Enhance Telegram alert template: add handling for resolved alerts and improve message formatting

terraform/apps/prod-01/resources/telegram.tpl

@@ -1,4 +1,16 @@
-{{/* Always produce a non-empty message. Handles single or multiple firing alerts and missing username. */}}
+{{- /* Resolved alerts (if any) */ -}}
+{{- if gt (len .Alerts.Resolved) 1 -}}
+<b>{{ len .Alerts.Resolved }} logins resolved</b> on {{ with .CommonLabels.cluster }}<b>{{ . }}</b>{{ else }}<b>unknown host</b>{{ end }}:
+{{- range .Alerts.Resolved }}
+• {{ with .Labels.username }}<b>{{ . }}</b>{{ else }}<i>unknown</i>{{ end }} — Source: <code>{{ with .Labels.source }}{{ . }}{{ else }}?{{ end }}</code>{{ with .Labels.method }}, Method: <code>{{ . }}</code>{{ else }}, Method: <code>?</code>{{ end }}
+{{- end }}
+{{- else if eq (len .Alerts.Resolved) 1 -}}
+{{ $a := index .Alerts.Resolved 0 -}}
+<b>Resolved login:</b> {{ with $a.Labels.username }}<b>{{ . }}</b>{{ else }}<i>unknown</i>{{ end }} on <b>{{ $a.Labels.cluster }}</b>
+Source: <code>{{ with $a.Labels.source }}{{ . }}{{ else }}?{{ end }}</code>{{ with $a.Labels.method }}, Method: <code>{{ . }}</code>{{ else }}, Method: <code>?</code>{{ end }}
+{{- end -}}
+
+{{- /* Firing alerts (original logic) */ -}}
 {{ if gt (len .Alerts.Firing) 1 -}}
 <b>{{ len .Alerts.Firing }} logins</b> on {{ with .CommonLabels.cluster }}<b>{{ . }}</b>{{ else }}<b>unknown host</b>{{ end }}:
 {{- range .Alerts.Firing }}
@@ -9,5 +21,8 @@
 <b>Login:</b> {{ with $a.Labels.username }}<b>{{ . }}</b>{{ else }}<i>unknown</i>{{ end }} on <b>{{ $a.Labels.cluster }}</b>
 Source: <code>{{ with $a.Labels.source }}{{ . }}{{ else }}?{{ end }}</code>{{ with $a.Labels.method }}, Method: <code>{{ . }}</code>{{ else }}, Method: <code>?</code>{{ end }}
 {{ else -}}
+{{- /* If there were resolved alerts above this will still show when no firing alerts exist. */ -}}
+{{ if eq (len .Alerts.Resolved) 0 -}}
 <b>Login detected</b> — details unavailable.
+{{ end -}}
 {{ end -}}