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ajet-chat/docs/prd/auth-gw.md
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PRD: Auth Gateway

Module: auth-gw/ | Namespace: ajet.chat.auth-gw.* Status: v1 | Last updated: 2026-02-17

1. Overview

The Auth Gateway is the single edge entry point for all client traffic. It terminates sessions, validates tokens, and reverse-proxies authenticated requests to internal services (API, Web SM, TUI SM). It also handles OAuth login flows and session management.

2. Architecture

Client → (nginx TLS, prod) → Auth Gateway → API Service
                                           → Web Session Manager
                                           → TUI Session Manager

Auth GW has direct PG access for session/token table lookups — this avoids a round-trip to the API for every request.

3. Route Table

Path Pattern Target Auth Required Description
GET / Web SM Session Web app root
GET /app/* Web SM Session Web app pages
GET /sse/* Web SM Session SSE streams for web
POST /web/* Web SM Session Web form submissions / Datastar signals
GET,POST /api/* API Session or API Token REST API
GET /tui/sse/* TUI SM Session SSE streams for TUI clients
POST /tui/* TUI SM Session TUI client signals
POST /api/webhooks/*/incoming API Webhook Token Incoming webhooks (bypass session auth)
GET /auth/login Self None Login page (OAuth provider buttons)
GET /auth/callback/:provider Self None OAuth callback
POST /auth/logout Self Session Logout (destroy session)
GET /setup/providers Self None Setup wizard step 1: configure OAuth providers
POST /setup/providers Self None Setup wizard step 1: save OAuth provider config
GET /setup/community Self Session Setup wizard step 3: create first community
POST /setup/community Self Session Setup wizard step 3: submit community creation
GET /invite/:code Self None Invite landing page → redirect to login if needed
GET /health Self None Health check

4. Authentication Flows

4.1 Session Token Validation

Every authenticated request follows this flow:

1. Extract token from Cookie: ajet_session=<base64url-token>
2. bcrypt-verify token against sessions.token_hash
3. Check sessions.expires_at > now
4. If valid:
   a. Extend session TTL (rolling expiry) — async, don't block request
   b. Inject headers: X-User-Id, X-User-Role, X-Community-Id, X-Trace-Id
   c. Proxy to target service
5. If invalid/expired: redirect to /auth/login (web) or 401 (API/TUI)

Rolling expiry: Each valid request extends expires_at by the session TTL (default: 30 days). This is done asynchronously to avoid adding latency.

Token format: 32 random bytes, base64url-encoded (43 characters). Stored as bcrypt hash.

4.2 API Token Validation

For Authorization: Bearer <token> requests to /api/*:

1. Extract token from Authorization header
2. bcrypt-verify against api_tokens.token_hash
3. Check api_tokens.expires_at > now (if set)
4. Check scopes allow the requested operation
5. If valid: inject X-User-Id (api_user's owner), X-Trace-Id
6. If invalid: 401

4.3 OAuth Login Flow

Supported providers: GitHub, Gitea, Generic OIDC

Provider storage: OAuth providers are stored in the oauth_providers DB table and are configurable at runtime via admin endpoints (/api/admin/oauth-providers). On first startup, if the oauth_providers table is empty, any providers configured via env vars (:oauth config) are auto-migrated to the DB.

1. User visits /auth/login
2. Auth GW loads enabled providers from oauth_providers table
3. Page shows provider buttons for each enabled provider
4. User clicks provider → redirect to provider's authorize URL
5. Provider redirects to /auth/callback/:provider with code
6. Auth GW exchanges code for access token
7. Auth GW fetches user profile from provider
8. Look up oauth_accounts by (provider, provider_user_id):
   a. EXISTS: load user, create session
   b. NOT EXISTS: create user + oauth_account, create session
9. Set session cookie, redirect to / (or to pending invite if present)

OAuth config shape (fallback — auto-migrated to DB on first startup):

{:oauth
 {:github {:client-id "..." :client-secret "..." :enabled true}
  :gitea  {:client-id "..." :client-secret "..." :base-url "https://gitea.example.com" :enabled true}
  :oidc   {:client-id "..." :client-secret "..." :issuer-url "https://auth.example.com" :enabled false}}}

After migration, provider config is read exclusively from the DB. The :oauth config key serves only as a seed for initial deployment and is ignored once providers exist in the DB.

