alertmanager/templates/slack.tmpl

{{ define "slack.larkspur.title" -}}
[{{ .Status | toUpper }}:{{ .Alerts | len }}] {{ .CommonLabels.alertname }}
{{- end }}

{{ define "slack.larkspur.text" -}}
{{ range .Alerts -}}
*{{ .Labels.alertname }}* severity={{ .Labels.severity }}
{{ .Annotations.summary }}
{{ .Annotations.description }}
Runbook: {{ .Annotations.runbook_url }}
{{ end -}}
Alerts: {{ .Alerts | len }}
{{- end }}