postgres controllers metrics

[limak9182]

Description

Adds comprehensive Prometheus metrics for the PostgreSQL controllers using a hexagonal
(ports & adapters) pattern — the domain code depends only on a Recorder interface, never
on Prometheus directly.

New package: pkg/postgresql/metrics/

• ports.go — Recorder interface (the port). Core service packages import only this.
• prometheus.go — PrometheusRecorder adapter: 6 metric families with splunk_operator_postgres_ prefix, registered against the controller-runtime metrics registry.
• noop.go — NoopRecorder for unit tests.
• collector.go — FleetCollector that recomputes fleet-state gauges from the informer cache after each reconcile.

Three-layer metrics collection:

Layer	What it covers	How
Controller-runtime (free)	Reconcile count, duration, errors	Automatic — controller_runtime_reconcile_total, _time_seconds, _errors_total
Fleet collector	Clusters/databases by phase, managed users, poolers	FleetCollector lists CRs from cache and sets gauges
Status-driven	Business-logic transitions	IncStatusTransition() called automatically inside persistStatus/setStatus — zero manual metric calls in service code

Custom metrics (6 families):

Metric	Type	Description
status_transitions_total	Counter	Status condition transitions by controller, condition, status, reason
clusters	Gauge	Clusters by phase and pooler status
databases	Gauge	Databases by phase
managed_users	Gauge	User counts by state (desired/reconciled/pending/failed)
poolers	Gauge	PgBouncer poolers by type and state
pooler_instances	Gauge	Pooler instance count

Design decisions:

• No custom reconcile-level metrics — controller-runtime provides these out of the box
• Status-driven metric emission — IncStatusTransition is called inside persistStatus/setStatus, so every condition write is automatically captured with no explicit calls scattered through service code
• Low-cardinality labels only (controller, condition, status, reason, phase) — no per-resource name/namespace labels
• Hexagonal port enables testability (NoopRecorder) and adapter swappability
• Existing pkg/splunk/client/metrics/ is untouched

Key Changes

• pkg/postgresql/metrics/ — new package: port interface, Prometheus adapter, noop adapter, fleet collector
• pkg/postgresql/cluster/core/cluster.go — setStatus, syncPoolerStatus, syncStatus now accept Recorder and emit IncStatusTransition automatically
• pkg/postgresql/database/core/database.go — persistStatus now accepts Recorder and emits IncStatusTransition automatically. Also adds 2 missing updateStatus calls on error paths (role patch failure, database reconcile failure)
• pkg/postgresql/{cluster,database}/core/types.go — Metrics pgmetrics.Recorder field added to ReconcileContext
• internal/controller/postgres{cluster,database}_controller.go — inject Metrics into ReconcileContext, call fleet collector after each reconcile
• cmd/main.go — create PrometheusRecorder, register with controller-runtime metrics registry, pass to controllers

Testing and Verification

Setting up Grafana + Prometheus on KIND

1. Install the monitoring stack

kubectl create namespace monitoring

# Add helm repos
helm repo add prometheus-community https://prometheus-community.github.io/helm-charts
helm repo add grafana https://grafana.github.io/helm-charts
helm repo update

# Install kube-prometheus-stack
helm install kube-prometheus prometheus-community/kube-prometheus-stack \
  --namespace monitoring \
  --set grafana.adminPassword=admin \
  --set alertmanager.enabled=false \
  --set kubeStateMetrics.enabled=false \
  --set nodeExporter.enabled=false

2. Grant Prometheus access to scrape the operator metrics

  kubectl apply -f - <<EOF
  apiVersion: rbac.authorization.k8s.io/v1
  kind: ClusterRoleBinding
  metadata:
    name: prometheus-splunk-operator-metrics
  roleRef:
    apiGroup: rbac.authorization.k8s.io
    kind: ClusterRole
    name: splunk-operator-metrics-reader
  subjects:
  - kind: ServiceAccount
    name: prometheus
    namespace: monitoring
  EOF

3. Create a ServiceMonitor

  kubectl apply -f - <<EOF
  apiVersion: monitoring.coreos.com/v1
  kind: ServiceMonitor
  metadata:
    name: splunk-operator-postgres
    namespace: monitoring
    labels:
      release: kube-prometheus
  spec:
    namespaceSelector:
      matchNames:
      - splunk-operator
    selector:
      matchLabels:
        control-plane: controller-manager
    endpoints:
    - port: metric
      path: /metrics
      interval: 5s
      bearerTokenFile: /var/run/secrets/kubernetes.io/serviceaccount/token
  EOF

4. Access Grafana

kubectl port-forward svc/kube-prometheus-grafana -n monitoring 3000:80

Open http://localhost:3000 — login: admin / admin

The Prometheus datasource is auto-configured. Query any metric with the splunk_operator_postgres_ prefix.

5. Example PromQL queries

  # Status transitions by controller and reason (error signals)
  sum by (controller, reason) (rate(splunk_operator_postgres_status_transitions_total{status="False"}[5m]))

  # Databases by phase
  splunk_operator_postgres_databases

  # Clusters by phase
  splunk_operator_postgres_clusters

  # Managed users overview
  splunk_operator_postgres_managed_users

  # Reconcile rate by controller (controller-runtime automatic)
  rate(controller_runtime_reconcile_total{controller=~"postgres.*"}[5m])

  # p99 latency per controller (controller-runtime automatic)
  histogram_quantile(0.99, sum by (controller, le) (rate(controller_runtime_reconcile_time_seconds_bucket{controller=~"postgres.*"}[5m])))

Related Issues

Jira tickets, GitHub issues, Support tickets...

PR Checklist

• Code changes adhere to the project's coding standards.
• Relevant unit and integration tests are included.
• Documentation has been updated accordingly.
• All tests pass locally.
• The PR description follows the project's guidelines.

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