# =============================================================================
# L2 BEHAVIORAL — split-horizon INTERNAL resolution  (R-DNS-01 / R-DNS-03)   [RUNNABLE]
# Catalog: docs/14 "DNS/exposure (R-DNS-*)"
# Spec:    docs/09 "Split-horizon resolution (R-DNS-03)" — internal clients resolve
#          <svc>.home.keithjackson.dev to the INTERNAL Gateway VIP, not the public hairpin.
# Impl:    platform/coredns/coredns-custom.yaml (k3s CoreDNS `import *.server`; template plugin
#          answers the whole home.keithjackson.dev zone with ${GATEWAY_VIP}).
#
# GIVEN the split-horizon coredns-custom ConfigMap is reconciled into k3s CoreDNS,
# WHEN  an in-cluster pod resolves a platform hostname over its PUBLIC name
#       (keycloak.home.keithjackson.dev) using the default cluster resolver (CoreDNS 10.43.0.10),
# THEN  the answer is the in-cluster Gateway VIP (the L2-announced LB range 10.73.0.24x) — NOT a
#       public/off-cluster IP. This is what lets pod->public-hostname traffic hairpin through the
#       Gateway with the correct SNI (*.home.keithjackson.dev) so the wildcard cert validates
#       (R-DNS-01 "services reachable at <svc>.home..."; R-DNS-03 split-horizon).
#
# Complements dns-exposure (R-DNS-02, the EXTERNAL/public-record side). Together they cover the
# split-horizon pair: external answer = public record (R-DNS-02); internal answer = Gateway VIP
# (R-DNS-01/03).
#
# CLEANUP: chainsaw deletes the per-test namespace (Job included) at teardown. Read-only otherwise.
# chainsaw v0.2.12: Job + status assert; no test-level finally.
# =============================================================================
apiVersion: chainsaw.kyverno.io/v1alpha1
kind: Test
metadata:
  name: dns-internal-resolution
  labels:
    conformance.home.k3s/R-DNS-01: "true"
    conformance.home.k3s/R-DNS-03: "true"
  annotations:
    conformance.home.k3s/requirements: "R-DNS-01,R-DNS-03"
    conformance.home.k3s/layer: "L2"
    conformance.home.k3s/safety-critical: "false"
    conformance.home.k3s/executable: "true"
    conformance.home.k3s/intent: >-
      An in-cluster pod resolving keycloak.home.keithjackson.dev via cluster DNS gets the internal
      Gateway VIP (10.73.0.24x), not the public hairpin — split-horizon in-cluster resolution.
spec:
  timeouts:
    apply: 60s
    assert: 2m
    exec: 2m
  steps:
    - name: then-cluster-dns-answers-with-the-internal-gateway-vip
      try:
        - apply:
            resource:
              apiVersion: batch/v1
              kind: Job
              metadata:
                name: dns-internal-probe
              spec:
                backoffLimit: 2
                activeDeadlineSeconds: 100
                template:
                  spec:
                    restartPolicy: Never
                    containers:
                      - name: probe
                        image: busybox:1.36.1
                        command:
                          - sh
                          - -c
                          - |
                            set -u
                            host="keycloak.home.keithjackson.dev"
                            # Resolve via the DEFAULT cluster resolver (CoreDNS, /etc/resolv.conf ->
                            # 10.43.0.10). Split-horizon must answer with the in-cluster Gateway VIP
                            # (L2 pool 10.73.0.24x), proving pods hairpin through the Gateway.
                            out="$(nslookup "$host" 2>/dev/null)"
                            echo "$out"
                            ip="$(echo "$out" | awk '/^Address: /{print $2}' | grep -E '^10\.73\.0\.24[0-9]$' | head -1)"
                            if [ -n "$ip" ]; then
                              echo "INTERNAL_RESOLUTION_OK $host -> $ip (in-cluster Gateway VIP)"
                              exit 0
                            fi
                            echo "FAIL: $host did not resolve to the in-cluster Gateway VIP (10.73.0.24x);"
                            echo "      split-horizon coredns-custom not in effect (got a public/off-cluster answer)."
                            exit 1
        - assert:
            resource:
              apiVersion: batch/v1
              kind: Job
              metadata:
                name: dns-internal-probe
              status:
                succeeded: 1