turnstone/docs/oidc.md

OpenID Connect (OIDC) Single Sign-On

Turnstone supports OpenID Connect for federated authentication, allowing users to log in with their existing corporate identity provider instead of managing a separate password. OIDC is opt-in: when configured, the login screen shows a "Continue with SSO" button alongside the existing username/password form. When not configured, the login experience is unchanged.

Any OIDC-compliant provider works: Google, Okta, Azure AD, Keycloak, Auth0, OneLogin, and others that publish a .well-known/openid-configuration discovery document.

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Prerequisites

1. A registered confidential OIDC client at your identity provider
2. The client's redirect URI must include: https://your-turnstone-host/v1/api/auth/oidc/callback
3. A local admin user must exist in Turnstone (complete the initial setup wizard before enabling OIDC)

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Configuration

OIDC is configured via environment variables (preferred) or the [oidc] section of config.toml. Environment variables take precedence when both are set.

Variable	Required	Default	Description
TURNSTONE_OIDC_ISSUER	Yes	—	Issuer URL (e.g. https://accounts.google.com). Must serve /.well-known/openid-configuration.
TURNSTONE_OIDC_CLIENT_ID	Yes	—	OAuth 2.0 client ID from your provider
TURNSTONE_OIDC_CLIENT_SECRET	Yes	—	OAuth 2.0 client secret (confidential client)
TURNSTONE_OIDC_SCOPES	No	openid email profile	Space-separated OAuth scopes to request
TURNSTONE_OIDC_PROVIDER_NAME	No	SSO	Display name for the login button (e.g. "Google", "Okta")
TURNSTONE_OIDC_ROLE_CLAIM	No	—	ID token claim containing role/group values (see Role Mapping)
TURNSTONE_OIDC_ROLE_MAP	No	—	Mapping from claim values to Turnstone role IDs (see Role Mapping)
TURNSTONE_OIDC_PASSWORD_ENABLED	No	true	Set to false to hide the password form and block all username/password logins (including admin). API tokens continue to work.
TURNSTONE_OIDC_REDIRECT_BASE	Yes	—	Externally-reachable origin for the OIDC redirect URI (e.g. https://app.example.com). Without this, OIDC will refuse to start. The previous Host-header fallback was unsafe under permissive reverse proxies.
TURNSTONE_OIDC_TRUSTED_ENDPOINT_HOSTS	No	—	Comma-separated list of additional hostnames whose endpoints the IdP discovery document is allowed to reference. See Cross-host endpoints.
TURNSTONE_OIDC_ALLOW_PRIVATE_NETWORK	No	false	Allow the issuer (and its discovered endpoints) to resolve to private/internal addresses — needed for a self-hosted IdP on an internal network. See Self-hosted and internal IdPs.

All four required fields — issuer, client ID, client secret, and TURNSTONE_OIDC_REDIRECT_BASE — must be set. If any are missing OIDC is disabled at startup (an error is logged when only redirect_base is missing) and the login screen shows only the password form.

Redirect base (required)

TURNSTONE_OIDC_REDIRECT_BASE pins the redirect URI sent to the identity provider to a known externally-visible origin. Set it to the public origin of your Turnstone deployment:

TURNSTONE_OIDC_REDIRECT_BASE=https://app.example.com

The resulting callback URL will be https://app.example.com/v1/api/auth/oidc/callback — register this as the authorized redirect URI in your identity provider.

OIDC will refuse to start when this variable is unset. There is no Host-header fallback: a permissive reverse proxy or direct backend access would otherwise let an attacker spoof Host and steer the IdP redirect to a callback origin they control.

Cross-host endpoints

By default, every endpoint in the IdP discovery document (token_endpoint, jwks_uri, userinfo_endpoint) must share the issuer's (scheme, host, port). This prevents a hostile or compromised IdP from redirecting the token-exchange POST (which carries client_secret) to an arbitrary host, and prevents JWKS fetches from being aimed at internal services.

A few public IdPs legitimately split endpoints across hostnames. Google and Microsoft Entra ID are the canonical examples:

IdP	Issuer host	Cross-host endpoint(s)
Google	accounts.google.com	oauth2.googleapis.com, www.googleapis.com, openidconnect.googleapis.com
Microsoft Entra	login.microsoftonline.com	graph.microsoft.com (userinfo)

Both sets are built in — operators using https://accounts.google.com or https://login.microsoftonline.com/<tenant>/v2.0 need no extra configuration. (Entra's discovery document advertises userinfo_endpoint on graph.microsoft.com, distinct from the issuer host.)

