Alerting: Fix email template for text/plain emails (#69951)

This commit fixes the email template for text/plain emails to
support custom messages. It also fixes the default template,
removing extra whitespace and showing Summary and Description
annotations separate from the other annotations.

emails/templates/ng_alert_notification.txt

@@ -1,38 +1,62 @@
-[[HiddenSubject .Subject "[[.Title]]"]]
+[[- define "__default_message" -]]
+You have [[ len .Alerts.Firing ]] firing alert(s), and [[ len .Alerts.Resolved ]] resolved alert(s) for [[ .GroupLabels ]]
 
-[[.Title]]
-----------------
+[[ if .Alerts.Firing -]]
+([[ len .Alerts.Firing ]]) FIRING
+-----------
+[[ template "__default_alerts_summarize" .Alerts.Firing ]]
+[[- end ]]
 
-[[ .Alerts | len ]] alert[[ if gt (len .Alerts) 1 ]]s[[ end ]] for
-[[ range .GroupLabels.SortedPairs ]]
-[[ .Name ]] = [[ .Value ]]
-[[ end ]]
-[[ if gt (len .Alerts.Firing) 0 ]]([[ .Alerts.Firing | len ]]) Firing[[ end ]]
-[[ range .Alerts.Firing ]]
-Labels:
-[[ range .Labels.SortedPairs ]]
-[[ .Name ]] = [[ .Value ]]
-[[ end ]]
-[[ if gt (len .Annotations) 0 ]]
-Annotations:
-[[ end ]]
-[[ range .Annotations.SortedPairs ]]
-[[ .Name ]] = [[ .Value ]]
-[[ end ]]
-[[ end ]][[ if gt (len .Alerts.Resolved) 0 ]]([[ .Alerts.Resolved | len ]]) Resolved[[ end ]]
-[[ range .Alerts.Resolved ]]
-Labels:
-[[ range .Labels.SortedPairs ]]
-[[ .Name ]] = [[ .Value ]]
-[[ end ]]
-[[ if gt (len .Annotations) 0 ]]
-Annotations:
-[[ end ]]
-[[ range .Annotations.SortedPairs ]]
-[[ .Name ]] = [[ .Value ]]
-[[ end ]]
-[[ end ]]View your Alert rule:
-[[.RuleUrl]]
+[[ if .Alerts.Resolved -]]
+([[ len .Alerts.Resolved ]]) RESOLVED
+-------------
+[[ template "__default_alerts_summarize" .Alerts.Resolved ]]
+[[- end ]]
+Go to the Alerts page: [[ .AlertPageUrl ]]
+[[- end -]]
 
-Go to the Alerts page:
-[[.AlertPageUrl]]
+[[- define "__default_alerts_summarize" -]]
+[[- range . ]]
+[[ template "__default_alert_labels" . ]]
+[[ template "__default_alert_annotations" . ]]
+[[- end ]]
+[[- end -]]
+
+[[- define "__default_alert_labels" -]]
+[[- if gt (len .Labels) 3 -]]
+Labels: [[ template "__default_sorted_pairs" .Labels ]]
+[[- else -]]
+Labels: [[ .Labels.SortedPairs ]]
+[[- end -]]
+[[- end -]]
+
+[[- define "__default_alert_annotations" -]]
+[[- $annotations := .Annotations -]]
+[[- if index $annotations "summary" -]]
+Summary: [[ index .Annotations "summary" ]]
+[[- $annotations = $annotations.Remove (toStrings (list "summary")) ]]
+[[ end -]]
+[[- if index $annotations "description" -]]
+Description: [[ index $annotations "description" ]]
+[[- $annotations = $annotations.Remove (toStrings (list "description")) ]]
+[[ end -]]
+[[- if index $annotations "runbook_url" -]]
+Runbook: [[ index $annotations "runbook_url" ]]
+[[- $annotations = $annotations.Remove (toStrings (list "runbook_url")) ]]
+[[ end -]]
+[[- if $annotations -]]
+Annotations: [[ template "__default_sorted_pairs" $annotations ]]
+[[ end -]]
+[[- end -]]
+
+[[- define "__default_sorted_pairs" -]]
+[[ range .SortedPairs ]]
+    [[ .Name ]] = [[ .Value ]]
+[[- end ]]
+[[- end -]]
+
+[[- if .Message -]]
+    [[ .Message ]]
+[[ else -]]
+    [[ template "__default_message" . ]]
+[[- end ]]

public/emails/ng_alert_notification.txt

@@ -1,41 +1,64 @@
-{{HiddenSubject .Subject "{{.Title}}"}}
+{{- define "__default_message" -}}
+You have {{ len .Alerts.Firing }} firing alert(s), and {{ len .Alerts.Resolved }} resolved alert(s) for {{ .GroupLabels }}
 
