GitLab cross-site replication Phase 2a (corrected): ignoreDifferences approach

The CONFIG_TEMPLATE_DIRECTORY redirect from the previous commit doesn't
work - confirmed live that extraVolumes is a dead values key for the
Praefect subchart specifically (its statefulset.yaml never calls the
gitlab.extraVolumes helper in its volumes: list, only volumeMounts
calls the corresponding helper - a real chart limitation, not a config
mistake). A dangling volumeMount with no matching volume would have
failed to schedule.

Real fix: ignoreDifferences on ConfigMap gitlab-praefect's data field
(argocd-apps/apps/gitlab.yaml) lets Helm create the object normally
while ArgoCD stops reconciling its content afterward - the actual
config gets kubectl-patched onto the live object directly.
praefect-ha-configmap.yaml is now a git-tracked reference/documentation
copy (deployed under its own harmless name) rather than something
Helm/ArgoCD wires in on its own.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

apps/gitlab/values.yaml

@@ -308,30 +308,29 @@ gitlab:
     # this one, so gitalyReplicas: 3 up there always won regardless of
     # what this said. See global.praefect.virtualStorages above for the
     # real config.)
-
-    # GitLab cross-site replication Phase 2a (see
-    # /home/scooby/.claude/plans/jiggly-snacking-iverson.md) - redirects
-    # Praefect's config template source so a hand-written config.toml.tpl
-    # (praefect-ha-configmap.yaml) can add a VPS-hosted Gitaly node the
-    # chart itself has no mechanism to register. The chart's own
-    # gitlab-praefect ConfigMap is already mounted at
-    # /etc/gitaly/templates (which CONFIG_TEMPLATE_DIRECTORY points at by
-    # default) - can't add a second volume at that same path/name
-    # (Kubernetes rejects duplicate volume names), so this mounts the
-    # override at a different path and points CONFIG_TEMPLATE_DIRECTORY
-    # there instead. Duplicate env var names in a container's env: list
-    # resolve last-wins (documented Kubernetes behavior) - this entry
-    # renders after the chart's own, so it's the one that takes effect.
-    extraEnv:
-      CONFIG_TEMPLATE_DIRECTORY: /etc/gitaly/templates-ha
-    extraVolumes:
-      - name: praefect-ha-config
-        configMap:
-          name: praefect-ha-config
-    extraVolumeMounts:
-      - name: praefect-ha-config
-        mountPath: /etc/gitaly/templates-ha
-        readOnly: true
+    #
+    # GitLab cross-site replication (see
+    # /home/scooby/.claude/plans/jiggly-snacking-iverson.md): tried a
+    # values-only CONFIG_TEMPLATE_DIRECTORY redirect (extraEnv +
+    # extraVolumes/extraVolumeMounts) to add a VPS-hosted Gitaly node the
+    # chart has no mechanism to register - confirmed live this doesn't
+    # work: extraVolumeMounts and extraEnv both render correctly, but
+    # extraVolumes is a dead values key for THIS subchart specifically -
+    # charts/gitlab/charts/praefect/templates/statefulset.yaml's own
+    # volumes: list never calls the gitlab.extraVolumes helper at all
+    # (only volumeMounts does), so the mount has nothing to mount and the
+    # pod would fail to schedule. No values-only fix exists.
+    #
+    # Real fix: argocd-apps/apps/gitlab.yaml's ignoreDifferences now
+    # covers ConfigMap gitlab-praefect's `data` field, so Helm creates
+    # the object (with its own 3-node content) but ArgoCD stops
+    # reconciling its content afterward. The actual multi-node content
+    # lives in apps/gitlab/manifests/praefect-ha-configmap.yaml as a
+    # git-tracked reference/documentation copy (deployed under its own
+    # name, praefect-ha-config, harmless and otherwise unused) - the
+    # live gitlab-praefect ConfigMap gets kubectl-patched with that same
+    # content directly, same "documented but manually-applied"
+    # convention as every other cross-cluster secret in this plan.
 
   # GitLab Exporter for Prometheus metrics
   gitlab-exporter: