Setting up Alertmanager

Since we are already using Prometheus, it makes sense to deploy Prometheus' companion Alertmanager. It will receive alerts, filter and forward them to the end-points we'll define. Slack will be the first.

Alertmanager Docker image expect us to define a configuration file that defines routes, receivers, and a few other things. One possible configuration can be as follows.

route: 
  receiver: "slack" 
  repeat_interval: 1h 
 
receivers: 
    - name: "slack" 
      slack_configs: 
          - send_resolved: true 
            text: "Something horrible happened! Run for your lives!" 
            api_url: "https://hooks.slack.com/services\
/T308SC7HD/B59ER97SS/S0KvvyStVnIt3ZWpIaLnqLCu" 

The configuration defines the route with slack as the receiver of the alerts. In the receivers section, we specified that we want resolved notifications (besides alerts), creative text, and the Slack API URL. As a result, alerts will be posted to the df-monitor-tests channel in DevOps20 team...