Fix GitLab Authentik SSO: restore providers list, populate real provider key

GITLAB_OMNIBUS_CONFIG (gitlab_rails['omniauth_providers'] = [...]) is
an omnibus-Docker-image-only convention. This chart's CNG webservice
image never processes it - confirmed via gitlab/charts/gitlab/
templates/_omniauth.tpl, which only reads
global.appConfig.omniauth.providers (a list of {secret,key} refs, each
pointing at a Secret key holding a whole YAML-encoded provider block
loaded via Ruby's YAML.load_file). So GITLAB_OMNIBUS_CONFIG was always
a silent no-op on both home and VPS - neither ever actually had SSO
configured despite gitlab-oidc-secret existing and looking correct.

Yesterday's fix for 'FailedMount: references non-existent secret key:
provider' removed the providers: list entirely instead of populating
that key - stopped the crash, but also silently deleted the only real
OIDC config path on both sites (no error, login page just lost its SSO
button). This restores providers: on both, and gitlab-oidc-secret's
ExternalSecret template now actually renders a provider key containing
a real YAML provider block (with the templated client_id/secret
substituted in), matching what _omniauth.tpl expects.

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

infrastructure/vps-standby/gitlab/manifests/oidc-secret.yaml

@@ -5,6 +5,13 @@
 # (infrastructure/vps-eso/manifests/clustersecretstore.yaml's policy,
 # applied live via vault CLI, not git-tracked - matches how every other
 # Vault policy/auth-method in this repo is set up).
+#
+# `provider` key added 2026-08-21: found live that GITLAB_OMNIBUS_CONFIG
+# (this app's values.yaml extraEnv) is an omnibus-image-only convention
+# the CNG webservice image never processes - see the matching comment
+# in apps/gitlab/manifests/external-secret-oidc.yaml (home) for the
+# full story. The real mechanism needs this key to hold a whole
+# YAML-encoded provider block, not raw client_id/secret strings.
 apiVersion: external-secrets.io/v1
 kind: ExternalSecret
 metadata:
@@ -23,6 +30,26 @@ spec:
       data:
         GITLAB_OIDC_CLIENT_ID: "{{ .clientId }}"
         GITLAB_OIDC_CLIENT_SECRET: "{{ .clientSecret }}"
+        provider: |
+          name: openid_connect
+          label: Authentik
+          args:
+            name: openid_connect
+            scope:
+              - openid
+              - profile
+              - email
+            response_type: code
+            issuer: 'https://auth.kube.huskypup.net/application/o/gitlab/'
+            discovery: true
+            client_auth_method: query
+            uid_field: sub
+            send_scope_to_token_endpoint: true
+            pkce: true
+            client_options:
+              identifier: '{{ .clientId }}'
+              secret: '{{ .clientSecret }}'
+              redirect_uri: 'https://gitlab.vps.huskypup.net/users/auth/openid_connect/callback'
   data:
     - secretKey: clientId
       remoteRef:

infrastructure/vps-standby/gitlab/values.yaml

@@ -64,15 +64,13 @@ global:
       key: password
 
   appConfig:
-    # NOTE: no `providers:` list here - found live 2026-08-21: the chart
-    # requires gitlab-oidc-secret to have a `provider` key (full YAML
-    # provider config) when this is set, and it never does - only
-    # GITLAB_OIDC_CLIENT_ID/SECRET, consumed via extraEnvFrom +
-    # GITLAB_OMNIBUS_CONFIG below instead (the actual mechanism
-    # configuring OIDC). Caused "FailedMount: references non-existent
-    # secret key: provider" blocking webservice/sidekiq/toolbox from ever
-    # starting - see the matching fix + full explanation in
-    # apps/gitlab/values.yaml (home).
+    # CORRECTED 2026-08-21 (see apps/gitlab/values.yaml (home) for the
+    # full story) - `providers:` list restored, now pointing at
+    # gitlab-oidc-secret's `provider` key which holds a real
+    # YAML-encoded provider block (manifests/oidc-secret.yaml), the
+    # actual mechanism the CNG webservice image processes.
+    # GITLAB_OMNIBUS_CONFIG below is an omnibus-image-only convention
+    # this image never reads - always a no-op here.
     omniauth:
       enabled: true
       allowSingleSignOn: ['openid_connect']
@@ -80,6 +78,9 @@ global:
       autoLinkUser: ['openid_connect']
       syncProfileFromProvider: ['openid_connect']
       syncProfileAttributes: ['email', 'name']
+      providers:
+        - secret: gitlab-oidc-secret
+          key: provider
 
 # GitLab's pre-upgrade hook checks the deployed version against a
 # previous-release ConfigMap to enforce supported upgrade paths - found