home-network-k3s-impl/platform/monitoring/alerts.yaml

---
# Platform-health alert rules (docs/10, R-OBS-04). These complement the default node/kubernetes
# rules bundled by kube-prometheus-stack and add FIRST-CLASS alerts for the platform's own moving
# parts: nodes, Longhorn, Flux, cert-manager, networking/VPN, backups, identity, and the monitoring
# stack's own capacity ("don't let the monitor blind itself").
#
# Each rule maps to a docs/10 platform-health bullet and carries a severity (critical = page-worthy
# vs warning = degraded/capacity) plus enough annotation context (summary + runbook) to act.
#
# The `release: kube-prometheus-stack` label makes the operator's Prometheus select these rules
# (ruleSelector). Some expressions depend on exporters/ServiceMonitors owned by other workstreams
# (Flux, cert-manager, Longhorn, Velero, Keycloak, Cilium/Hubble ship their own metrics); the rules
# are authored to fire as soon as those series arrive. Metric names flagged TODO need confirming at
# bring-up against the deployed exporter.
#
# runbook_url points at a docs base; swap for the real runbook location when it exists.

# =====================================================================================
# Nodes
# =====================================================================================
apiVersion: monitoring.coreos.com/v1
kind: PrometheusRule
metadata:
  name: platform-health-nodes
  namespace: monitoring
  labels:
    release: kube-prometheus-stack
    platform-health: "true"
spec:
  groups:
    - name: platform-health.nodes
      rules:
        - alert: NodeExporterDown
          expr: up{job="node-exporter"} == 0
          for: 5m
          labels:
            severity: critical
          annotations:
            summary: "Node exporter down on {{ $labels.instance }}"
            description: "Prometheus cannot scrape node-exporter on {{ $labels.instance }} for 5m — the node may be down or unreachable."
            runbook_url: "https://${BASE_DOMAIN}/runbooks/node-down"
        - alert: NodeMemoryPressureHigh
          expr: (1 - (node_memory_MemAvailable_bytes / node_memory_MemTotal_bytes)) > 0.90
          for: 10m
          labels:
            severity: warning
          annotations:
            summary: "Memory pressure high on {{ $labels.instance }}"
            description: "Available memory below 10% for 10m on {{ $labels.instance }} — the ~22 GiB box is under pressure."
            runbook_url: "https://${BASE_DOMAIN}/runbooks/node-memory"
        - alert: NodeDiskFillingUp
          expr: |
            (node_filesystem_avail_bytes{fstype!~"tmpfs|overlay|squashfs"}
              / node_filesystem_size_bytes{fstype!~"tmpfs|overlay|squashfs"}) < 0.10
          for: 15m
          labels:
            severity: warning
          annotations:
            summary: "Disk filling up on {{ $labels.instance }} ({{ $labels.mountpoint }})"
            description: "Less than 10% free on {{ $labels.mountpoint }} of {{ $labels.instance }} for 15m."
            runbook_url: "https://${BASE_DOMAIN}/runbooks/node-disk"
        - alert: NodeCPUPressureHigh
          # PSI "some" for CPU = fraction of wall-clock time at least one task was stalled waiting to
          # run. <5% is healthy; sustained >15% means bursty workloads are queueing against the vCPU
          # cap (measured 15-23% at 6 vCPU before the 8-vCPU resize). Averaged CPU% (kubectl top) hides
          # this — PSI is the metric that actually surfaces the "spikes cause blips of delay" symptom.
          expr: rate(node_pressure_cpu_waiting_seconds_total[5m]) > 0.15
          for: 15m
          labels:
            severity: warning
          annotations:
            summary: "CPU pressure high on {{ $labels.instance }}"
            description: "CPU PSI (some) above 15% for 15m on {{ $labels.instance }} — tasks are being delayed waiting for CPU (bursts exceeding the node's vCPU headroom). Add vCPUs or trim CPU-heavy workloads."
            runbook_url: "https://${BASE_DOMAIN}/runbooks/node-cpu"
        - alert: NodeCPULoadHigh
          # 5-min load average per core. Sustained >1 means the run queue exceeds the core count (more
          # runnable/blocked tasks than CPUs). Core count = number of idle-mode cpu series per node.
          # Pair with NodeCPUPressureHigh to confirm the contention is CPU (vs I/O, which inflates load
          # but not CPU-PSI).
          expr: |
            node_load5
              / count without (cpu, mode) (node_cpu_seconds_total{mode="idle"}) > 1
          for: 15m
          labels:
            severity: warning
          annotations:
            summary: "Load per core high on {{ $labels.instance }}"
            description: "5-min load average per core above 1.0 for 15m on {{ $labels.instance }} — the node's run queue exceeds its core count."
            runbook_url: "https://${BASE_DOMAIN}/runbooks/node-cpu"

