example external custom alertmanager template

examples/alertmanager-alert-template.tmpl

+# to know more about custom template language read alertmanager documentation
+# inspired by : https://gist.github.com/milesbxf/e2744fc90e9c41b47aa47925f8ff6512
+
+{{ define "slack.title" -}}
+    [{{ .Status | toUpper -}}
+    {{ if eq .Status "firing" }}:{{ .Alerts.Firing | len }}{{- end -}}
+    ] {{ template "__alert_severity_prefix_title" . }} {{ .CommonLabels.alertname }}
+{{- end }}
+
+{{ define "slack.color" -}}
+    {{ if eq .Status "firing" -}}
+        {{ if eq .CommonLabels.severity "warning" -}}
+            warning
+        {{- else if eq .CommonLabels.severity "critical" -}}
+            danger
+        {{- else -}}
+            #439FE0
+        {{- end -}}
+    {{ else -}}
+    good
+    {{- end }}
+{{- end }}
+
+{{ define "slack.icon_emoji" }}:prometheus:{{ end }}
+
+{{/* The test to display in the alert */}}
+  {{ define "slack.text" -}}
+    {{ range .Alerts }}
+        {{- if .Annotations.message }}
+            {{ .Annotations.message }}
+        {{- end }}
+        {{- if .Annotations.description }}
+            {{ .Annotations.description }}
+        {{- end }}
+    {{- end }}
+{{- end }}
+

examples/alertmanager-config-template-external.jsonnet

+local configmap(name, namespace, data) = {
+    apiVersion: "v1",
+    kind: "ConfigMap",
+    metadate : {
+        name: name,
+        namespace: namespace,
+    },
+    data: data,
+ };
+
+local kp = 
+    // different libsonnet imported
+  {
+      configmap+:: {
+          'alert-templates': configmap(
+          'alertmanager-alert-template.tmpl',
+          $._config.namespace, 
+          {"data": importstr 'alertmanager-alert-template.tmpl'},
+          )
+      },
+      alertmanager+:{
+            spec+:{
+                # the important field configmaps:
+                configMaps: ['alert-templates',], # goes to etc/alermanager/configmaps
+            },
+      },
+};
+{ [name + '-configmap']: kp.configmap[name] for name in std.objectFields(kp.configmap) }

examples/alertmanager-config-with-template.yaml

+# external alertmanager yaml
+global:
+  resolve_timeout: 10m
+  slack_api_url: url
+route:
+  group_by: ['job']
+  group_wait: 30s
+  group_interval: 5m
+  repeat_interval: 12h
+  receiver: 'null'
+  routes:
+  - match:
+      alertname: Watchdog
+    receiver: 'null'
+receivers:
+- name: 'null'
+- name: slack
+slack_configs:
+- channel: '#alertmanager-testing'
+  send_resolved: true
+   title: '{{ template "slack.title" . }}'
+    icon_emoji: '{{ template "slack.icon_emoji" . }}'
+    color: '{{ template "slack.color" . }}'
+    text: '{{ template "slack.text" . }}
+
+templates:
+- '/etc/alertmanager/configmaps/alertmanager-alert-template.tmpl'