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configuration.md

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Configuration

Alertmanager Actions is an Alertmanager Receiver. The first step to use it would be deploy it.

Deploy Alertmanager Actions

Kubernetes

There's a helm chart with some features. It has secrets and pre-installing tools support. Say you'd want to ssh to a machine to restart an nginx service when the alert NginxDown bumps. You'd define a values.yml like the next:

preInstall:
  enabled: true
  value: |
    apt update; apt install -y openssh-client

secrets:
  enabled: true
  values:
  - key: ssh-key
    value: SGksIHlvdSBjdXJpb3VzIHBlcnNvbiA6KQ==

config:
  alertmanager_actions: |
    - name: RestartNginx
      labels:
        alertname: NginxDown
        action: restart
      command:
        - ssh -o StrictHostKeyChecking=no -i /secrets/ssh-key ec2-user@$PRIVATE_IP sudo systemctl restart nginx

There's some stuff going here. First of all, pre-installing stuff. There's to ways of doing so, using a custom image with the Alertmanager or using the preInstall feature. Using the feature is pretty easy, you just activate the feature and then install what you need in the container. In the example, since we want to ssh to a box and restart a service, we only will need ssh.

Next, the secrets. It's possible to define a list of secrets. The value must be base64 encoded. The key will be the name of the file containing the secret. All secrets are mounted in the cointanier in /secrets/. So, the defined secret will be in a file in the container in /secrets/ssh-key.

The last part, the actions. In the example there's defined an action called NginxDown that will be activated if an alert with the labels alertname with value NginxDown and action with value restart are received. When received, it will execute the command. The command is pretty plain, but it has something special. The environmental variable $PRIVATE_IP. This is one of the strongest features, all alert labels are passed as environmental variables to the command. In the example, it's assumed that the triggered alert has one label called $PRIVATE_IP that contains the IP that can be used to reach the service.

Plain box

TBD

Configure the Alertmanager

The only part explained will be the one related to the receivers configuration. So the next pieces of code won't work as is, you'll need a working prometheus + alertmanager installation.

In this section there will be explained how to configure the route and the receiver. The first one will be the route:

route:
  routes:
  - receiver: alertmanager-actions
    match:
      actions: 'true'

This means that all alerts that the Alertmanager receive with the label actions with the value true will be redirected to the alertmanager-actions receiver.

The receiver itself is a webhook, its configuration it's pretty simple:

receivers:
- name: alertmanager-actions
  webhook_configs:
  - send_resolved: false
    url: "http://alertmanager-actions/"

Configure the alert

Again, the only part explained will be the one related to alert configuration. So the next pieces of code won't work as is, you'll need a working prometheus + alertmanager installation.

The next section is the configuration of an alert:

groups:
- name: ipsec.rules
  rules:
  - alert: RestartNginx
    expr: nginx_down == 0
    labels:
      action: restart
    annotations:
      description: The proxy is down, will try to restart it automatically.
    for: 30s