# =====================================================================================
# Storage — Longhorn
# =====================================================================================
---
apiVersion: monitoring.coreos.com/v1
kind: PrometheusRule
metadata:
  name: platform-health-longhorn
  namespace: monitoring
  labels:
    release: kube-prometheus-stack
    platform-health: "true"
spec:
  groups:
    - name: platform-health.longhorn
      rules:
        # longhorn_volume_robustness: 0=unknown 1=healthy 2=degraded 3=faulted
        - alert: LonghornVolumeDegraded
          expr: longhorn_volume_robustness == 2
          for: 10m
          labels:
            severity: warning
          annotations:
            summary: "Longhorn volume degraded: {{ $labels.volume }}"
            description: "Volume {{ $labels.volume }} has been degraded (replica rebuild / missing replica) for 10m."
            runbook_url: "https://${BASE_DOMAIN}/runbooks/longhorn-degraded"
        - alert: LonghornVolumeFaulted
          expr: longhorn_volume_robustness == 3
          for: 1m
          labels:
            severity: critical
          annotations:
            summary: "Longhorn volume FAULTED: {{ $labels.volume }}"
            description: "Volume {{ $labels.volume }} is faulted — data at risk / offline. Immediate attention required."
            runbook_url: "https://${BASE_DOMAIN}/runbooks/longhorn-faulted"
        - alert: LonghornVolumeCapacityHigh
          expr: (longhorn_volume_actual_size_bytes / longhorn_volume_capacity_bytes) > 0.85
          for: 30m
          labels:
            severity: warning
          annotations:
            summary: "Longhorn volume near capacity: {{ $labels.volume }}"
            description: "Volume {{ $labels.volume }} is over 85% used for 30m."
            runbook_url: "https://${BASE_DOMAIN}/runbooks/longhorn-capacity"
        - alert: LonghornNodeStorageHigh
          expr: (longhorn_node_storage_usage_bytes / longhorn_node_storage_capacity_bytes) > 0.85
          for: 30m
          labels:
            severity: warning
          annotations:
            summary: "Longhorn node storage near capacity: {{ $labels.node }}"
            description: "Longhorn node {{ $labels.node }} is over 85% of its storage capacity for 30m."
            runbook_url: "https://${BASE_DOMAIN}/runbooks/longhorn-capacity"

# =====================================================================================
# GitOps — Flux
# =====================================================================================
---
apiVersion: monitoring.coreos.com/v1
kind: PrometheusRule
metadata:
  name: platform-health-flux
  namespace: monitoring
  labels:
    release: kube-prometheus-stack
    platform-health: "true"
spec:
  groups:
    - name: platform-health.flux
      rules:
        - alert: FluxReconciliationFailure
          expr: |
            max by (namespace, name, kind) (
              gotk_reconcile_condition{type="Ready", status="False"}
            ) == 1
          for: 15m
          labels:
            severity: warning
          annotations:
            summary: "Flux resource not ready: {{ $labels.kind }}/{{ $labels.name }}"
            description: "{{ $labels.kind }} {{ $labels.namespace }}/{{ $labels.name }} has failed to reconcile (Ready=False) for 15m — GitOps drift/failure (R-GITOPS-03)."
            runbook_url: "https://${BASE_DOMAIN}/runbooks/flux-reconcile"
        - alert: FluxResourceSuspended
          expr: |
            max by (namespace, name, kind) (gotk_suspend_status) == 1
          for: 1h
          labels:
            severity: warning
          annotations:
            summary: "Flux resource suspended: {{ $labels.kind }}/{{ $labels.name }}"
            description: "{{ $labels.kind }} {{ $labels.namespace }}/{{ $labels.name }} has been suspended for 1h — reconciliation/drift-correction is off."
            runbook_url: "https://${BASE_DOMAIN}/runbooks/flux-suspended"

