The Alertmanager Config Secret contains the configuration of an Alertmanager instance that sends out notifications based on alerts it receives from Prometheus.

• Overview
  • Connecting Routes and PrometheusRules
• Creating Receivers in the Rancher UI
• Receiver Configuration
  • Slack
  • Email
  • PagerDuty
  • Opsgenie
  • Webhook
  • Custom
• Route Configuration
  • Receiver
  • Grouping
  • Matching
• Example Alertmanager Config
• Example Route Config for CIS Scan Alerts

Overview

By default, Rancher Monitoring deploys a single Alertmanager onto a cluster that uses a default Alertmanager Config Secret. As part of the chart deployment options, you can opt to increase the number of replicas of the Alertmanager deployed onto your cluster that can all be managed using the same underlying Alertmanager Config Secret.

This Secret should be updated or modified any time you want to:

• Add in new notifiers or receivers
• Change the alerts that should be sent to specific notifiers or receivers
• Change the group of alerts that are sent out

By default, you can either choose to supply an existing Alertmanager Config Secret (i.e. any Secret in the cattle-monitoring-system namespace) or allow Rancher Monitoring to deploy a default Alertmanager Config Secret onto your cluster. By default, the Alertmanager Config Secret created by Rancher will never be modified / deleted on an upgrade / uninstall of the rancher-monitoring chart to prevent users from losing or overwriting their alerting configuration when executing operations on the chart.

For more information on what fields can be specified in this secret, please look at the Prometheus Alertmanager docs.

The full spec for the Alertmanager configuration file and what it takes in can be found here.

For more information, refer to the official Prometheus documentation about configuring routes.

Connecting Routes and PrometheusRules

When you define a Rule (which is declared within a RuleGroup in a PrometheusRule resource), the spec of the Rule itself contains labels that are used by Prometheus to figure out which Route should receive this Alert. For example, an Alert with the label team: front-end will be sent to all Routes that match on that label.

Creating Receivers in the Rancher UI

Available as of v2.5.4

Prerequisites:

• The monitoring application needs to be installed.
• If you configured monitoring with an existing Alertmanager Secret, it must have a format that is supported by Rancher’s UI. Otherwise you will only be able to make changes based on modifying the Alertmanager Secret directly. Note: We are continuing to make enhancements to what kinds of Alertmanager Configurations we can support using the Routes and Receivers UI, so please file an issue if you have a request for a feature enhancement.

To create notification receivers in the Rancher UI,

1. Click Cluster Explorer > Monitoring and click Receiver.
2. Enter a name for the receiver.
3. Configure one or more providers for the receiver. For help filling out the forms, refer to the configuration options below.
4. Click Create.

Result: Alerts can be configured to send notifications to the receiver(s).

Receiver Configuration

The notification integrations are configured with the receiver, which is explained in the Prometheus documentation.

Rancher v2.5.4 introduced the capability to configure receivers by filling out forms in the Rancher UI.

Route Configuration

match:
  [ <labelname>: <labelvalue>, ... ]

match_re:
  [ <labelname>: <regex>, ... ]

Example Alertmanager Config

To set up notifications via Slack, the following Alertmanager Config YAML can be placed into the alertmanager.yaml key of the Alertmanager Config Secret, where the api_url should be updated to use your Webhook URL from Slack:

route:  
  group_by: ['job']
  group_wait: 30s
  group_interval: 5m
  repeat_interval: 3h 
  receiver: 'slack-notifications'
receivers:
- name: 'slack-notifications'
  slack_configs:
  - send_resolved: true
    text: '{{ template "slack.rancher.text" . }}'
    api_url: <user-provided slack webhook url here>
templates:
- /etc/alertmanager/config/*.tmpl

Example Route Config for CIS Scan Alerts

While configuring the routes for rancher-cis-benchmark alerts, you can specify the matching using the key-value pair job: rancher-cis-scan.

For example, the following example route configuration could be used with a Slack receiver named test-cis:

spec:
  receiver: test-cis
  group_by:
#    - string
  group_wait: 30s
  group_interval: 30s
  repeat_interval: 30s
  match:
    job: rancher-cis-scan
#    key: string
  match_re:
    {}
#    key: string

For more information on enabling alerting for rancher-cis-benchmark, see this section.