feat(prometheus): add alerting rules and alertmanager config

prometheus-stack/k8s/alertmanager-config.example.yaml

@@ -0,0 +1,38 @@
+route:
+  receiver: telegram
+  group_by:
+    - alertname
+    - namespace
+  group_wait: 30s
+  group_interval: 5m
+  repeat_interval: 12h
+  routes:
+    - receiver: null
+      matchers:
+        - alertname="InfoInhibitor"
+    - receiver: null
+      matchers:
+        - alertname="Watchdog"
+
+inhibit_rules:
+  - source_matchers:
+      - severity="critical"
+    target_matchers:
+      - severity=~"warning|info"
+    equal:
+      - namespace
+  - source_matchers:
+      - severity="warning"
+    target_matchers:
+      - severity="info"
+    equal:
+      - namespace
+
+receivers:
+  - name: telegram
+    telegram_configs:
+      - bot_token: REPLACE_WITH_TELEGRAM_BOT_TOKEN
+        chat_id: REPLACE_WITH_TELEGRAM_CHAT_ID
+        parse_mode: HTML
+        send_resolved: true
+  - name: null