Generic OIDC: Uses .well-known/openid-configuration discovery. Requires openid, profile, email scopes.

4.4 Admin Setup Wizard (First-Deployment Bootstrap)

The setup wizard is a multi-step flow handled by Auth GW for first-time deployment. It activates when the system_settings table indicates setup is incomplete (no setup_completed flag).

Step 1 — Configure OAuth Providers (no auth required):
1. User hits any route on a fresh deployment
2. Auth GW checks system_settings: setup_completed?
   - Not completed: redirect to /setup/providers
   - Completed: normal login flow
3. /setup/providers shows a form to configure at least one OAuth provider
   (provider type, client ID, client secret, base URL / issuer URL)
4. Admin submits provider config → saved to oauth_providers table
5. Auth GW redirects to /auth/login with the newly configured provider(s)

Step 2 — Admin Login via OAuth:
6. Admin logs in via one of the just-configured OAuth providers
7. First user is created with admin/owner privileges

Step 3 — Create First Community:
8. After login, redirect to /setup/community (rendered by Auth GW, not Web SM)
9. Admin enters community name, slug auto-generated
10. POST creates community (user becomes owner, #general created)
11. system_settings.setup_completed = true
12. Redirect to /app

Subsequent community creation (by already-authenticated users) uses the Web SM /setup page.

4.5 Invite Flow

1. User visits /invite/:code
2. Auth GW checks invite validity (exists, not expired, not exhausted)
   - Invalid: show error page
   - Valid: store invite code in cookie/session, redirect to /auth/login
3. After OAuth login, if pending invite code:
   a. Accept invite (join community)
   b. Redirect to community

5. Reverse Proxy Behavior

Request forwarding:

  • Strip auth headers from original request
  • Inject: X-User-Id, X-User-Role, X-Community-Id, X-Trace-Id, X-Forwarded-For
  • Forward request body, method, path, query string unchanged
  • SSE: hold connection open, stream response bytes through

Response forwarding:

  • Pass through status code, headers, body unchanged
  • For SSE responses: stream chunks as they arrive (no buffering)

Service discovery (v1): Static config — all services on localhost with configured ports.

{:services
 {:api    {:host "localhost" :port 3001}
  :web-sm {:host "localhost" :port 3002}
  :tui-sm {:host "localhost" :port 3003}}}

6. Rate Limiting

Endpoint Pattern Limit Window
POST /auth/login 10 1 min per IP
POST /auth/callback/* 10 1 min per IP
POST /api/* 60 1 min per user
GET /api/* 120 1 min per user
POST /api/webhooks/*/incoming 30 1 min per webhook
GET /sse/*, GET /tui/sse/* 5 1 min per user (connection attempts)

Implementation: In-memory token bucket (atom-based). No Redis needed for v1 (single instance).

7. Session Cookie

Name: ajet_session
Value: <base64url-encoded-token>
Attributes:
  HttpOnly: true
  Secure: true (prod only)
  SameSite: Lax
  Path: /
  Max-Age: 2592000 (30 days)

8. Test Cases

8.1 Session Validation

ID Test Description
AUTH-T1 Valid session cookie Request proxied with injected headers
AUTH-T2 Expired session Returns 401 (API) or redirect to login (web)
AUTH-T3 Invalid/tampered token Returns 401
AUTH-T4 Missing cookie Returns 401 (API) or redirect to login (web)
AUTH-T5 Session TTL extension Valid request extends expires_at
AUTH-T6 Concurrent requests Multiple requests with same session all succeed

8.2 API Token Validation

ID Test Description
AUTH-T7 Valid API token Request proxied with X-User-Id
AUTH-T8 Expired API token Returns 401
AUTH-T9 Invalid scope Returns 403 (scope mismatch)
AUTH-T10 Bearer header format Correctly parses Bearer <token>

