refer to the section above for more details.

As described in Analyzing metrics usage with the Prometheus API | Grafana Cloud documentation, Prometheus API is exposed through the /api/prom/api/v1/query_range endpoint which is accessed by the Nobl9 agent.

To use Grafana Cloud with Nobl9, you need to append /api/prom/ to the end of the URL you configure your Grafana Source in the Data source wizard for a regular Prometheus data integration. Thus, instead of http://HOST/, you need to enter http://HOST/api/prom/ in the Data source wizard.

For more details, check Grafana Cloud documentation.