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atauth CLAUDE.md
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ATAuth - AT Protocol OIDC Provider #

Overview #

ATAuth is an OpenID Connect (OIDC) Provider that uses AT Protocol OAuth (Bluesky) as the identity source. It allows applications to authenticate users via their Bluesky accounts.

Critical: Domain Configuration #

IMPORTANT: ATAuth staging MUST use workingtitle.zip domain, NOT arcnode.xyz.

Why: The user's PDS is at arcnode.xyz. If ATAuth is also on arcnode.xyz, the browser sends Sec-Fetch-Site: same-site to the PDS OAuth endpoint, which the PDS rejects. Using a different domain (workingtitle.zip) makes it cross-site, which is allowed.

Architecture #

OIDC Client (e.g., Audiobookshelf)
    ↓ redirects to
ATAuth (auth-staging.workingtitle.zip) - OIDC Provider
    ↓ redirects to
User's PDS (arcnode.xyz) - AT Protocol OAuth
    ↓ user authenticates, redirects back to
ATAuth (receives AT Proto tokens, issues OIDC tokens)
    ↓ redirects back to
OIDC Client (receives OIDC tokens)
  • Gateway: Node.js/Express 5, TypeScript, SQLite
  • Identity Source: AT Protocol OAuth (user's PDS, e.g., arcnode.xyz or bsky.social)
  • Token Format: ES256 signed JWTs
  • PKCE: Required for all flows

Deployment #

Current Production (DigitalOcean) #

  • Public URL: https://auth-staging.workingtitle.zip
  • Apricot Gateway: https://apricot.workingtitle.zip (routes /auth/* and /admin/* to ATAuth)
  • OIDC Discovery: https://auth-staging.workingtitle.zip/.well-known/openid-configuration
  • Cluster: DO Managed Kubernetes (storm-dr-cluster, nyc1)
  • Namespace: atauth
  • Registry: registry.digitalocean.com/ghostmesh-registry
  • Image: registry.digitalocean.com/ghostmesh-registry/atauth:latest
  • Storage: SQLite on do-block-storage PVC
  • Backups: Every 6 hours to Backblaze B2 (age encrypted, cronjob in backups namespace)

Deployment Process (Manual) #

# Build and push
docker build --platform linux/amd64 -t registry.digitalocean.com/ghostmesh-registry/atauth:latest .
docker push registry.digitalocean.com/ghostmesh-registry/atauth:latest

# Deploy
kubectl rollout restart deployment/atauth-gateway -n atauth

Local k3s (Suspended) #

Previously ran on k3s (Proxmox VMs 321/322) with two namespaces: atauth-staging (standalone) and apricot (integrated with PDS). Local k3s VMs shut down as of Feb 12, 2026. Config preserved in gateway/k8s/overlays/staging/ and gateway/k8s/overlays/production/.

Admin Access #

Admin Token #

The admin token is stored in Vaultwarden:

Using Admin API #

# Set token from Vaultwarden
export ADMIN_TOKEN="<token-from-vaultwarden>"

# List OIDC clients
curl -s "https://auth-staging.workingtitle.zip/admin/oidc/clients" \
  -H "Authorization: Bearer $ADMIN_TOKEN" | jq .

# Create/update client
curl -X POST "https://auth-staging.workingtitle.zip/admin/oidc/clients" \
  -H "Authorization: Bearer $ADMIN_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{
    "client_name": "My App",
    "redirect_uris": ["https://myapp.example.com/callback"],
    "grant_types": ["authorization_code", "refresh_token"],
    "token_endpoint_auth_method": "client_secret_basic"
  }'

OIDC Client Configuration #

Registered Clients #

Audiobookshelf #

Setting Value
Client ID audiobookshelf
Client Secret Vaultwarden → ATAuth/OIDC Clients/Audiobookshelf
Redirect URI https://audiobookshelf.cloudforest-basilisk.ts.net/auth/openid/callback
Grant Types authorization_code, refresh_token
Scopes openid, profile, email
PKCE Required

Note: Redirect URI is HTTPS without port (Tailscale serve handles TLS on port 443).

