From e3c615b5c1ff63c0026bb22962a1b93343545078 Mon Sep 17 00:00:00 2001
From: Mayne0213 <bluemayne0213@icloud.com>
Date: Fri, 9 Jan 2026 15:09:43 +0900
Subject: [PATCH] FEAT(alertmanager): add OOMKilled alert rule

- Add PrometheusRule to alert when containers are OOMKilled
- Severity: warning, fires immediately
---
 alertmanager/kustomization.yaml            |  1 +
 alertmanager/manifests/oom-alert-rule.yaml | 21 +++++++++++++++++++++
 2 files changed, 22 insertions(+)
 create mode 100644 alertmanager/manifests/oom-alert-rule.yaml

diff --git a/alertmanager/kustomization.yaml b/alertmanager/kustomization.yaml
index 584d185..e02835a 100644
--- a/alertmanager/kustomization.yaml
+++ b/alertmanager/kustomization.yaml
@@ -3,3 +3,4 @@ kind: Kustomization
 resources:
 - manifests/servicemonitor.yaml
 - manifests/secret.yaml
+- manifests/oom-alert-rule.yaml
diff --git a/alertmanager/manifests/oom-alert-rule.yaml b/alertmanager/manifests/oom-alert-rule.yaml
new file mode 100644
index 0000000..04e840e
--- /dev/null
+++ b/alertmanager/manifests/oom-alert-rule.yaml
@@ -0,0 +1,21 @@
+apiVersion: monitoring.coreos.com/v1
+kind: PrometheusRule
+metadata:
+  name: oom-alerts
+  namespace: prometheus
+  labels:
+    app: kube-prometheus-stack
+    release: prometheus
+spec:
+  groups:
+  - name: oom.rules
+    rules:
+    - alert: KubeContainerOOMKilled
+      annotations:
+        description: "Container {{ $labels.container }} in pod {{ $labels.namespace }}/{{ $labels.pod }} was OOMKilled."
+        summary: "Container was OOMKilled"
+      expr: |
+        kube_pod_container_status_last_terminated_reason{reason="OOMKilled"} == 1
+      for: 0m
+      labels:
+        severity: warning