# Bookstore Platform v2 — Part 13 ch.03: the root ApplicationSet that fans
# the platform-base stack across all three regional clusters via the Cluster
# generator. Run from the management cluster (us-east, by convention; the
# Argo CD instance there has all three clusters registered via
# `argocd cluster add`).
#
# How the Cluster generator works (Part 11 ch.06 deepened): it enumerates
# every Cluster Secret in argocd's namespace and, for each matching the
# label selector, instantiates a templated Application. The template below
# selects clusters labelled `bookstore-platform.example.com/region` (set by
# `argocd cluster add --label`); each generated Application points at the
# matching region overlay.
#
# Generated Application names: `platform-base-<REGION>`. Server URLs come
# from the cluster Secret automatically — never hard-coded.
#
# !!! CRD-INTRINSIC DRY-RUN
#   `ApplicationSet` is `argoproj.io/v1alpha1` — an Argo CD CRD. WITHOUT
#   Argo CD installed (cross-ref Part 07 ch.04 install path), a client
#   dry-run prints:
#     no matches for kind "ApplicationSet" in version "argoproj.io/v1alpha1"
#   EXPECTED. After Argo CD is installed, this applies; the App-of-Apps + the
#   per-cluster Applications are generated within seconds.
#
# Apply (after Argo CD installed + clusters added):
#   argocd cluster add kind-bookstore-platform-us-east \
#     --label bookstore-platform.example.com/region=us-east
#   argocd cluster add kind-bookstore-platform-eu-west \
#     --label bookstore-platform.example.com/region=eu-west
#   argocd cluster add kind-bookstore-platform-ap-southeast \
#     --label bookstore-platform.example.com/region=ap-southeast
#   kubectl apply -f examples/bookstore-platform/argocd/applicationset-platform.yaml
#   kubectl get applications -n argocd | grep platform-base
apiVersion: argoproj.io/v1alpha1
kind: ApplicationSet
metadata:
  name: platform-base
  namespace: argocd
  labels:
    app.kubernetes.io/part-of: bookstore-platform
spec:
  generators:
    - clusters:
        selector:
          # Match only clusters that carry the platform region label —
          # excludes the in-cluster (management) Argo CD destination and
          # any cluster Secret added without the platform region label.
          # The previous matchLabels of `argocd.argoproj.io/secret-type:
          # cluster` matched every registered cluster (too broad — it
          # would have fanned the platform-base out to any Argo CD-
          # registered cluster, regardless of whether it belongs to this
          # platform).
          matchExpressions:
            - key: bookstore-platform.example.com/region
              operator: Exists
        values:
          # surface the region label into the template
          region: "{{ index .metadata.labels \"bookstore-platform.example.com/region\" }}"
  template:
    metadata:
      name: "platform-base-{{ .values.region }}"
      labels:
        app.kubernetes.io/part-of: bookstore-platform
        bookstore-platform.example.com/region: "{{ .values.region }}"
    spec:
      project: default
      source:
        # PLACEHOLDER: replace `https://github.com/<ORG>/<REPO>` with the real
        # Git remote URL of the platform repo. The path tracks the region
        # overlay; the chart-less Kustomize path matches `examples/bookstore-
        # platform/kustomize/regions/<REGION>/`.
        repoURL: "https://github.com/<ORG>/<REPO>"
        targetRevision: main
        path: "full-guide/examples/bookstore-platform/kustomize/regions/{{ .values.region }}"
      destination:
        # The Cluster generator filled in `name` automatically from the
        # registered cluster Secret — no hard-coded URL.
        name: "{{ .name }}"
        # platform-base creates the bookstore-platform-* namespaces itself;
        # Argo CD's syncPolicy CreateNamespace is OFF for that reason.
      syncPolicy:
        automated:
          prune: true
          selfHeal: true
        syncOptions:
          - PrunePropagationPolicy=foreground
          - ApplyOutOfSyncOnly=true
        retry:
          limit: 5
          backoff:
            duration: 30s
            factor: 2
            maxDuration: 5m