Secrets Storage #

All secrets in Vaultwarden (LXC 120 @ vaultwarden.cloudforest-basilisk.ts.net):

  • ATAuth/Admin Token - Staging
  • ATAuth/Admin Token - Production
  • ATAuth/OIDC Clients/Audiobookshelf
  • ATAuth/OIDC Key Secret

Infrastructure #

Cloudflare Configuration #

  • Account ID: abc90e3f264c71019a7f68204a5c4454
  • Tunnel ID: 600f069c-4c53-4a59-b1fd-57c5ad09c044
  • Routes:
    • auth-staging.workingtitle.zip → http://atauth-gateway.atauth.svc.cluster.local:80 (DO cluster)
    • apricot.workingtitle.zip → http://atauth-gateway.atauth.svc.cluster.local:80 (DO cluster)
    • auth-staging.arcnode.xyz → (DEPRECATED, causes same-site issues)

Security (Cloudflare) #

  • WAF: Cloudflare Managed Ruleset + OWASP Core (block mode)
  • Rate Limiting: 10 req/min on /oauth/token, /oauth/authorize, /auth/*
  • TLS: Minimum 1.3, Strict mode

Cluster Resources #

# Check deployment
kubectl -n atauth get pods
kubectl -n atauth logs -l app.kubernetes.io/part-of=atauth

# View/edit config
kubectl -n atauth get configmap atauth-gateway-config -o yaml

# Restart after config change
kubectl -n atauth rollout restart deployment atauth-gateway

User's PDS (arcnode.xyz) #

  • Server: Hetzner Cloud (pds-hetzner)
  • Public IP: 46.224.33.19
  • Tailscale: 100.89.0.112 (pds-hetzner)
  • SSH: ssh -i ~/.ssh/vaultnode_ed25519 root@100.89.0.112
  • OAuth Endpoint: https://arcnode.xyz/oauth/authorize
  • DID: did:plc:k23ujfuppr3hr4pxvtaz7jro
  • Handle: @bkb.arcnode.xyz

Audiobookshelf #

  • Location: LXC 107 on pv4
  • Tailscale IP: 100.115.188.60
  • URL: https://audiobookshelf.cloudforest-basilisk.ts.net (via Tailscale serve)
  • Internal: nginx (8080) → ABS (13378)
  • SSH via pv4: ssh root@pv4.cloudforest-basilisk.ts.net "pct exec 107 -- <command>"

Vaultwarden #

Testing #

Run Tests #

cd gateway
npm run test:unit    # Unit tests only
npm run test:e2e     # E2E tests only
npm run test         # All tests with watch
npm run test:run     # All tests once

Manual OIDC Flow Test #

# 1. Check discovery
curl -s "https://auth-staging.workingtitle.zip/.well-known/openid-configuration" | jq .

# 2. Check JWKS
curl -s "https://auth-staging.workingtitle.zip/.well-known/jwks.json" | jq .

# 3. Test in browser - go to Audiobookshelf and click "Login with OpenID"

API Endpoints #

OIDC Endpoints #

Endpoint Description
/.well-known/openid-configuration Discovery document
/.well-known/jwks.json Public signing keys
/oauth/authorize Authorization endpoint
/oauth/token Token exchange
/oauth/userinfo User claims
/oauth/revoke Token revocation

Admin Endpoints (requires Bearer token) #

Endpoint Description
GET /admin/oidc/clients List OIDC clients
POST /admin/oidc/clients Create OIDC client
GET /admin/oidc/clients/:id Get client details
PUT /admin/oidc/clients/:id Update client
DELETE /admin/oidc/clients/:id Delete client
GET /admin/sessions List sessions
GET /admin/keys List signing keys

Troubleshooting #

"Forbidden sec-fetch-site header same-site" #

Cause: ATAuth and user's PDS are on the same registrable domain. Fix: Use workingtitle.zip for ATAuth, not arcnode.xyz.

"invalid_redirect_uri" #

Cause: Redirect URI in request doesn't match registered client. Fix: Check client's registered redirect_uris match exactly (including https vs http, port, path).

Token refresh failures / Users logged out #

Cause: iOS app sends chunked encoding with empty body on refreshSession. Fix: nginx with proxy_pass_request_body off for that endpoint (handled on PDS side).