For other IdPs whose discovery document references a non-issuer host, extend the allow-list explicitly:

TURNSTONE_OIDC_TRUSTED_ENDPOINT_HOSTS=token.example.com,keys.example.com

The same scheme / no-userinfo / SSRF rules apply to allow-listed hosts — this knob only relaxes the same-origin check, not the security gates. Each entry is a hostname (no scheme, no path).

Self-hosted and internal IdPs

By default Turnstone refuses an issuer whose hostname resolves to a private or internal address:

OIDCError: endpoint URL resolves to non-public address (10.0.0.5): https://auth.example.site

This is SSRF hardening, not a licensing or product restriction: the OIDC flow makes server-side HTTP requests (discovery, JWKS, token exchange), and refusing non-public destinations keeps a mistyped or maliciously steered issuer from aiming those fetches at internal services. For a self-hosted IdP (Keycloak, Authentik, Dex, …) on a private network, opt in explicitly in config.toml:

[oidc]
allow_private_network = true

or via TURNSTONE_OIDC_ALLOW_PRIVATE_NETWORK=true (the env var wins when both are set).

The opt-in admits private-range (RFC 1918), unique-local, site-local, CGNAT (100.64/10, where overlay VPNs commonly assign hosts), and loopback addresses. Link-local, multicast, reserved ranges and known cloud-metadata endpoints stay refused even with the opt-in — no legitimate IdP lives there. An address is judged by what it actually reaches, so an IPv6 transition address (NAT64, 6to4, Teredo) wrapping an internal IPv4 is treated exactly as that IPv4 would be. The HTTPS requirement and the same-origin endpoint checks are unaffected.

This knob only affects the login-flow IdP configured here. OAuth endpoints advertised by remote MCP servers are untrusted input and are always held to the strict public-address rule.

Model gateway credentials

The same OIDC registration can authenticate model gateways. A model definition with auth_mode = "entra_obo" (Entra grant profile) or auth_mode = "rfc8693_obo" (RFC 8693 token-exchange profile) redeems the driving user's captured credential for its exact obo_audience; auth_mode = "entra_app" uses the registration's client ID and secret with Entra client credentials. All three bind the result through the provider SDK's native credential option rather than injecting an override header. The grant mode is never inferred: missing user context or a failed OBO mint cannot switch a delegated definition to client credentials.

Each dynamic mode pairs with the grant profile whose dialect it names: entra_obo and entra_app require obo_grant_profile = "entra"; rfc8693_obo requires obo_grant_profile = "rfc8693". The pairing is enforced when a write chooses a (auth_mode, obo_audience) pair — a same-pair edit of a row saved before the pairing rule keeps working — and at runtime a mismatched legacy row refuses to mint with cause=grant_profile_mismatch and no IdP traffic. RFC 8693 client-credentials is not implemented.

The delegated modes need the MCP encryption key, a credential captured for the driving user, and delegated/admin-consented permission to the audience. rfc8693_obo additionally carries obo_scopes, the space-separated scope list its exchange leg requests: exchange-capable IdPs that gate audiences behind optional scopes refuse the exchange without it ("Requested audience not available"), which is why the scope-less Entra-named mode could never mint on that profile (issue #955). Scopes are stored shape-checked only — whether a value satisfies the IdP stays the IdP's call at mint time. Turning capture_user_credential off later stops new captures but does not invalidate credentials already stored, so existing users keep minting. entra_app requires a confidential-client secret. Configure the permitted resource IDs in the runtime setting model.auth_audience_allowlist before saving dynamic model definitions. De-listing an audience later blocks every write that would arm or re-aim a definition at it, but does not stop aliases already configured from minting — disabling the row (the admin.models disarm lever) is what stops minting. See Settings for permissions, failure policy, and lane identity rules.

An unrecognised obo_grant_profile is warned about at startup and rejected at the write choke points: configuring an oauth_obo MCP server or a dynamic model alias returns a 400 that echoes the configured value, so the typo is the diagnosis. At runtime an unknown profile never mints — the mint legs resolve by exact name; the full cause detail is logged once per audience, and every affected call still logs its per-turn fallback or refusal naming the alias, the target audience, and the last recorded cause (cause= — for example unsupported_grant_profile or oidc_not_enabled) — so a pre-existing row degrades loudly, with the reason visible mid-incident even after the once-per-process line has rotated out of retained logs, rather than silently swapping per-user attribution for the shared static key.

The [security] token encryption key is deployment-wide, not per-host: rows are encrypted with MultiFernet and carry no key id, so every host that reads them needs the same keyring. That includes the console, which mints for coordinator-hosted sessions. A node that needs the key and lacks it refuses to start; the console starts but withholds its coordinator subsystem and shows the key requirement as the remediation error instead of failing silently at call time.

config.toml alternative

[oidc]
issuer = "https://accounts.google.com"
client_id = "your-client-id"
client_secret = "your-client-secret"
scopes = "openid email profile"
provider_name = "Google"
role_claim = "groups"
password_enabled = true
redirect_base = "https://app.example.com"
# Self-hosted IdP on an internal network (see "Self-hosted and internal IdPs")
allow_private_network = false

[oidc.role_map]
admin = "builtin-admin"
engineering = "builtin-operator"

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Provider-Specific Setup

Google

1. Go to Google Cloud Console > APIs & Services > Credentials
2. Click Create Credentials > OAuth 2.0 Client ID
3. Application type: Web application
4. Add authorized redirect URI: https://your-turnstone-host/v1/api/auth/oidc/callback
5. Copy the Client ID and Client secret

TURNSTONE_OIDC_ISSUER=https://accounts.google.com
TURNSTONE_OIDC_CLIENT_ID=123456789.apps.googleusercontent.com
TURNSTONE_OIDC_CLIENT_SECRET=GOCSPX-...
TURNSTONE_OIDC_PROVIDER_NAME=Google

Okta

1. In the Okta Admin Console, go to Applications > Create App Integration
2. Sign-in method: OIDC - OpenID Connect
3. Application type: Web Application
4. Add sign-in redirect URI: https://your-turnstone-host/v1/api/auth/oidc/callback
5. Note the Issuer (your Okta domain, e.g. https://dev-123456.okta.com)

TURNSTONE_OIDC_ISSUER=https://dev-123456.okta.com
TURNSTONE_OIDC_CLIENT_ID=0oaXXXXXXXXXXXXX
TURNSTONE_OIDC_CLIENT_SECRET=...
TURNSTONE_OIDC_PROVIDER_NAME=Okta
TURNSTONE_OIDC_ROLE_CLAIM=groups
TURNSTONE_OIDC_ROLE_MAP="admin:builtin-admin,everyone:builtin-operator"

Azure AD (Entra ID)

1. In the Azure Portal, go to App registrations > New registration
2. Redirect URI: Web > https://your-turnstone-host/v1/api/auth/oidc/callback
3. Under Certificates & secrets, create a new Client secret and copy the value immediately
4. The issuer URL is https://login.microsoftonline.com/{tenant-id}/v2.0

TURNSTONE_OIDC_ISSUER=https://login.microsoftonline.com/YOUR_TENANT_ID/v2.0
TURNSTONE_OIDC_CLIENT_ID=xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx
TURNSTONE_OIDC_CLIENT_SECRET=...
TURNSTONE_OIDC_PROVIDER_NAME="Azure AD"
TURNSTONE_OIDC_ROLE_CLAIM=roles
TURNSTONE_OIDC_ROLE_MAP="Admin:builtin-admin,User:builtin-operator"

Keycloak

1. In the Keycloak Admin Console, select your Realm
2. Go to Clients > Create client
3. Client type: OpenID Connect
4. Set Client authentication to On (confidential)
5. Add valid redirect URI: https://your-turnstone-host/v1/api/auth/oidc/callback
6. The issuer URL is https://keycloak.example.com/realms/your-realm

TURNSTONE_OIDC_ISSUER=https://keycloak.example.com/realms/your-realm
TURNSTONE_OIDC_CLIENT_ID=turnstone
TURNSTONE_OIDC_CLIENT_SECRET=...
TURNSTONE_OIDC_PROVIDER_NAME=Keycloak
TURNSTONE_OIDC_ROLE_CLAIM=realm_access.roles
TURNSTONE_OIDC_ROLE_MAP="admin:builtin-admin,operator:builtin-operator"

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Role Mapping

OIDC role mapping assigns Turnstone roles to users based on claims in the ID token. This is optional — without it, OIDC users are provisioned with the builtin-viewer role (read-only access) by default.

Configuration

Set TURNSTONE_OIDC_ROLE_CLAIM to the name of the claim in the ID token that contains the user's group or role memberships. Then set TURNSTONE_OIDC_ROLE_MAP to map claim values to Turnstone role IDs.

