support for generating slack receivers with buttons for alerts (#256)

* support for generating slack receivers with buttons for alerts

Author: sandeepsukhani

prometheus-ksonnet/lib/alertmanager.libsonnet

@@ -17,20 +17,48 @@
     ]
   else [],
 
+  build_slack_receiver(name, slack_channel)::
+    {
+      name: name,
+      slack_configs: [{
+        api_url: $._config.slack_url,
+        channel: slack_channel,
+        send_resolved: true,
+        title: '{{ template "__alert_title" . }}',
+        text: '{{ template "__alert_text" . }}',
+        actions: [
+          {
+            type: 'button',
+            text: 'Runbook :green_book:',
+            url: '{{ (index .Alerts 0).Annotations.runbook_url }}',
+          },
+          {
+            type: 'button',
+            text: 'Source :information_source:',
+            url: '{{ (index .Alerts 0).GeneratorURL }}',
+          },
+          {
+            type: 'button',
+            text: 'Silence :no_bell:',
+            url: '{{ template "__alert_silence_link" . }}',
+          },
+        ],
+      }],
+    },
+
   alertmanager_config:: {
-    templates: ['/etc/alertmanager/*.tmpl'],
+    templates: [
+      '/etc/alertmanager/*.tmpl',
+      '/etc/alertmanager/config/templates.tmpl',
+    ],
     route: {
       group_by: ['alertname'],
       receiver: 'slack',
     },
 
-    receivers: [{
-      name: 'slack',
-      slack_configs: [{
-        api_url: $._config.slack_url,
-        channel: $._config.slack_channel,
-      }],
-    }],
+    receivers: [
+      $.build_slack_receiver('slack', $._config.slack_channel),
+    ],
   },
 
   local configMap = $.core.v1.configMap,
@@ -40,6 +68,7 @@
     configMap.new('alertmanager-config') +
     configMap.withData({
       'alertmanager.yml': $.util.manifestYaml($.alertmanager_config),
+      'templates.tmpl': (importstr 'files/alertmanager_config.tmpl'),
     })
   else {},
 

prometheus-ksonnet/lib/files/alertmanager_config.tmpl

@@ -0,0 +1,25 @@
+{{ define "__alert_title" -}}
+    [{{ .Status | toUpper }}{{ if eq .Status "firing" }}:{{ .Alerts.Firing | len }}{{ end }}] {{ .GroupLabels.cluster }}: {{ .GroupLabels.alertname }} ({{ .GroupLabels.namespace }})
+{{- end }}
+
+{{ define "__alert_text" -}}
+{{ .CommonAnnotations.summary }}
+{{ if .Alerts.Firing | len }}Firing alerts:
+{{ range .Alerts.Firing }}- {{ .Annotations.message }}{{ .Annotations.description }}
+{{ end }}{{ end }}{{ if .Alerts.Resolved | len }}Resolved alerts:
+{{ range .Alerts.Resolved }}- {{ .Annotations.message }}{{ .Annotations.description }}
+{{ end }}{{ end }}
+{{- end }}
+
+# This builds the silence URL.  We exclude the alertname in the range
+# to avoid the issue of having trailing comma separator (%2C) at the end
+# of the generated URL. Inspired from https://gist.github.com/milesbxf/e2744fc90e9c41b47aa47925f8ff6512
+{{ define "__alert_silence_link" -}}
+    {{ .ExternalURL }}/#/silences/new?filter=%7B
+    {{- range .CommonLabels.SortedPairs -}}
+        {{- if ne .Name "alertname" -}}
+            {{- .Name }}%3D"{{- .Value -}}"%2C%20
+        {{- end -}}
+    {{- end -}}
+    alertname%3D"{{ .CommonLabels.alertname }}"%7D
+{{- end }}