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"
        # --- I/O PRESSURE (added after the 2026-09-07 k3s-prod-1 NotReady incident) ---------
        # THE METRIC THAT WOULD HAVE CALLED THE 2026-09-07 OUTAGE AND DID NOT EXIST.
        # At 06:05:21Z k3s-prod-1 went NotReady ("Kubelet stopped posting node status") with the
        # host up, pingable and SSH-able. Root cause was disk I/O starvation of the embedded etcd:
        #   slow fdatasync took=3.56s/6.71s/4.95s/3.40s (etcd expects 1s)
        #   apply request took too long took=8.30s (expects 100ms)
        #   etcdserver: too many requests
        # `/proc/pressure/io` FULL avg300 read 11.36 on k3s-prod-1 at the time, against 0.75 on
        # k3s-prod-2 (NVMe) and 1.29 on k3s-prod-3. The stack already alerted on CPU-PSI and
        # memory but had NO I/O alert at all, so the first signal the operator got was a node
        # already out of the cluster.
        #
        # WHY "full" AND NOT "some": node_pressure_io_stalled_seconds_total is PSI *full* — time
        # in which EVERY runnable task was blocked on I/O, i.e. the machine did no useful work.
        # `some` (node_pressure_io_waiting_seconds_total) is noisy on a storage node; `full` is
        # the one that tracked the outage.
        #
        # THRESHOLDS ARE MEASURED, NOT GUESSED. rate(...[5m]) is a 0-1 fraction, so the incident's
        # 11.36% is 0.1136 and the healthy steady state measured on the same node is ~0.01:
        #   warning  0.05 for 10m  — 5x steady state, well below the outage, leaves room to act
        #   critical 0.10 for 5m   — the level k3s-prod-1 actually sat at while etcd was stalling
        # Deliberately NOT scoped to prod: dev shares this file and its k3s VMs are HDD-backed,
        # where the same alert is if anything more likely to earn its keep.
        - alert: NodeIOPressureHigh
          expr: rate(node_pressure_io_stalled_seconds_total[5m]) > 0.05
          for: 10m
          labels:
            severity: warning
          annotations:
            summary: "Disk I/O pressure high on {{ $labels.instance }}"
            description: "I/O PSI (full) above 5% for 10m on {{ $labels.instance }} — every task on the node is spending real time blocked on disk. On a node whose etcd WAL shares a partition with Longhorn replicas this is the leading indicator of etcd fsync stalls. Check `cat /proc/pressure/io`, `iostat -x 1`, and whether Longhorn is rebuilding replicas."
            runbook_url: "https://${BASE_DOMAIN}/runbooks/node-io"
        - alert: NodeIOPressureCritical
          # 0.10 is the level k3s-prod-1 held while etcd logged multi-second fdatasync and then
          # dropped out of the cluster. At this point etcd is already at risk; do not wait 10m.
          expr: rate(node_pressure_io_stalled_seconds_total[5m]) > 0.10
          for: 5m
          labels:
            severity: critical
          annotations:
            summary: "Disk I/O starvation on {{ $labels.instance }}"
            description: "I/O PSI (full) above 10% for 5m on {{ $labels.instance }} — the level at which k3s-prod-1 stalled etcd's WAL fsync and went NotReady on 2026-09-07 while the host stayed up. Expect etcd 'slow fdatasync' / 'apply request took too long' in `journalctl -u k3s`. Stop or throttle whatever is writing (Longhorn rebuild, backup, restore) before the node drops."
            runbook_url: "https://${BASE_DOMAIN}/runbooks/node-io"

