feat(kanidm): vault-managed replication certs with auto-restart (#176)

- Store per-pod replication certs in Vault (kv/kubernetes/namespace/kanidm/default/repl-certs)
- VaultAuth + VaultStaticSecret sync certs to kanidm-repl-certs Secret
- busybox config-init init container injects peer certs from Secret into server.toml at startup
- Remove hardcoded partner_cert entries from per-pod server.toml templates
- Add automatic_refresh = true to all replication configs
- Add reloader.stakater.com/auto annotation to trigger rolling restart on ConfigMap/Secret changes
- Document domain UUID mismatch resolution and cert rotation in README

Reviewed-on: #176

apps/base/kanidm/README.md

@@ -1,32 +1,51 @@
 # kanidm
 
-Single-replica kanidm identity server deployment.
+Three-replica kanidm identity server with Vault-managed replication certificates.
+
+## Architecture
+
+- Per-pod `server-N.toml` in `resources/` — each has its own replication origin hardcoded
+- `config-init` busybox init container copies the right config and injects peer certs from the
+  vault-synced `kanidm-repl-certs` Secret at pod startup
+- `reloader.stakater.com/auto: "true"` triggers a rolling restart when the ConfigMap or Secret changes
+- Vault path: `kv/kubernetes/namespace/kanidm/default/repl-certs`
+  - Keys: `kanidm-0`, `kanidm-1`, `kanidm-2` — each holds that pod's replication certificate
 
 ## Initial setup
 
-After the pod starts for the first time, generate the admin and idm_admin credentials:
+After the first pod starts, generate the admin credentials:
 
 ```bash
-kubectl exec -n kanidm kanidm-0 -- /sbin/kanidmd recover-account admin
-kubectl exec -n kanidm kanidm-0 -- /sbin/kanidmd recover-account idm_admin
+kubectl exec -n kanidm kanidm-0 -- /sbin/kanidmd recover-account -c /config/server.toml admin
+kubectl exec -n kanidm kanidm-0 -- /sbin/kanidmd recover-account -c /config/server.toml idm_admin
 ```
 
-## Adding replication
+## Replication certificate rotation
 
-If replication is needed in the future:
-
-1. Scale the StatefulSet to 3 replicas and add `podAntiAffinity` to spread across nodes.
-2. Add a `[replication]` section to `configmap.yaml` per pod (origin is pod-specific:
-   `repl://kanidm-N.kanidm-headless.kanidm.svc.cluster.local:8444`).
-3. Add the replication port (8444) back to the StatefulSet container ports and headless service.
-4. Restore `rbac.yaml` for the cert-publisher sidecar, or exchange certificates manually:
+When certs need to be renewed, update vault and reloader will roll the StatefulSet:
 
 ```bash
-# On each pod, get its replication certificate
-kubectl exec -n kanidm kanidm-0 -- /sbin/kanidmd renew-replication-certificate
+# Get new cert from a pod
+kubectl exec -it -n kanidm kanidm-N -- /sbin/kanidmd renew-replication-certificate -c /config/server.toml
 
-# Add each peer's certificate to the other pods' configs under:
-# [replication."repl://<peer-fqdn>:8444"]
-# type = "mutual-pull"
-# partner_cert = "<cert>"
+# Write updated cert to vault (reloader triggers restart automatically)
+vault kv patch kv/kubernetes/namespace/kanidm/default/repl-certs "kanidm-N=<cert>"
+```
+
+## Resolving domain UUID mismatch
+
+If pods initialized independently (each with a different domain UUID), replication will fail with
+`Consumer Domain UUID does not match`. Fix by resetting kanidm-1 and kanidm-2 to sync from
+kanidm-0 (the authoritative node):
+
+```bash
+# Scale down to avoid split-brain during reset
+kubectl scale statefulset -n kanidm kanidm --replicas=1
+
+# Delete the stale PVCs for the replica pods
+kubectl delete pvc -n kanidm data-kanidm-1 data-kanidm-2
+
+# Scale back up — replicas start with empty DBs and automatic_refresh=true
+# will trigger a full sync from kanidm-0 once TLS peer certs are verified
+kubectl scale statefulset -n kanidm kanidm --replicas=3
 ```