# Bookstore — Part 06 ch.01 "Observability: metrics": scrape config as data.
#
# Two ServiceMonitor objects tell the Prometheus Operator WHICH Services to
# scrape and HOW — without editing prometheus.yml. The Operator watches
# ServiceMonitors, turns each into a scrape job, and reloads Prometheus. This
# is the "monitoring config is just Kubernetes objects" model (ch.01).
#
#   • catalog        — selects the `catalog` Service (40-services.yaml),
#     scrapes its `http` port at /metrics. catalog exposes
#     http_requests_total{handler,code} + http_request_duration_seconds (a
#     histogram, DefBuckets) — app/catalog/main.go. orders is identical and
#     can be added the same way (left out only to keep the example tight; the
#     chapter notes it).
#   • payments-worker — selects the HEADLESS `payments-worker` Service
#     (40-services.yaml), scrapes its `metrics` port. The worker has no
#     inbound API but exposes payments_processed_total + Go runtime metrics
#     (app/payments-worker/main.go); the headless Service exists purely to
#     give the Operator scrape endpoints (one per Ready Pod).
#
# !!! CRD-BACKED — intrinsic dry-run behaviour (exactly like 18-/51-/70-) !!!
# `ServiceMonitor` is a Prometheus Operator CRD (apiGroup
# monitoring.coreos.com/v1), NOT a built-in kind. On a cluster WITHOUT the
# Operator installed, `kubectl apply --dry-run=client -f` (or a whole-dir
# client dry-run) prints:
#     error: resource mapping not found for ... kind "ServiceMonitor" in
#     version "monitoring.coreos.com/v1" ... ensure CRDs are installed first
#     (no matches for kind "ServiceMonitor")
# That is EXPECTED and not a manifest defect — identical to the Gateway API
# (51-), VolumeSnapshot (18-) and Kyverno ClusterPolicy (70-) situations. A
# whole-dir client dry-run that has not installed the Operator prints this for
# THIS file (and 81-/83-) only and continues; every built-in object still
# validates. Schema below verified against the Prometheus Operator
# monitoring.coreos.com/v1 ServiceMonitor API.
#
# !!! THE `release` LABEL MATTERS !!!  kube-prometheus-stack's bundled
# Prometheus has `serviceMonitorSelector: matchLabels: {release: <helm
# release name>}` by default. A ServiceMonitor WITHOUT that label is silently
# ignored (valid object, never scraped — the #1 "my ServiceMonitor does
# nothing" cause). The hands-on installs the chart as release
# `kube-prometheus-stack`, so that is the label value here. If you used a
# different release name, change it (or set the chart value
# prometheus.prometheusSpec.serviceMonitorSelectorNilUsesHelmValues=false).
#
# Requires (to actually apply, not just read):
#   - kube-prometheus-stack installed (Prometheus Operator + CRDs) in the
#     `monitoring` namespace (Part 06 ch.01 hands-on)
#   - 40-services.yaml applied (the catalog + payments-worker Services exist)
#   - 10-/19- applied (so those Services have Endpoints)
#   - 60-networkpolicy.yaml rule 10 (monitoring -> :8080) so scrapes are not
#     blocked once a policy-enforcing CNI is in play
# Apply (Operator-equipped cluster only):
#   kubectl apply -f examples/bookstore/raw-manifests/80-servicemonitor.yaml
#   kubectl get servicemonitor -n bookstore
#   # then in the Prometheus UI: Status -> Targets -> bookstore/catalog UP
apiVersion: monitoring.coreos.com/v1
kind: ServiceMonitor
metadata:
  name: catalog
  namespace: bookstore
  labels:
    app: catalog
    app.kubernetes.io/part-of: bookstore
    release: kube-prometheus-stack   # MUST match the Prometheus serviceMonitorSelector
spec:
  # Select the catalog Service (40-services.yaml) by its labels. The Operator
  # then scrapes that Service's Endpoints (the catalog Pods).
  selector:
    matchLabels:
      app: catalog
  namespaceSelector:
    matchNames: ["bookstore"]
  endpoints:
    - port: http                     # the catalog Service's named port (-> 8080)
      path: /metrics                 # promhttp.Handler() route (app/catalog/main.go)
      interval: 15s
      scheme: http
---
apiVersion: monitoring.coreos.com/v1
kind: ServiceMonitor
metadata:
  name: payments-worker
  namespace: bookstore
  labels:
    app: payments-worker
    app.kubernetes.io/part-of: bookstore
    release: kube-prometheus-stack
spec:
  selector:
    matchLabels:
      app: payments-worker
  namespaceSelector:
    matchNames: ["bookstore"]
  endpoints:
    - port: metrics                  # the headless Service's named port (-> 8080)
      path: /metrics
      interval: 15s
      scheme: http