Integrate Forgejo with Authentik OIDC

Refactor Authentik blueprints into common.yaml (shared admins group),
grafana.yaml (updated with !Find and groups scope), and forgejo.yaml
(new provider + application). Add forgejo-client-secret to ExternalSecret
and worker deployment. Configure Forgejo oauth2_client for auto-registration
with login-based account linking to safely preserve existing accounts.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

ansible/roles/forgejo/templates/app.ini.j2

@@ -77,6 +77,12 @@ PASSWORD_HASH_ALGO = pbkdf2_hi
 [oauth2]
 JWT_SECRET = {{ forgejo_oauth2_jwt_secret }}
 
+[oauth2_client]
+ENABLE_AUTO_REGISTRATION = true
+ACCOUNT_LINKING = login
+USERNAME = nickname
+REGISTER_EMAIL_CONFIRM = false
+
 [actions]
 ENABLED = {{ forgejo_actions_enabled | lower }}
 DEFAULT_ACTIONS_URL = {{ forgejo_actions_default_url }}

argocd/manifests/authentik/configmap-blueprint.yaml

@@ -5,14 +5,13 @@ metadata:
   name: authentik-blueprints
   namespace: authentik
 data:
-  grafana.yaml: |
+  common.yaml: |
     version: 1
     metadata:
-      name: BlumeOps Grafana SSO
+      name: BlumeOps Common Identity
       labels:
-        blueprints.goauthentik.io/description: "Grafana OIDC provider and application"
+        blueprints.goauthentik.io/description: "Shared groups and identity resources"
     entries:
-      # admins group — gates access to admin-only applications
       - model: authentik_core.group
         id: admins-group
         identifiers:
@@ -20,6 +19,13 @@ data:
         attrs:
           name: admins
 
+  grafana.yaml: |
+    version: 1
+    metadata:
+      name: BlumeOps Grafana SSO
+      labels:
+        blueprints.goauthentik.io/description: "Grafana OIDC provider and application"
+    entries:
       # OAuth2 provider for Grafana
       - model: authentik_providers_oauth2.oauth2provider
         id: grafana-provider
@@ -42,6 +48,7 @@ data:
             - !Find [authentik_providers_oauth2.scopemapping, [scope_name, openid]]
             - !Find [authentik_providers_oauth2.scopemapping, [scope_name, email]]
             - !Find [authentik_providers_oauth2.scopemapping, [scope_name, profile]]
+            - !Find [authentik_providers_oauth2.scopemapping, [scope_name, groups]]
           sub_mode: hashed_user_id
           include_claims_in_id_token: true
 
@@ -62,10 +69,67 @@ data:
         identifiers:
           order: 0
           target: !KeyOf grafana-app
-          group: !KeyOf admins-group
+          group: !Find [authentik_core.group, [name, admins]]
         attrs:
           target: !KeyOf grafana-app
-          group: !KeyOf admins-group
+          group: !Find [authentik_core.group, [name, admins]]
+          order: 0
+          enabled: true
+          negate: false
+          timeout: 30
+
+  forgejo.yaml: |
+    version: 1
+    metadata:
+      name: BlumeOps Forgejo SSO
+      labels:
+        blueprints.goauthentik.io/description: "Forgejo OIDC provider and application"
+    entries:
+      # OAuth2 provider for Forgejo
+      - model: authentik_providers_oauth2.oauth2provider
+        id: forgejo-provider
+        identifiers:
+          name: Forgejo
+        attrs:
+          name: Forgejo
+          authorization_flow: !Find [authentik_flows.flow, [slug, default-provider-authorization-implicit-consent]]
+          invalidation_flow: !Find [authentik_flows.flow, [slug, default-provider-invalidation-flow]]
+          client_type: confidential
+          client_id: forgejo
+          client_secret: !Env AUTHENTIK_FORGEJO_CLIENT_SECRET
+          redirect_uris:
+            - matching_mode: strict
+              url: https://forge.ops.eblu.me/user/oauth2/authentik/callback
+          signing_key: !Find [authentik_crypto.certificatekeypair, [name, authentik Self-signed Certificate]]
+          property_mappings:
+            - !Find [authentik_providers_oauth2.scopemapping, [scope_name, openid]]
+            - !Find [authentik_providers_oauth2.scopemapping, [scope_name, email]]
+            - !Find [authentik_providers_oauth2.scopemapping, [scope_name, profile]]
+            - !Find [authentik_providers_oauth2.scopemapping, [scope_name, groups]]
+          sub_mode: hashed_user_id
+          include_claims_in_id_token: true
+
+      # Forgejo application — linked to the OAuth2 provider
+      - model: authentik_core.application
+        id: forgejo-app
+        identifiers:
+          slug: forgejo
+        attrs:
+          name: Forgejo
+          slug: forgejo
+          provider: !KeyOf forgejo-provider
+          meta_launch_url: https://forge.ops.eblu.me
+          policy_engine_mode: any
+
+      # Policy binding — restrict Forgejo to admins group
+      - model: authentik_policies.policybinding
+        identifiers:
+          order: 0
+          target: !KeyOf forgejo-app
+          group: !Find [authentik_core.group, [name, admins]]
+        attrs:
+          target: !KeyOf forgejo-app
+          group: !Find [authentik_core.group, [name, admins]]
           order: 0
           enabled: true
           negate: false

argocd/manifests/authentik/deployment-worker.yaml

@@ -58,6 +58,11 @@ spec:
                 secretKeyRef:
                   name: authentik-config
                   key: grafana-client-secret
+            - name: AUTHENTIK_FORGEJO_CLIENT_SECRET
+              valueFrom:
+                secretKeyRef:
+                  name: authentik-config
+                  key: forgejo-client-secret
           volumeMounts:
             - name: blueprints
               mountPath: /blueprints/custom

argocd/manifests/authentik/external-secret.yaml

@@ -41,3 +41,7 @@ spec:
       remoteRef:
         key: "Authentik (blumeops)"
         property: grafana-client-secret
+    - secretKey: forgejo-client-secret
+      remoteRef:
+        key: "Authentik (blumeops)"
+        property: forgejo-client-secret

docs/changelog.d/feature-forgejo-authentik-oidc.feature.md

@@ -0,0 +1 @@
+Integrate Forgejo with Authentik OIDC for single sign-on with group-based admin propagation.