8.3 OAuth Flow

ID Test Description
AUTH-T11 GitHub OAuth success Code exchanged, user created/found, session set, redirected
AUTH-T12 Gitea OAuth success Same as above for Gitea
AUTH-T13 OIDC OAuth success Uses discovery document, same flow
AUTH-T14 OAuth invalid code Returns error, redirects to login with error message
AUTH-T15 OAuth provider down Returns 502 with friendly error
AUTH-T16 Existing user re-login Finds existing user via oauth_accounts, creates new session
AUTH-T17 New user first login Creates user + oauth_account + session
AUTH-T18 OAuth state parameter CSRF protection via state param validated on callback

8.4 Admin Setup Wizard

ID Test Description
AUTH-T19 Fresh deploy redirects to setup Any route with setup_completed=false redirects to /setup/providers
AUTH-T20 Step 1: configure OAuth provider POST /setup/providers saves provider to oauth_providers table
AUTH-T21 Step 1: requires at least one provider POST /setup/providers with empty config returns 422
AUTH-T22a Step 2: login via configured provider After provider setup, /auth/login shows newly configured provider
AUTH-T22b Step 3: first user becomes owner After OAuth + community creation, user has owner role
AUTH-T22c Setup completed flag set After community creation, system_settings.setup_completed = true
AUTH-T22d Subsequent users see normal login With setup_completed=true, normal login page shown
AUTH-T22e Setup routes blocked after completion /setup/providers returns 403 when setup_completed=true

8.5 Invite Flow

ID Test Description
AUTH-T22 Valid invite → login → join Full invite acceptance flow works
AUTH-T23 Expired invite Shows error page
AUTH-T24 Exhausted invite Shows error page
AUTH-T25 Already-member invite Accepts gracefully, redirects to community

8.7 Reverse Proxy

ID Test Description
AUTH-T26 API route proxied /api/channels → forwarded to API service
AUTH-T27 Web route proxied / → forwarded to Web SM
AUTH-T28 TUI route proxied /tui/sse → forwarded to TUI SM
AUTH-T29 SSE streaming SSE response streamed without buffering
AUTH-T30 Target service down Returns 502
AUTH-T31 Headers injected X-User-Id, X-Trace-Id present on proxied request
AUTH-T32 Original auth headers stripped Client cannot forge X-User-Id

8.8 Rate Limiting

ID Test Description
AUTH-T33 Under limit Requests succeed normally
AUTH-T34 Over limit Returns 429 with Retry-After header
AUTH-T35 Rate limit per-user Different users have independent limits
AUTH-T36 Rate limit per-IP for auth OAuth callback rate limited by IP

8.9 Logout

ID Test Description
AUTH-T37 Logout destroys session POST /auth/logout deletes session from DB, clears cookie
AUTH-T38 Logout with invalid session Returns 200 (idempotent), clears cookie

8.10 Health Check

ID Test Description
AUTH-T39 Health check GET /health returns 200 with service status
AUTH-T40 Health check (DB down) Returns 503 with degraded status

9. Service Configuration

9.1 Config Shape

{:server {:host "0.0.0.0" :port 3000}
 :db     {:host "localhost" :port 5432 :dbname "ajet_chat"
          :user "ajet" :password "..." :pool-size 5}
 :oauth  {:github {:client-id "..." :client-secret "..." :enabled true}
          :gitea  {:client-id "..." :client-secret "..." :base-url "https://gitea.example.com" :enabled false}
          :oidc   {:client-id "..." :client-secret "..." :issuer-url "https://auth.example.com" :enabled false}}
          ;; ↑ Fallback seed only — auto-migrated to oauth_providers DB table on first startup.
          ;;   Ignored once providers exist in DB. Manage providers via admin API after setup.
 :services {:api    {:host "localhost" :port 3001}
            :web-sm {:host "localhost" :port 3002}
            :tui-sm {:host "localhost" :port 3003}}
 :session {:ttl-days 30
           :cookie-name "ajet_session"
           :cookie-secure true}           ;; false in dev
 :rate-limit {:enabled true}
 :cors {:allowed-origins ["https://chat.example.com"]
        :allowed-methods [:get :post :put :delete :options]
        :allowed-headers ["Content-Type" "Authorization" "X-Trace-Id"]
        :max-age 86400}}

