alertmanager.yaml

global:
  resolve_timeout: 5m
  slack_api_url: '<SLACK_URL_HERE>'
route:
  group_by: [alertname, job]
  receiver: default
receivers:
- name: default
  slack_configs:
  - api_url: '<SLACK_URL_HERE>'
    username: 'Alertmanager'
    channel: '#test-prometheus'
    send_resolved: true
    title: |-
      [{{ .Status | toUpper }}{{ if eq .Status "firing" }}:{{ .Alerts.Firing | len }}{{ end }}] {{ .CommonLabels.alertname }} for {{ .CommonLabels.job }}
      {{- if gt (len .CommonLabels) (len .GroupLabels) -}}
        {{" "}}(
        {{- with .CommonLabels.Remove .GroupLabels.Names }}
          {{- range $index, $label := .SortedPairs -}}
            {{ if $index }}, {{ end }}
            {{- $label.Name }}="{{ $label.Value -}}"
          {{- end }}
        {{- end -}}
        )
      {{- end }}
    text: >-
      {{ with index .Alerts 0 -}}
        :chart_with_upwards_trend: *<{{ .GeneratorURL }}|Graph>*
        {{- if .Annotations.runbook }}   :notebook: *<{{ .Annotations.runbook }}|Runbook>*{{ end }}
      {{ end }}

      *Alert details*:

      {{ range .Alerts -}}
        *Alert:* {{ .Annotations.title }}{{ if .Labels.severity }} - `{{ .Labels.severity }}`{{ end }}
      *Description:* {{ .Annotations.description }}
      *Details:*
        {{ range .Labels.SortedPairs }} • *{{ .Name }}:* `{{ .Value }}`
        {{ end }}
      {{ end }}