# =============================================================================
# Alertmanager -- routage des alertes vers Discord
# =============================================================================
# L'URL du webhook n'est PAS dans ce ConfigMap : elle est lue depuis un fichier
# monte depuis un Secret (webhook_url_file). Un ConfigMap est lisible par tout
# ce qui a un acces lecture au namespace, un webhook Discord permet de publier
# n'importe quoi dans votre canal d'exploitation.
---
apiVersion: v1
kind: ConfigMap
metadata:
  name: alertmanager-config
  namespace: monitoring
data:
  alertmanager.yml: |
    global:
      resolve_timeout: 5m

    route:
      receiver: discord
      group_by: ['alertname', 'severity']
      group_wait: 30s
      group_interval: 5m
      # Une alerte critique non traitee est repetee toutes les heures : elle ne
      # doit pas disparaitre du fil de discussion.
      repeat_interval: 1h
      routes:
        - matchers:
            - severity = "avertissement"
          receiver: discord
          repeat_interval: 12h

    inhibit_rules:
      # Si le backend est totalement indisponible, inutile d'inonder le canal
      # avec les alertes de latence et de taux d'erreur qui en decoulent.
      - source_matchers:
          - alertname = "BackendIndisponible"
        target_matchers:
          - severity =~ "avertissement|critique"
        equal: ['cluster']

    receivers:
      - name: discord
        discord_configs:
          - webhook_url_file: /etc/alertmanager/secrets/discord-webhook
            send_resolved: true
            title: '[{{ .Status | toUpper }}] {{ .CommonLabels.alertname }}'
            message: |-
              {{ range .Alerts }}{{ .Annotations.summary }}
              {{ .Annotations.description }}
              {{ end }}
---
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: alertmanager-data
  namespace: monitoring
spec:
  accessModes: [ReadWriteOnce]
  storageClassName: local-path
  resources:
    requests:
      storage: 1Gi
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: alertmanager
  namespace: monitoring
  labels:
    app.kubernetes.io/name: alertmanager
spec:
  replicas: 1
  strategy:
    type: Recreate
  selector:
    matchLabels:
      app.kubernetes.io/name: alertmanager
  template:
    metadata:
      labels:
        app.kubernetes.io/name: alertmanager
    spec:
      securityContext:
        runAsNonRoot: true
        runAsUser: 65534
        runAsGroup: 65534
        fsGroup: 65534
        seccompProfile:
          type: RuntimeDefault
      containers:
        - name: alertmanager
          image: prom/alertmanager:v0.28.0
          args:
            - --config.file=/etc/alertmanager/alertmanager.yml
            - --storage.path=/alertmanager
            - --web.listen-address=:9093
          ports:
            - name: http
              containerPort: 9093
          readinessProbe:
            httpGet:
              path: /-/ready
              port: http
            initialDelaySeconds: 10
          resources:
            requests:
              cpu: 20m
              memory: 64Mi
            limits:
              cpu: 200m
              memory: 192Mi
          securityContext:
            allowPrivilegeEscalation: false
            readOnlyRootFilesystem: true
            capabilities:
              drop: ["ALL"]
          volumeMounts:
            - name: config
              mountPath: /etc/alertmanager/alertmanager.yml
              subPath: alertmanager.yml
            - name: secrets
              mountPath: /etc/alertmanager/secrets
              readOnly: true
            - name: data
              mountPath: /alertmanager
      volumes:
        - name: config
          configMap:
            name: alertmanager-config
        - name: secrets
          secret:
            secretName: alertmanager-secrets
        - name: data
          persistentVolumeClaim:
            claimName: alertmanager-data
---
apiVersion: v1
kind: Service
metadata:
  name: alertmanager
  namespace: monitoring
spec:
  type: ClusterIP
  selector:
    app.kubernetes.io/name: alertmanager
  ports:
    - name: http
      port: 9093
      targetPort: http