feat: add PuppetDB read-only database user and pooler (#69)

PuppetDB requires a separate read-only database user for its read pool.
Without it, it refuses to use the write user for read queries and all
/pdb/query/v4 calls fail with a 500.

- Add puppetdb_read role via CNPG managed.roles with password sourced
  from a new postgres-read-credentials Vault secret
- Grant CONNECT, USAGE, SELECT and default privileges to puppetdb_read
  via postInitApplicationSQL (must also be run manually on existing cluster)
- Add puppet-postgres-pooler-ro Pooler (type: ro) routing to replicas
- Add puppetdb-read-database-conf ConfigMap with read-database.conf
  mounted into /etc/puppetlabs/puppetdb/conf.d/ in the PuppetDB deployment
- Wire OPENVOXDB_READ_POSTGRES_* env vars from the new secret

💘 Generated with Crush

Assisted-by: Claude Sonnet 4.6 via Crush <crush@charm.land>

Reviewed-on: #69

apps/base/puppet/cnpg_cluster.yaml

@@ -19,6 +19,24 @@ spec:
       postInitApplicationSQL:
         - CREATE EXTENSION IF NOT EXISTS pg_trgm;
         - CREATE EXTENSION IF NOT EXISTS pgcrypto;
+        - GRANT CONNECT ON DATABASE puppetdb TO puppetdb_read;
+        - GRANT USAGE ON SCHEMA public TO puppetdb_read;
+        - GRANT SELECT ON ALL TABLES IN SCHEMA public TO puppetdb_read;
+        - ALTER DEFAULT PRIVILEGES IN SCHEMA public GRANT SELECT ON TABLES TO puppetdb_read;
+  managed:
+    roles:
+      - name: puppetdb_read
+        ensure: present
+        comment: PuppetDB read-only database user
+        login: true
+        superuser: false
+        createdb: false
+        createrole: false
+        inherit: true
+        replication: false
+        connectionLimit: -1
+        passwordSecret:
+          name: postgres-read-credentials
   enablePDB: true
   enableSuperuserAccess: false
   failoverDelay: 0

apps/base/puppet/cnpg_pooler.yaml

@@ -31,3 +31,36 @@ spec:
               topologyKey: kubernetes.io/hostname
       containers: []
   type: rw
+---
+apiVersion: postgresql.cnpg.io/v1
+kind: Pooler
+metadata:
+  name: puppet-postgres-pooler-ro
+  namespace: puppet
+spec:
+  cluster:
+    name: puppet-postgres
+  instances: 2
+  pgbouncer:
+    parameters:
+      default_pool_size: "100"
+      max_client_conn: "400"
+    paused: false
+    poolMode: session
+  template:
+    metadata:
+      labels:
+        app: pooler-ro
+    spec:
+      affinity:
+        podAntiAffinity:
+          requiredDuringSchedulingIgnoredDuringExecution:
+            - labelSelector:
+                matchExpressions:
+                  - key: app
+                    operator: In
+                    values:
+                      - pooler-ro
+              topologyKey: kubernetes.io/hostname
+      containers: []
+  type: ro

apps/base/puppet/configmap_puppetdb-config.yaml

@@ -17,4 +17,7 @@ data:
   OPENVOXDB_POSTGRES_HOSTNAME: "puppet-postgres-pooler"
   OPENVOXDB_POSTGRES_DATABASE: "puppetdb"
   OPENVOXDB_POSTGRES_PORT: "5432"
+  OPENVOXDB_READ_POSTGRES_HOSTNAME: "puppet-postgres-pooler-ro"
+  OPENVOXDB_READ_POSTGRES_DATABASE: "puppetdb"
+  OPENVOXDB_READ_POSTGRES_PORT: "5432"
   PUPPETDB_JAVA_ARGS: ""

apps/base/puppet/configmap_puppetdb-read-database.yaml

@@ -0,0 +1,18 @@
+---
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  labels:
+    app.kubernetes.io/component: puppetdb
+    app.kubernetes.io/instance: puppetserver
+    app.kubernetes.io/name: puppetserver
+    app.kubernetes.io/version: 8.8.0
+  name: puppetdb-read-database-conf
+  namespace: puppet
+data:
+  read-database.conf: |
+    read-database: {
+      subname: "//"${OPENVOXDB_READ_POSTGRES_HOSTNAME}":"${OPENVOXDB_READ_POSTGRES_PORT}"/"${OPENVOXDB_READ_POSTGRES_DATABASE}
+      username: ${OPENVOXDB_READ_POSTGRES_USER}
+      password: ${OPENVOXDB_READ_POSTGRES_PASSWORD}
+    }

apps/base/puppet/deployment_puppetdb.yaml

@@ -59,6 +59,16 @@ spec:
                 secretKeyRef:
                   key: username
                   name: postgres-credentials
+            - name: OPENVOXDB_READ_POSTGRES_PASSWORD
+              valueFrom:
+                secretKeyRef:
+                  key: password
+                  name: postgres-read-credentials
+            - name: OPENVOXDB_READ_POSTGRES_USER
+              valueFrom:
+                secretKeyRef:
+                  key: username
+                  name: postgres-read-credentials
           securityContext:
             allowPrivilegeEscalation: false
             capabilities:
@@ -78,6 +88,9 @@ spec:
           volumeMounts:
             - mountPath: /opt/puppetlabs/server/data/puppetdb
               name: puppetdb-storage
+            - mountPath: /etc/puppetlabs/puppetdb/conf.d/read-database.conf
+              name: puppetdb-read-database-conf
+              subPath: read-database.conf
       initContainers:
         - name: create-log-dir
           image: docker.io/busybox:1.37
@@ -154,3 +167,6 @@ spec:
         - name: puppetdb-storage
           persistentVolumeClaim:
             claimName: puppetserver-puppetdb-claim
+        - name: puppetdb-read-database-conf
+          configMap:
+            name: puppetdb-read-database-conf

apps/base/puppet/kustomization.yaml

@@ -12,6 +12,7 @@ resources:
   - vaultstaticsecret.yaml
   - configmap_puppetboard-config.yaml
   - configmap_puppetdb-config.yaml
+  - configmap_puppetdb-read-database.yaml
   - configmap_puppetserver-compiler-config.yaml
   - configmap_puppetserver-init-config.yaml
   - configmap_puppetserver-init-masters-config.yaml

apps/base/puppet/vaultstaticsecret.yaml

@@ -35,6 +35,23 @@ spec:
 ---
 apiVersion: secrets.hashicorp.com/v1beta1
 kind: VaultStaticSecret
+metadata:
+  name: postgres-read-credentials
+  namespace: puppet
+spec:
+  destination:
+    create: true
+    name: postgres-read-credentials
+    overwrite: true
+  hmacSecretData: true
+  mount: kv
+  path: kubernetes/namespace/puppet/default/postgres-read-credentials
+  refreshAfter: 5m
+  type: kv-v2
+  vaultAuthRef: default
+---
+apiVersion: secrets.hashicorp.com/v1beta1
+kind: VaultStaticSecret
 metadata:
   name: eyaml-keys
   namespace: puppet