Add Let's Encrypt DNS-01 clouddns ClusterIssuers

unkin.net public DNS is delegated to Google Cloud DNS, so publicly-trusted
wildcard certs need an ACME issuer using cert-manager's clouddns DNS-01
solver. The existing vault-issuer (internal PKI) is unchanged.

- Add ClusterIssuers letsencrypt (prod) and letsencrypt-staging, both using
  a dns01 clouddns solver with a GCP service-account key.
- Sync that key from Vault KV into Secret cert-manager-clouddns via a
  VaultStaticSecret + VaultAuth (role cert_manager_clouddns) and a dedicated
  cert-manager-clouddns service account.
- Wire the new files into the base kustomization.
- Whitelist cert-manager.io ClusterIssuer in the platform AppProject.

The clouddns project and the KV secret value are set out-of-band.

Claude-Session: https://claude.ai/code/session_01JUoARVdmhxKQHyyyp1pxeT

apps/base/cert-manager/clusterissuer_letsencrypt-staging.yaml

@@ -0,0 +1,19 @@
+---
+apiVersion: cert-manager.io/v1
+kind: ClusterIssuer
+metadata:
+  name: letsencrypt-staging
+spec:
+  acme:
+    server: https://acme-staging-v02.api.letsencrypt.org/directory
+    email: admin@unkin.net
+    privateKeySecretRef:
+      name: letsencrypt-staging-account-key
+    solvers:
+      - dns01:
+          # project must match the GCP project hosting the unkin.net Cloud DNS zone
+          cloudDNS:
+            project: REPLACE-WITH-GCP-PROJECT
+            serviceAccountSecretRef:
+              name: cert-manager-clouddns
+              key: key.json

apps/base/cert-manager/clusterissuer_letsencrypt.yaml

@@ -0,0 +1,19 @@
+---
+apiVersion: cert-manager.io/v1
+kind: ClusterIssuer
+metadata:
+  name: letsencrypt
+spec:
+  acme:
+    server: https://acme-v02.api.letsencrypt.org/directory
+    email: admin@unkin.net
+    privateKeySecretRef:
+      name: letsencrypt-account-key
+    solvers:
+      - dns01:
+          # project must match the GCP project hosting the unkin.net Cloud DNS zone
+          cloudDNS:
+            project: REPLACE-WITH-GCP-PROJECT
+            serviceAccountSecretRef:
+              name: cert-manager-clouddns
+              key: key.json

apps/base/cert-manager/kustomization.yaml

@@ -5,6 +5,11 @@ kind: Kustomization
 resources:
   - namespace.yaml
   - serviceaccount.yaml
+  - serviceaccount_cert-manager-clouddns.yaml
   - clusterrole.yaml
   - clusterrolebinding.yaml
   - vmservicescrape.yaml
+  - vaultauth.yaml
+  - vaultstaticsecret_clouddns.yaml
+  - clusterissuer_letsencrypt.yaml
+  - clusterissuer_letsencrypt-staging.yaml

apps/base/cert-manager/serviceaccount_cert-manager-clouddns.yaml

@@ -0,0 +1,11 @@
+---
+apiVersion: v1
+kind: ServiceAccount
+metadata:
+  name: cert-manager-clouddns
+  namespace: cert-manager
+  labels:
+    app.kubernetes.io/name: cert-manager-config
+    app.kubernetes.io/instance: cert-manager-config
+    app.kubernetes.io/component: clouddns-solver
+automountServiceAccountToken: true

apps/base/cert-manager/vaultauth.yaml

@@ -0,0 +1,18 @@
+---
+apiVersion: secrets.hashicorp.com/v1beta1
+kind: VaultAuth
+metadata:
+  name: default
+  namespace: cert-manager
+spec:
+  method: kubernetes
+  mount: k8s/au/syd1
+  vaultConnectionRef: vso-system/default
+  allowedNamespaces:
+    - cert-manager
+  kubernetes:
+    role: cert_manager_clouddns
+    serviceAccount: cert-manager-clouddns
+    audiences:
+      - vault
+    tokenExpirationSeconds: 600

apps/base/cert-manager/vaultstaticsecret_clouddns.yaml

@@ -0,0 +1,15 @@
+---
+apiVersion: secrets.hashicorp.com/v1beta1
+kind: VaultStaticSecret
+metadata:
+  name: clouddns
+  namespace: cert-manager
+spec:
+  vaultAuthRef: default
+  mount: kv
+  type: kv-v2
+  path: service/kubernetes/au/syd1/cert-manager/clouddns
+  refreshAfter: 5m
+  destination:
+    name: cert-manager-clouddns
+    create: true

argocd/projects/platform.yaml

@@ -84,6 +84,8 @@ spec:
       kind: Certificate
     - group: 'cert-manager.io'
       kind: Issuer
+    - group: 'cert-manager.io'
+      kind: ClusterIssuer
     - group: 'gateway.networking.k8s.io'
       kind: GatewayClass
     - group: 'networking.k8s.io'