# =====================================================================================
# 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.
        #
        # FIXED 2026-09-06 — the bare `absent(...)` was evaluated CLUSTER-WIDE, so on a cluster with NO
        # egress-gateway node it could never clear. Prod has no gateway node, and this alert fired
        # continuously from 2026-09-05T21:23Z into `email-critical` — unbounded noise on the one channel
        # that must stay trustworthy. The expression is now GATED on the cluster actually being supposed
        # to have a tunnel, via two independent guards OR'd together:
        #
        #   1. A node carries `homelab.keithjackson.dev/egress-gateway=true` — the same label the
        #      CiliumEgressGatewayPolicy nodeSelector uses, so the alert is armed exactly when the
        #      steering datapath has a target. Requires the kube-state-metrics node-label allowlist
        #      enabled in kube-prometheus-stack.yaml (KSM exposes no custom labels by default). This is
        #      what makes a gateway-less cluster SELF-ARM the moment a gateway node is labelled — no
        #      manual re-enable to forget. The Node object survives a NotReady node, so this stays true
        #      while the gateway node is DOWN: gateway-node-down is still alerted.
        #   2. `tun0` was observed at all in the last hour — holds the alert armed through a
        #      kube-state-metrics outage, and keeps dev's behaviour unchanged even before/independently
        #      of the KSM rollout.
        #
        # `and on()` joins on the empty label set deliberately: absent() carries `device="tun0"` while the
        # guards carry no labels, so an unqualified `and` would never match. Both clauses verified live
        # against dev and prod Prometheus (read-only) on 2026-09-06: empty on prod (cannot fire), empty on
        # dev (tunnel up), and clause 2 already true on dev.
        - alert: VPNTunnelDown
          expr: |
            absent(node_network_receive_bytes_total{device="tun0"})
            and on()
            (
                (count(kube_node_labels{label_homelab_keithjackson_dev_egress_gateway="true"}) > 0)
              or
                (count(count_over_time(node_network_receive_bytes_total{device="tun0"}[1h])) > 0)
            )
          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 client-secret reconciler (platform/keycloak/client-secret-reconciler.yaml) ---
        # WHY THESE EXIST: on 2026-09-06 every OIDC login on prod failed because the realm import
        # had stored the LITERAL `(env:...)` placeholder as all 12 client secrets — and every
        # signal the cluster offered was GREEN (the import Job succeeded, the CR read Done=True,
        # KeycloakDown/KeycloakDatabaseDown were quiet, the conformance test that asserts
        # Done=True passed). The only observable was a human failing to log in. The CronJob is
        # the healer; these two rules make its SILENCE observable, so the class cannot sit
        # undetected again. They are the runtime counterpart of the L2 audit test.
        #
        # UNVERIFIED-ON-CLUSTER at authoring time: no CronJob existed on either cluster yet, so
        # these series had no samples to check against. `kube_job_status_failed` /
        # `kube_job_status_succeeded` and the `job_name` label WERE confirmed present (the realm
        # import Job exports them); the reconciler's own series appear with its first run.
        # Confirm with: kube_job_status_succeeded{namespace="keycloak",
        # job_name=~"keycloak-client-secret-reconciler-.*"}
        - alert: KeycloakClientSecretReconcilerFailing
          # A reconciler run failed. Either it found drift it could not repair, or it could not
          # reach the admin API. Fires alongside KeycloakDown during an IdP outage — that is
          # deliberate (the reconciler genuinely is not running), so treat KeycloakDown as the
          # cause when both are lit. Self-clears when the failed Jobs age out (TTL 1h).
          expr: |
            max(kube_job_status_failed{namespace="keycloak", job_name=~"keycloak-client-secret-reconciler-.*"}) > 0
          for: 15m
          labels:
            severity: warning
          annotations:
            summary: "Keycloak client-secret reconciler failing"
            description: >-
              A keycloak-client-secret-reconciler Job has been failing for 15m — an OIDC client
              secret may differ from git (unresolved import placeholder, or an unrepairable
              drift) and SSO logins for that client will fail. Read the Job log: it names the
              client and never prints a secret.
            runbook_url: "https://${BASE_DOMAIN}/runbooks/keycloak-client-secrets"
        - alert: KeycloakClientSecretReconcilerStale
          # No SUCCESSFUL run in scope. Catches the failure modes the rule above cannot see: the
          # CronJob suspended, never applied by Flux, or unable to schedule a pod at all — i.e.
          # the healer being quietly absent, which is exactly the "looks applied and isn't"
          # failure this whole change exists to end.
          expr: |
            absent(kube_job_status_succeeded{namespace="keycloak", job_name=~"keycloak-client-secret-reconciler-.*"} == 1)
          for: 2h
          labels:
            severity: warning
          annotations:
            summary: "Keycloak client-secret reconciler has not succeeded"
            description: >-
              No successful keycloak-client-secret-reconciler run in 2h (schedule is every 15m).
              The CronJob may be suspended, unapplied, or unable to schedule — client-secret
              drift would go uncorrected and unnoticed (docs/15).
            runbook_url: "https://${BASE_DOMAIN}/runbooks/keycloak-client-secrets"

# =====================================================================================
# 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"