-{{.Title}}
-----------------
+{{ if .Alerts.Firing -}}
+({{ len .Alerts.Firing }}) FIRING
+-----------
+{{ template "__default_alerts_summarize" .Alerts.Firing }}
+{{- end }}
 
-{{ .Alerts | len }} alert{{ if gt (len .Alerts) 1 }}s{{ end }} for
-{{ range .GroupLabels.SortedPairs }}
-{{ .Name }} = {{ .Value }}
-{{ end }}
-{{ if gt (len .Alerts.Firing) 0 }}({{ .Alerts.Firing | len }}) Firing{{ end }}
-{{ range .Alerts.Firing }}
-Labels:
-{{ range .Labels.SortedPairs }}
-{{ .Name }} = {{ .Value }}
-{{ end }}
-{{ if gt (len .Annotations) 0 }}
-Annotations:
-{{ end }}
-{{ range .Annotations.SortedPairs }}
-{{ .Name }} = {{ .Value }}
-{{ end }}
-{{ end }}{{ if gt (len .Alerts.Resolved) 0 }}({{ .Alerts.Resolved | len }}) Resolved{{ end }}
-{{ range .Alerts.Resolved }}
-Labels:
-{{ range .Labels.SortedPairs }}
-{{ .Name }} = {{ .Value }}
-{{ end }}
-{{ if gt (len .Annotations) 0 }}
-Annotations:
-{{ end }}
-{{ range .Annotations.SortedPairs }}
-{{ .Name }} = {{ .Value }}
-{{ end }}
-{{ end }}View your Alert rule:
-{{.RuleUrl}}
+{{ if .Alerts.Resolved -}}
+({{ len .Alerts.Resolved }}) RESOLVED
+-------------
+{{ template "__default_alerts_summarize" .Alerts.Resolved }}
+{{- end }}
+Go to the Alerts page: {{ .AlertPageUrl }}
+{{- end -}}
 
-Go to the Alerts page:
-{{.AlertPageUrl}}
+{{- define "__default_alerts_summarize" -}}
+{{- range . }}
+{{ template "__default_alert_labels" . }}
+{{ template "__default_alert_annotations" . }}
+{{- end }}
+{{- end -}}
 
+{{- define "__default_alert_labels" -}}
+{{- if gt (len .Labels) 3 -}}
+Labels: {{ template "__default_sorted_pairs" .Labels }}
+{{- else -}}
+Labels: {{ .Labels.SortedPairs }}
+{{- end -}}
+{{- end -}}
+
+{{- define "__default_alert_annotations" -}}
+{{- $annotations := .Annotations -}}
+{{- if index $annotations "summary" -}}
+Summary: {{ index .Annotations "summary" }}
+{{- $annotations = $annotations.Remove (toStrings (list "summary")) }}
+{{ end -}}
+{{- if index $annotations "description" -}}
+Description: {{ index $annotations "description" }}
+{{- $annotations = $annotations.Remove (toStrings (list "description")) }}
+{{ end -}}
+{{- if index $annotations "runbook_url" -}}
+Runbook: {{ index $annotations "runbook_url" }}
+{{- $annotations = $annotations.Remove (toStrings (list "runbook_url")) }}
+{{ end -}}
+{{- if $annotations -}}
+Annotations: {{ template "__default_sorted_pairs" $annotations }}
+{{ end -}}
+{{- end -}}
+
+{{- define "__default_sorted_pairs" -}}
+{{ range .SortedPairs }}
+    {{ .Name }} = {{ .Value }}
+{{- end }}
+{{- end -}}
+
+{{- if .Message -}}
+    {{ .Message }}
+{{ else -}}
+    {{ template "__default_message" . }}
+{{- end }}
 
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