feat(gitea): upgrade 1.27.3 -> 28.3.0

Gitea dropped the "1." prefix; 28.x is the successor of 1.27.
- image 28.3.0, update.range >=28.0.0 <29.0.0, Renovate ceiling <29.0.0
- drop GITEA__server__DOMAIN (no longer read in 28, ROOT_URL is the source)
- declare RUN_RETENTION_DAYS=400, EGRESS_MODE=lax (no allow list: the OIDC
  login source is not gated by the egress policy in 28.3.0), and
  DISABLE_REGISTRATION=true (28's new default)
- document autoRollbackOnFailedHealth as inert (no ImagePolicy is rendered);
  rollback is a PVC restore because the DB migration is one-way

Co-Authored-By: Claude Opus 5.5 <[email protected]>

catalog/gitea.yaml

@@ -10,7 +10,7 @@
 name: gitea
 kind: container
 source:
-  image: gitea/gitea:1.27.3     # pinned recent stable tag (R-UPD-01); update.range governs advancement
+  image: gitea/gitea:28.3.0     # pinned recent stable tag (R-UPD-01); update.range governs advancement
 # Headless-install bootstrap (formerly apps/gitea-bootstrap-patch.yaml; now first-class via the
 # ServiceDefinition env/envFrom/lifecycle fields, schema >=1.2.0). Gitea must come up INSTALLED
 # without the interactive web wizard and with a FIXED, persistent SECRET_KEY, so all of this is
@@ -23,14 +23,43 @@ env:
       secretKeyRef:
         name: gitea-bootstrap
         key: secret-key
-  - name: GITEA__server__DOMAIN              # correct public clone/redirect URLs for the TLS-terminated host
-    value: gitea.${BASE_DOMAIN}
+  # ROOT_URL is the ONLY source of the instance domain since Gitea 28 (go-gitea/gitea#39400): [server]
+  # DOMAIN is no longer read, and the SSH domain defaults from ROOT_URL too. GITEA__server__DOMAIN was
+  # removed in the 28 upgrade; the stale DOMAIN line environment-to-ini already wrote into app.ini is
+  # inert. Correct public clone/redirect URLs for the TLS-terminated host come from this one value.
   - name: GITEA__server__ROOT_URL
     value: https://gitea.${BASE_DOMAIN}/
   - name: GITEA__actions__ENABLED            # Phase 6 CI/CD: declared (not implicit upstream default) so the
     value: "true"                            # in-cluster act_runner (ns gitea-actions) registers against it
   - name: GITEA__actions__DEFAULT_ACTIONS_URL  # resolve `uses: <org>/<action>@ref` from github.com (cluster
     value: github                              # has internet egress; not air-gapped)
+  # Gitea 28 added run retention (go-gitea/gitea#38855): completed runs, with their jobs, logs and
+  # artifacts, are deleted by the cleanup_action_runs cron after RUN_RETENTION_DAYS. Upstream's default
+  # (400) is kept but DECLARED, so the deletion horizon is visible here rather than implicit. The spec
+  # repo states no CI-history retention requirement; 0 would mean keep forever.
+  - name: GITEA__actions__RUN_RETENTION_DAYS
+    value: "400"
+  # Gitea 28 (go-gitea/gitea#39426) puts webhooks, the OAuth2 avatar fetch and OpenID 2.0 behind an
+  # egress policy: in the default lax mode, PUBLIC targets are allowed and private/loopback/CGNAT
+  # targets need an IP or CIDR entry in [security] ALLOWED_HOST_LIST (a hostname entry is NOT enough
+  # for a private address). DECLARED lax with an EMPTY allow list, deliberately:
+  #   * the Keycloak OIDC login source is NOT gated by it. In 28.3.0 the openidConnect provider is
+  #     goth's, built with its default HTTP client (services/auth/source/oauth2/providers_openid.go);
+  #     egress.NewSecurityPolicy is used only by routers/web/auth/oauth.go (avatar fetch, and
+  #     [oauth2_client] UPDATE_AVATAR is off here) and modules/auth/openid (OpenID 2.0, unused).
+  #     So keycloak.<domain> resolving to the private Gateway address in-cluster does not matter.
+  #   * this instance has no webhooks and no mirrors (measured 2026-11-07), and 1.27 already refused
+  #     private webhook targets by default, so nothing that worked before is newly denied.
+  # Adding an entry here would only WIDEN the webhook SSRF surface. Add the narrowest CIDR (e.g. the
+  # Gateway address /32) only if a real private webhook target appears.
+  - name: GITEA__security__EGRESS_MODE
+    value: lax
+  # Gitea 28 (go-gitea/gitea#39400) disables LOCAL self-registration unless DISABLE_REGISTRATION is
+  # explicitly false; 1.27 defaulted it open. Declared true: accounts arrive via Keycloak only.
+  # OAuth2 auto-registration below is unaffected — routers/web/auth/oauth.go gates it on
+  # ALLOW_ONLY_INTERNAL_REGISTRATION and ENABLE_AUTO_REGISTRATION, not on DISABLE_REGISTRATION.
+  - name: GITEA__service__DISABLE_REGISTRATION
+    value: "true"
   - name: GITEA_ADMIN_USERNAME               # break-glass local admin creds (consumed by the postStart hook)
     valueFrom:
       secretKeyRef:
@@ -233,9 +262,14 @@ auth:
   # recovery tools (docs/15 "Availability caveat"). No secret is embedded here.
 update:
   channel: stable               # R-UPD-01
-  range: ">=1.22.0 <2.0.0"      # stay on the 1.x stable line
+  range: ">=28.0.0 <29.0.0"     # Gitea dropped the "1." prefix at 28.0.0 (successor of 1.27); stay on 28.x
   cadence: "0 4 * * *"
-  autoRollbackOnFailedHealth: true   # R-UPD-03
+  # R-UPD-03. INERT FOR THIS SERVICE, and it must stay that way: this flag renders only an annotation
+  # on a Flux ImagePolicy, and apps/ is rendered --no-image-automation (ci/render-golden.sh), so no
+  # ImagePolicy exists and the Deployment (strategy Recreate) is never auto-reverted. That matters
+  # because a Gitea upgrade (1.27 -> 28 included) MIGRATES THE SQLITE DB ONE-WAY: an image revert onto
+  # a migrated DB is not a rollback. Roll Gitea back by RESTORING THE DATA PVC from its pre-upgrade backup.
+  autoRollbackOnFailedHealth: true
 observability:
   metrics: true
   slis: