serverAppConfigs/docs/Infrastructure/Authentik.md

Authentik — the homelab's SSO / OIDC provider

Authentik is the single sign-on (SSO) and OpenID Connect (OIDC) provider for the homelab. It fronts the Caddy vhosts that do not carry their own application-level authentication. Apps that have their own login (Grafana, Gitea, OpenWebUI, Jellyfin, the *arr stack, Pi-hole) are not wrapped in forward_auth — they handle their own session.

• Version: 2026.8.0 (pinned in dankclaw/compose.yaml)
• Host: dankclaw (192.168.0.143)
• Name: auth.franksdank.cloud
• Stack: 3 compose services — authentik-postgres, authentik-server, authentik-worker (see Pi-hole for the LAN-DNS pattern)

Why Authentik

The comparison that chose it (against Authelia, Keycloak, Zitadel, Ory) is in .docaudit/research/auth.md. In short: full OIDC with single-logout, a web GUI for all configuration, a native Caddy forward_auth outpost, and a footprint that fits on a 3-user homelab (~1–1.5 GB idle). Redis was removed in 2025.10, so the stack is 3 services, not 4.

Architecture

graph LR
    subgraph Browser
        U[User]
    end
    subgraph Caddy [Caddy - auth gate]
        FA[forward_auth]
    end
    subgraph AK [Authentik]
        SRV[server :9000]
        WKR[worker]
        PG[(postgres)]
        OUT[outpost /auth/caddy]
    end
    subgraph App [Target app]
        A1[SearXNG / Hermes / Prometheus<br/>RomM / Copyparty / homepage]
    end

    U -->|1. GET /| FA
    FA -->|2. GET /outpost.../auth/caddy| OUT
    OUT -->|3. no session: 302 login| U
    U -->|4. login at auth.franksdank.cloud| SRV
    SRV --> PG
    WKR --> PG
    SRV -->|5. 2xx: session valid| FA
    FA -->|6. proxy with headers| A1

1. The browser hits a protected vhost (e.g. search.franksdank.cloud).
2. Caddy forward_auth clones the request to the Authentik outpost (/outpost.goauthentik.io/auth/caddy).
3. With no valid session, the outpost returns a 302 to the Authentik login page (auth.franksdank.cloud).
4. The user logs in at Authentik (email + password, TOTP/WebAuthn MFA, or an upstream provider).
5. On the next request the outpost returns 2xx; Caddy copies the X-Authentik-* headers and proxies to the app.

The three compose services

Service	Role	Image
authentik-postgres	PostgreSQL 16 (users, flows, sessions, events)	docker.io/library/postgres:16-alpine
authentik-server	Core + admin API + the embedded Caddy outpost (port 9000)	ghcr.io/goauthentik/server:2026.8.0
authentik-worker	Background tasks (event processing, provider sync, flows)	ghcr.io/goauthentik/server:2026.8.0

• Postgres is the only stateful store. Sessions, caching, and WebSockets moved to PostgreSQL in 2025.10 (Redis removed).
• Server and worker run the same image; the command selects the role (server / worker).
• The worker runs as 0:0 (rootless: container root maps to the host user that owns the data dir).
• Data persists under /home/dank/authentik/ (bind mounts, repo policy — no named volumes).

Caddy integration

The Caddyfile wraps the no-auth vhosts in a route block. The pattern (one example; the others are identical):

search.franksdank.cloud {
	route {
		# 1. The outpost path is proxied to Authentik (login UI + session).
		reverse_proxy /outpost.goauthentik.io/* authentik-server:9000
		# 2. forward_auth checks the session before serving the app.
		forward_auth authentik-server:9000 {
			uri /outpost.goauthentik.io/auth/caddy
			copy_headers X-Authentik-Username X-Authentik-Groups X-Authentik-Email X-Authentik-Name
			trusted_proxies private_ranges
		}
		# 3. The app.
		reverse_proxy 192.168.0.143:8081
	}
}

Vhosts protected by forward_auth: the homepage (franksdank.cloud, www.franksdank.cloud), SearXNG, Hermes, Prometheus, RomM, Copyparty. The auth.franksdank.cloud vhost proxies to the server directly (no forward_auth — it is the login).

Configuration (secrets)

Two secrets live in the host .env (git-ignored; placeholders in .env.example):

• AUTHENTIK_PG_PASS — the PostgreSQL password. Generate: openssl rand -base64 32.
• AUTHENTIK_SECRET_KEY — the server's signing key. Generate: openssl rand -base64 48.

First-time setup

1. ./scripts/deploy.sh dankclaw — pulls, starts the 3 services (postgres health-gated), reloads Caddy.
2. Open https://auth.franksdank.cloud — the initial setup wizard runs. It creates the superuser (email + password) and generates the DB schema.
3. In the admin interface: Directory → Applications → add a Proxy application (or an OAuth2/OpenID Connect provider) for each vhost you protect. The Caddy outpost reads the application's policy.
4. For apps with native OIDC (Grafana, Gitea, OpenWebUI): add an OAuth2/OpenID Connect provider, create the app with the correct redirect URI, and paste the client_id / client_secret into the app's SSO settings.

Operations

• Health: https://auth.franksdank.cloud/-/health/ (the server healthcheck probes this).
• Logs: podman logs authentik-server / podman logs authentik-worker.
• Backups: pg_dump the authentik-postgres database (the single source of truth). The /home/dank/authentik/ dir holds media + static files.
• Upgrades: bump the image tag in dankclaw/compose.yaml, run ./scripts/deploy.sh dankclaw. Authentik migrates the schema on startup.

Failure modes

Symptom	Cause	Fix
Every vhost 502s at the outpost	authentik-server down	podman logs authentik-server; check postgres health
Login loops (302 → login → 302)	trusted_proxies / X-Forwarded-* mismatch	Confirm Caddy sets X-Forwarded-For; the outpost trusts private_ranges
"Invalid signature" on the outpost	AUTHENTIK_SECRET_KEY differs between server and worker	Both services read the same .env var; re-deploy
Postgres "password authentication failed"	AUTHENTIK_PG_PASS changed after first init	Reset via pg_ctl or re-init the data dir

Cross-references

• Caddy — the reverse proxy that carries the forward_auth directives
• Pi-hole — the LAN DNS that resolves auth.franksdank.cloud
• Network Architecture — the flat naming scheme
• Research: .docaudit/research/auth.md — the full provider comparison