9.2 CORS Configuration

CORS headers applied to all responses:

Access-Control-Allow-Origin: <configured origin or request Origin if in allowed list>
Access-Control-Allow-Methods: GET, POST, PUT, DELETE, OPTIONS
Access-Control-Allow-Headers: Content-Type, Authorization, X-Trace-Id
Access-Control-Allow-Credentials: true
Access-Control-Max-Age: 86400
  • Dev mode: Allow http://localhost:* origins
  • Prod mode: Strict origin whitelist from config
  • Preflight requests: OPTIONS handled and returned immediately (no proxy)

9.3 Audit Logging

What's logged:

  • All admin actions: kick, ban, mute, role change, channel delete, webhook create/delete, invite create/revoke
  • Authentication events: login success, login failure, logout, session expiry
  • Rate limit violations

Audit log table (in PostgreSQL, written by Auth GW):

audit_log (
  id uuid PK,
  actor_id uuid FK→users NULL,     -- NULL for unauthenticated events
  action text,                      -- 'login', 'kick', 'ban', 'channel.delete', etc.
  target_type text NULL,            -- 'user', 'channel', 'community', etc.
  target_id uuid NULL,
  community_id uuid NULL,
  ip_address inet,
  metadata jsonb,                   -- extra context (reason, duration, etc.)
  created_at timestamptz
)
idx_audit_log_actor ON audit_log(actor_id, created_at)
idx_audit_log_community ON audit_log(community_id, created_at)

Note: Auth GW writes audit logs directly to PG (it has DB access). API sends audit-worthy events to Auth GW via NATS subject chat.audit — Auth GW subscribes and persists them.

9.4 Middleware Pipeline

1. CORS headers (preflight short-circuit)
2. Request ID generation (X-Trace-Id if not present)
3. Request logging
4. Rate limiting (per-IP for auth, per-user for API)
5. Route matching
6.   Auth endpoints → handle directly (OAuth, login page, logout)
7.   Health check → handle directly
8.   Webhook endpoints → webhook token validation → proxy to API
9.   All other → session/token validation → header injection → proxy to target
10. Response logging (status, duration)

9.5 Startup / Shutdown Sequence

Startup:

1. Load config (EDN + env vars)
2. Create DB connection pool (HikariCP)
3. Auto-migrate OAuth providers from :oauth config to oauth_providers table (if table is empty)
4. Load enabled OAuth providers from DB
5. Initialize rate limiter (in-memory atom)
6. Start http-kit server
7. Log "Auth Gateway started on port {port}"

Shutdown (graceful):

1. Stop accepting new connections
2. Wait for in-flight requests (max 30s)
3. Close DB connection pool
4. Log "Auth Gateway stopped"

10. Login Page UI Mock (Hiccup rendered by Auth GW)

┌──────────────────────────────────────┐
│                                      │
│          ┌──────────────┐            │
│          │   ajet chat  │            │
│          └──────────────┘            │
│                                      │
│     Sign in to continue              │
│                                      │
│     ┌──────────────────────────┐     │
│     │  ◉ Continue with GitHub  │     │  ← providers loaded from DB
│     └──────────────────────────┘     │
│     ┌──────────────────────────┐     │
│     │  ◉ Continue with Gitea   │     │
│     └──────────────────────────┘     │
│     ┌──────────────────────────┐     │
│     │  ◉ Continue with SSO     │     │  ← only if OIDC provider in DB
│     └──────────────────────────┘     │
│                                      │
│     ─── or accepting invite ───      │  ← only if invite code present
│     Joining: My Team                 │
│                                      │
└──────────────────────────────────────┘

11. Error Pages

Auth GW renders simple HTML error pages for:

Status Page When
401 Unauthorized Invalid/expired session (web requests redirect to /auth/login instead)
403 Forbidden Valid session but insufficient permission
404 Not Found Unknown route
429 Rate Limited Too many requests — shows retry countdown
502 Bad Gateway Target service unreachable
503 Service Unavailable Auth GW degraded (DB down)
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