docs/explanation/federated-login.md

@@ -62,9 +62,16 @@ Authentik runs on [[ringtail]]'s k3s cluster while most services run on indri's
 
 No k8s-internal DNS crosses cluster boundaries. Everything uses the `*.ops.eblu.me` domain.
 
+## Forgejo
+
+[[forgejo]] authenticates against Authentik using the same OIDC flow as Grafana. The auth source is created via CLI (`forgejo admin auth add-oauth`) rather than config file — it lives in Forgejo's SQLite database.
+
+Account linking is configured with `ACCOUNT_LINKING = login`: when an Authentik user's email matches an existing local account, Forgejo prompts for the local password to confirm the link. This safely preserves the existing `eblume` account with all its API tokens, SSH keys, and repository ownership.
+
+The `admins` group in Authentik maps to Forgejo admin status, enabling centralized admin management.
+
 ## Future Work
 
-- **Forgejo OIDC:** Make Forgejo an OIDC client of Authentik (deferred — existing `eblume` account needs careful migration)
 - **Additional services:** ArgoCD, Miniflux, Immich, Zot (see [[harden-zot-registry]])
 
 ## Related

docs/reference/services/authentik.md

@@ -39,11 +39,13 @@ Uses the shared CNPG `blumeops-pg` cluster on [[indri]], accessed cross-cluster
 
 ## Blueprints
 
-Authentik configuration is managed via Blueprints (YAML) stored as a ConfigMap mounted into the worker at `/blueprints/custom/`. Current blueprints define:
+Authentik configuration is managed via Blueprints (YAML) stored as a ConfigMap mounted into the worker at `/blueprints/custom/`. Current blueprints:
 
-- `admins` group
+- **`common.yaml`** — shared identity resources (`admins` group)
-- Grafana OAuth2 provider (client ID: `grafana`)
+- **`grafana.yaml`** — Grafana OAuth2 provider, application, and policy binding
-- Grafana application with group-based policy binding
+- **`forgejo.yaml`** — Forgejo OAuth2 provider, application, and policy binding
+
+All providers include the `groups` scope mapping for group-based admin propagation.
 
 Blueprint file: `argocd/manifests/authentik/configmap-blueprint.yaml`
 
@@ -52,8 +54,9 @@ Blueprint file: `argocd/manifests/authentik/configmap-blueprint.yaml`
 | Client | Status |
 |--------|--------|
 | [[grafana]] | Active |
+| [[forgejo]] | Active |
 
-Future clients: [[forgejo]], [[argocd]], [[miniflux]], [[zot]]
+Future clients: [[argocd]], [[miniflux]], [[zot]]
 
 ## Secrets
 
@@ -64,6 +67,7 @@ Injected via [[external-secrets]] from the "Authentik (blumeops)" 1Password item
 | `secret-key` | Authentik secret key |
 | `db-password` | PostgreSQL password |
 | `grafana-client-secret` | OIDC client secret for Grafana |
+| `forgejo-client-secret` | OIDC client secret for Forgejo |
 | `api-token` | Authentik API token |
 
 ## Container Image

docs/reference/services/forgejo.md

@@ -1,6 +1,6 @@
 ---
 title: Forgejo
-modified: 2026-02-19
+modified: 2026-02-20
 tags:
   - service
   - git
@@ -79,7 +79,18 @@ This is a bootstrapping requirement - the PAT enables IaC for all other secrets.
 
 ## Identity Provider
 
-[[authentik]] is the BlumeOps OIDC identity provider and source of truth for user identity. Forgejo will eventually authenticate against Authentik as an OIDC client, with user provisioning managed in Authentik. This migration is deferred — the existing `eblume` account has extensive automations that need careful migration.
+[[authentik]] is the BlumeOps OIDC identity provider and source of truth for user identity. Forgejo authenticates against Authentik as an OIDC client.
+
+**Configuration:**
+- OAuth2 provider and application defined in Authentik blueprints (`argocd/manifests/authentik/configmap-blueprint.yaml`)
+- Auth source created via `forgejo admin auth add-oauth` (lives in Forgejo's SQLite database, not app.ini)
+- `[oauth2_client]` section in `app.ini.j2` controls auto-registration and account linking behavior
+
+**Account linking:** `ACCOUNT_LINKING = login` — when an Authentik user's email matches an existing local account, Forgejo prompts for the local password to confirm the link. This preserves existing accounts, API tokens, SSH keys, and repository ownership.
+
+**Group-based admin:** The `admins` group in Authentik maps to Forgejo admin status via `--admin-group admins` on the auth source. Manage admin access in Authentik, not Forgejo.
+
+**Break-glass:** Local password login always works. Authentik SSO is additive — if Authentik is down, log in with local credentials.
 
 ## Future: Public Access