# =====================================================================================
# Certificates — cert-manager
# =====================================================================================
---
apiVersion: monitoring.coreos.com/v1
kind: PrometheusRule
metadata:
  name: platform-health-certificates
  namespace: monitoring
  labels:
    release: kube-prometheus-stack
    platform-health: "true"
spec:
  groups:
    - name: platform-health.certificates
      rules:
        - alert: CertificateExpiringSoon
          expr: (certmanager_certificate_expiration_timestamp_seconds - time()) < (14 * 24 * 3600)
          for: 1h
          labels:
            severity: warning
          annotations:
            summary: "Certificate expiring soon: {{ $labels.name }}"
            description: "Certificate {{ $labels.namespace }}/{{ $labels.name }} expires in under 14 days."
            runbook_url: "https://${BASE_DOMAIN}/runbooks/cert-expiry"
        - alert: CertificateExpiryImminent
          expr: (certmanager_certificate_expiration_timestamp_seconds - time()) < (3 * 24 * 3600)
          for: 1h
          labels:
            severity: critical
          annotations:
            summary: "Certificate expiry imminent: {{ $labels.name }}"
            description: "Certificate {{ $labels.namespace }}/{{ $labels.name }} expires in under 3 days and has not renewed."
            runbook_url: "https://${BASE_DOMAIN}/runbooks/cert-expiry"
        - alert: CertificateNotReady
          expr: certmanager_certificate_ready_status{condition="False"} == 1
          for: 1h
          labels:
            severity: warning
          annotations:
            summary: "Certificate not ready / issuance failing: {{ $labels.name }}"
            description: "Certificate {{ $labels.namespace }}/{{ $labels.name }} has been in a not-ready state for 1h (ACME issuance failure?)."
            runbook_url: "https://${BASE_DOMAIN}/runbooks/cert-issuance"

# =====================================================================================
# Networking — VPN / egress-gateway / denied flows (Hubble)
# =====================================================================================
---
apiVersion: monitoring.coreos.com/v1
kind: PrometheusRule
metadata:
  name: platform-health-networking
  namespace: monitoring
  labels:
    release: kube-prometheus-stack
    platform-health: "true"
spec:
  groups:
    - name: platform-health.networking
      rules:
        # VPN tunnel health (ADR-0015: node-level host OpenVPN tunnel on the egress-gateway node, steered
        # by Cilium Egress Gateway — there is NO in-cluster gateway pod). OpenVPN creates/destroys the tun0
        # device with the connection, so the tun0 netdev series exists iff the tunnel is up. node_network_up
        # is unreliable here (tun0 operstate=unknown => 0), so key on the byte-counter's PRESENCE. absent()
        # also fires if the gateway node / its node-exporter is down (the tun0 series goes stale), covering
        # gateway-node-down as well. Metric confirmed live on the dev cluster 2026-08-24.
        - alert: VPNTunnelDown
          expr: absent(node_network_receive_bytes_total{device="tun0"})
          for: 5m
          labels:
            severity: critical
          annotations:
            summary: "Egress VPN tunnel down"
            description: "The egress-gateway VPN tunnel is down (or its metric is absent) for 5m — outbound traffic could leak or stall (leak risk, docs/07)."
            runbook_url: "https://${BASE_DOMAIN}/runbooks/vpn-down"
        # (ADR-0015) The former `EgressGatewayUnhealthy` pod-readiness alert was REMOVED with the gluetun
        # retirement: there is no in-cluster egress-gateway pod anymore (the tunnel is a host systemd
        # service, steering is Cilium eBPF). Tunnel + gateway-node health is covered by `VPNTunnelDown`
        # above (tun0 presence, which also goes absent if the gateway node is down); Cilium datapath
        # health is covered by the Cilium platform alerts.
        - alert: HubbleDeniedFlowSpike
          # Cilium/Hubble denied (policy-drop) flows. Requires hubble metrics enabled (docs/03).
          expr: sum(rate(hubble_drop_total{reason="POLICY_DENIED"}[5m])) > 5
          for: 10m
          labels:
            severity: warning
          annotations:
            summary: "Spike in policy-denied network flows"
            description: "Policy-denied flow rate is elevated for 10m — a NetworkPolicy regression or an intrusion probe (security audit, docs/07)."
            runbook_url: "https://${BASE_DOMAIN}/runbooks/denied-flows"

# =====================================================================================
# Backups — Velero
# =====================================================================================
---
apiVersion: monitoring.coreos.com/v1
kind: PrometheusRule
metadata:
  name: platform-health-backups
  namespace: monitoring
  labels:
    release: kube-prometheus-stack
    platform-health: "true"
spec:
  groups:
    - name: platform-health.backups
      rules:
        - alert: VeleroBackupFailure
          expr: increase(velero_backup_failure_total[1h]) > 0
          for: 5m
          labels:
            severity: critical
          annotations:
            summary: "Velero backup failed: schedule {{ $labels.schedule }}"
            description: "One or more Velero backups failed in the last hour (R-STATE-03 — off-cluster DR at risk)."
            runbook_url: "https://${BASE_DOMAIN}/runbooks/backup-failure"
        - alert: VeleroBackupPartialFailure
          expr: increase(velero_backup_partial_failure_total[1h]) > 0
          for: 5m
          labels:
            severity: warning
          annotations:
            summary: "Velero backup partially failed"
            description: "A Velero backup completed with partial failures in the last hour — some resources/volumes were skipped."
            runbook_url: "https://${BASE_DOMAIN}/runbooks/backup-partial"
        - alert: VeleroNoRecentBackup
          expr: (time() - velero_backup_last_successful_timestamp{schedule!=""}) > (24 * 3600)
          for: 1h
          labels:
            severity: critical
          annotations:
            summary: "No successful Velero backup in 24h: {{ $labels.schedule }}"
            description: "Schedule {{ $labels.schedule }} has not produced a successful backup in over 24h (missed schedule)."
            runbook_url: "https://${BASE_DOMAIN}/runbooks/backup-missed"

# =====================================================================================
# Identity — Keycloak (SSO is a critical dependency — docs/15)
# =====================================================================================
---
apiVersion: monitoring.coreos.com/v1
kind: PrometheusRule
metadata:
  name: platform-health-identity
  namespace: monitoring
  labels:
    release: kube-prometheus-stack
    platform-health: "true"
spec:
  groups:
    - name: platform-health.identity
      rules:
        - alert: KeycloakDown
          # Scope to the Keycloak SERVER StatefulSet pods (keycloak-0, keycloak-1). The keycloak
          # namespace also holds the operator (keycloak-operator-*) and DB (keycloak-db-*) pods, so an
          # un-scoped max() would be masked by those being ready — this must reflect the IdP itself.
          expr: |
            max(kube_pod_status_ready{namespace="keycloak", pod=~"keycloak-[0-9]+", condition="true"}) == 0
            or absent(kube_pod_status_ready{namespace="keycloak", pod=~"keycloak-[0-9]+"})
          for: 5m
          labels:
            severity: critical
          annotations:
            summary: "Keycloak IdP down"
            description: "No ready Keycloak pod for 5m — SSO is unavailable and dependent services cannot authenticate (docs/15)."
            runbook_url: "https://${BASE_DOMAIN}/runbooks/keycloak-down"
        - alert: KeycloakDatabaseDown
          # Keycloak's PostgreSQL runs as a CloudNativePG Cluster `keycloak-db` (pods keycloak-db-N).
          # DR-critical, Longhorn-backed. (CNPG also exports cnpg_* metrics via its PodMonitor.)
          expr: |
            max(kube_pod_status_ready{namespace="keycloak", pod=~"keycloak-db-.*", condition="true"}) == 0
            or absent(kube_pod_status_ready{namespace="keycloak", pod=~"keycloak-db-.*"})
          for: 5m
          labels:
            severity: critical
          annotations:
            summary: "Keycloak database unavailable"
            description: "Keycloak's PostgreSQL is not ready for 5m — the IdP will fail (docs/15)."
            runbook_url: "https://${BASE_DOMAIN}/runbooks/keycloak-db"

