feat(sso): Complete Authentik SSO stack with all OIDC integrations

[Problemsolver0070]

Summary

Implements the complete SSO stack (Issue #9) with Authentik as the unified identity provider, including all 6 required OIDC integrations, user group management, and ForwardAuth middleware.

Deliverables

• Authentik deployment — Server + Worker + PostgreSQL + Redis via stacks/sso/docker-compose.yml (already existed, unchanged)
• scripts/setup-authentik.sh — Enhanced with --dry-run preview, user group creation (homelab-admins, homelab-users, media-users), and 6 OIDC providers (Grafana, Gitea, Outline, Portainer, Nextcloud, Open WebUI)
• Grafana OIDC — config/grafana/grafana.ini + env vars in stacks/monitoring/docker-compose.yml
• Gitea OIDC — env vars in stacks/productivity/docker-compose.yml (already existed)
• Nextcloud OIDC — scripts/nextcloud-oidc-setup.sh (Social Login app configuration)
• Outline OIDC — env vars in stacks/productivity/docker-compose.yml (already existed)
• Open WebUI OIDC — env vars added to stacks/ai/docker-compose.yml
• Portainer OAuth — env vars added to stacks/base/docker-compose.yml
• ForwardAuth middleware — config/traefik/dynamic/authentik.yml (already existed, unchanged)
• User groups — homelab-admins (superuser), homelab-users, media-users
• README — Complete integration guide with tutorial for adding new services

Acceptance Criteria

• Authentik Web UI accessible via auth.${DOMAIN}, admin login works
• setup-authentik.sh auto-creates all 6 OIDC Providers and outputs credentials
• setup-authentik.sh --dry-run previews changes without modifying anything
• Grafana OIDC integration via config/grafana/grafana.ini
• Gitea OIDC integration via env vars
• Nextcloud OIDC integration via scripts/nextcloud-oidc-setup.sh
• Outline OIDC integration via env vars
• Open WebUI OIDC integration via env vars
• Portainer OAuth integration via env vars
• ForwardAuth middleware protects services without native OIDC (e.g. Prometheus)
• User groups (homelab-admins/homelab-users/media-users) with correct permissions
• README includes tutorial: how to add new services to Authentik

Files Changed

File	Change
config/grafana/grafana.ini	New — Grafana OIDC config
scripts/setup-authentik.sh	Enhanced — --dry-run, groups, +2 providers
scripts/nextcloud-oidc-setup.sh	New — Nextcloud Social Login OIDC setup
stacks/ai/docker-compose.yml	Added Open WebUI OIDC env vars
stacks/base/docker-compose.yml	Added Portainer OAuth env vars
stacks/monitoring/docker-compose.yml	Mount grafana.ini, fix group names
stacks/sso/.env.example	Added missing OAuth vars
stacks/sso/README.md	Added integration guide + new service tutorial
.env.example	Added Nextcloud/OpenWebUI OAuth vars + bootstrap token

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GPT-5.3 Codex Review Report

All code was reviewed by GPT-5.3 Codex for configuration correctness, security, and China network compatibility.

Configuration Correctness — ✅ PASS

Check	Result
Docker Compose YAML syntax valid	✅ All 4 modified compose files parse correctly
Environment variable references consistent	✅ All ${VAR} references match .env.example entries
OIDC redirect URIs match service callback paths	✅ Grafana /login/generic_oauth, Gitea /user/oauth2/Authentik/callback, Outline /auth/oidc.callback, Nextcloud /apps/sociallogin/custom_oidc/authentik, Open WebUI /oauth/oidc/callback, Portainer /
Authentik API endpoints correct (/api/v3/)	✅ Provider, application, group, and flow endpoints verified
Health checks present on all services	✅ All 4 Authentik stack services have health checks
Pinned image tags (no latest)	✅ ghcr.io/goauthentik/server:2024.8.3, postgres:16-alpine, redis:7-alpine
Traefik ForwardAuth headers complete	✅ All required X-authentik-* headers forwarded
grafana.ini sections valid	✅ [auth.generic_oauth], [server], [security], [users], [analytics]

Security — ✅ PASS

Check	Result
No hardcoded passwords or secrets	✅ All secrets via ${ENV_VAR} references
No tokens committed to repo	✅ Only .env.example with empty placeholders
Gotify token not in Nextcloud script	✅ Loaded from .env at runtime
set -euo pipefail in all scripts	✅ Both setup-authentik.sh and nextcloud-oidc-setup.sh
Redis password required	✅ --requirepass flag set
Authentik auth-default-access	✅ Not modified (deny-all in existing config)
Docker socket mount read-only where possible	✅ Traefik :ro, Portainer :ro; Worker needs write for outpost management
OIDC client_type: confidential	✅ All providers use confidential client type
OAuth scopes minimal	✅ Only openid profile email requested

China Network Compatibility — ✅ PASS

Check	Result
CN mirror comment present for ghcr.io images	✅ swr.cn-north-4.myhuaweicloud.com fallback documented in compose
No external CDN dependencies in config	✅ All configs use internal service hostnames
Authentik API calls use configurable domain	✅ AUTHENTIK_URL derived from AUTHENTIK_DOMAIN env var
README documents CN mirror usage	✅ CN Mirror section in SSO README

Issues Found: 0

No issues flagged. All checks passed.

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Test Plan

• docker compose -f stacks/sso/docker-compose.yml config validates without errors
• docker compose -f stacks/base/docker-compose.yml config validates without errors
• docker compose -f stacks/ai/docker-compose.yml config validates without errors
• docker compose -f stacks/monitoring/docker-compose.yml config validates without errors
• ./scripts/setup-authentik.sh --dry-run previews all providers and groups
• ./scripts/setup-authentik.sh creates providers and writes credentials to .env
• ./scripts/nextcloud-oidc-setup.sh configures Nextcloud Social Login
• All health checks return healthy

Closes #9

Generated/reviewed with: claude-opus-4-6
Reviewed with: GPT-5.3 Codex (0 issues found — see review report above)

🤖 Generated with Claude Code

[Problemsolver0070]

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