# =====================================================================================
# The monitor's own capacity — don't let the monitor blind itself (docs/10)
# =====================================================================================
---
apiVersion: monitoring.coreos.com/v1
kind: PrometheusRule
metadata:
  name: platform-health-monitoring-self
  namespace: monitoring
  labels:
    release: kube-prometheus-stack
    platform-health: "true"
spec:
  groups:
    - name: platform-health.monitoring-self
      rules:
        - alert: MonitoringVolumeFillingUp
          expr: |
            (kubelet_volume_stats_available_bytes{namespace="monitoring"}
              / kubelet_volume_stats_capacity_bytes{namespace="monitoring"}) < 0.15
          for: 15m
          labels:
            severity: warning
          annotations:
            summary: "Monitoring PVC filling up: {{ $labels.persistentvolumeclaim }}"
            description: "PVC {{ $labels.persistentvolumeclaim }} (Prometheus/Loki) is under 15% free — retention/PVC size may need raising before the monitor goes blind."
            runbook_url: "https://${BASE_DOMAIN}/runbooks/monitoring-capacity"
        - alert: PrometheusTargetsMissing
          expr: |
            (count(up == 0) / count(up)) > 0.10
          for: 15m
          labels:
            severity: warning
          annotations:
            summary: "More than 10% of Prometheus targets are down"
            description: "Over 10% of scrape targets have been down for 15m — a broad monitoring blind spot."
            runbook_url: "https://${BASE_DOMAIN}/runbooks/targets-down"

# =====================================================================================
# Automated updates — Flux image-automation + hands-off update health (docs/11, ADR-0009)
#   R-UPD-02 (a failed/rolled-back update alerts) + R-OBS. All Flux controllers (incl. the image
#   reflector/automation + helm controllers) export the shared `gotk_reconcile_condition` /
#   `gotk_suspend_status` series; these rules add UPDATE-SPECIFIC visibility on top of the generic
#   platform-health.flux group so a silently-stalled or a rolled-back update is not missed.
# =====================================================================================
---
apiVersion: monitoring.coreos.com/v1
kind: PrometheusRule
metadata:
  name: platform-health-automated-updates
  namespace: monitoring
  labels:
    release: kube-prometheus-stack
    platform-health: "true"
spec:
  groups:
    - name: platform-health.automated-updates
      rules:
        # The write-back engine (ADR-0009) is broken → hands-off image updates SILENTLY stop advancing.
        - alert: ImageUpdateAutomationFailing
          expr: |
            max by (namespace, name) (
              gotk_reconcile_condition{kind="ImageUpdateAutomation", type="Ready", status="False"}
            ) == 1
          for: 30m
          labels:
            severity: warning
          annotations:
            summary: "Flux image-update-automation failing: {{ $labels.name }}"
            description: "ImageUpdateAutomation {{ $labels.namespace }}/{{ $labels.name }} cannot reconcile (git write-back) for 30m — stable image advances have stopped (R-UPD-02). Check the git write credential."
            runbook_url: "https://${BASE_DOMAIN}/runbooks/image-automation"
        # An ImagePolicy/ImageRepository can't resolve the latest stable tag (registry rate-limit /
        # auth / bad range) → that service stops receiving updates even though automation is healthy.
        - alert: ImagePolicyStalled
          expr: |
            max by (namespace, name, kind) (
              gotk_reconcile_condition{kind=~"ImagePolicy|ImageRepository", type="Ready", status="False"}
            ) == 1
          for: 1h
          labels:
            severity: warning
          annotations:
            summary: "Image scan/policy stalled: {{ $labels.kind }}/{{ $labels.name }}"
            description: "{{ $labels.kind }} {{ $labels.namespace }}/{{ $labels.name }} cannot resolve its stable tag for 1h (registry rate-limit / creds / range) — no longer receiving updates (R-UPD-01)."
            runbook_url: "https://${BASE_DOMAIN}/runbooks/image-policy-stalled"
        # A bad update was health-gated and AUTO-ROLLED-BACK (or is stuck mid-remediation). helm-controller
        # holds Ready=False while a failed upgrade remediates/rolls back to the last-good revision
        # (HelmRelease.spec.upgrade.remediation + .spec.rollback). This is the R-UPD-03 safety rail firing.
        # TODO(bring-up): tighten with the `reason` label (e.g. UpgradeFailed / RolledBack) once confirmed
        # against the deployed helm-controller metrics.
        - alert: UpdateHealthGateFailed
          expr: |
            max by (namespace, name) (
              gotk_reconcile_condition{kind="HelmRelease", type="Ready", status="False"}
            ) == 1
          for: 10m
          labels:
            severity: critical
          annotations:
            summary: "Update health-gate failed / rolled back: {{ $labels.name }}"
            description: "HelmRelease {{ $labels.namespace }}/{{ $labels.name }} failed its health-gated upgrade and is rolling back to the last-good revision (bad-update auto-rollback — R-UPD-03). Consider an `update.pin` escape hatch (docs/11)."
            runbook_url: "https://${BASE_DOMAIN}/runbooks/update-rollback"