The role map is a comma-separated list of claim_value:turnstone_role pairs:

TURNSTONE_OIDC_ROLE_CLAIM=groups
TURNSTONE_OIDC_ROLE_MAP="admin:builtin-admin,engineering:builtin-operator,viewer:builtin-viewer"

Behavior

• Synced on every login: roles are added when new claim values appear, and OIDC-assigned roles are revoked when the corresponding claim value is no longer present. Roles assigned manually (or by other sources) are never touched — only roles with assigned_by="oidc" are subject to revocation.
• List or string: the claim value can be a JSON array (["admin", "engineering"]) or a single string ("admin"). Both are handled correctly.
• Unknown values: claim values not present in the role map are silently ignored.
• Missing roles: if the role map references a Turnstone role ID that does not exist in the database, the assignment is skipped (no error).
• Evaluated on every login: roles are checked and applied each time the user authenticates via OIDC, so new group memberships are picked up on the next login.

assigned_by markers

Role assignments record an assigned_by value that controls how the sync logic treats them. OIDC-driven flows use two distinct markers:

• oidc — set by claim-driven role mapping; revoked automatically on the next login when the corresponding claim value is no longer present.
• oidc-default — applied to brand-new OIDC users who have no claim-mapped roles, as a safety net so they still get builtin-viewer access on first login. Survives subsequent logins regardless of claim contents and is never revoked by apply_role_mapping.

Built-in Roles

Role ID	Permissions
builtin-admin	All permissions
builtin-operator	read, write, workstreams.create, workstreams.close
builtin-viewer	read

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User Provisioning

When a user logs in via OIDC for the first time, Turnstone automatically creates a local user account:

1. The OIDC identity (issuer + sub claim) is stored in the oidc_identities table and linked to the new user
2. The username is derived from the preferred_username claim, falling back to the email local part, with deduplication if needed
3. The display name comes from the name claim, falling back to preferred_username or email
4. The user's password hash is set to a sentinel value (!oidc) — OIDC users cannot log in with a password

On subsequent logins, the existing user is matched by (issuer, sub) and the last_login timestamp is updated. Role mapping is re-evaluated on every login.

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OIDC-Only Mode

To enforce OIDC for all logins and hide the password form, set:

TURNSTONE_OIDC_PASSWORD_ENABLED=false

In this mode the login screen shows only the "Continue with SSO" button. The password form, token toggle, and sign-in button are all hidden. All username/password logins are blocked at the API level, including admin accounts.

The first admin account must be created via the setup wizard (with a password) before OIDC is enabled. The setup wizard always works regardless of this setting because it is only available when zero users exist in the database.

API token login (POST /v1/api/auth/login with a ts_ token) continues to work regardless of this setting. JWTs and API tokens are the supported authentication methods. OIDC-only mode affects password-based authentication only.

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Login Flow

Both the server and console support OIDC login. The flow is identical:

1. The browser fetches GET /v1/api/auth/status at page load
2. If the response includes oidc_enabled: true, the login screen shows a "Continue with {provider_name}" button
3. Clicking the button navigates to GET /v1/api/auth/oidc/authorize
4. Turnstone generates a state token, nonce, and PKCE verifier, stores them in the database, and redirects the browser to the identity provider's authorization endpoint
5. The user authenticates at the identity provider
6. The IdP redirects back to GET /v1/api/auth/oidc/callback?code=...&state=...
7. Turnstone validates the state, exchanges the authorization code for tokens using the PKCE verifier, validates the ID token against the provider's JWKS public keys, provisions or matches the user, and issues a Turnstone JWT
8. The browser is redirected to /?oidc_success=1 with the JWT set in an HttpOnly session cookie
9. The browser JavaScript detects the oidc_success query parameter, strips it from the URL, hides the login overlay, and calls onLoginSuccess() to initialize the application

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API Endpoints

Method	Path	Auth	Description
GET	/v1/api/auth/oidc/authorize	Public	Redirects to identity provider
GET	/v1/api/auth/oidc/callback	Public	Handles IdP callback, issues JWT

Both endpoints are public (no authentication required) because they are part of the login flow itself.

Auth status response

When OIDC is enabled, GET /v1/api/auth/status includes additional fields:

{
  "auth_enabled": true,
  "has_users": true,
  "setup_required": false,
  "oidc_enabled": true,
  "oidc_provider_name": "Google",
  "password_enabled": true
}

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Database Schema

Migration 018 creates two tables:

CREATE TABLE oidc_identities (
    issuer      TEXT NOT NULL,
    subject     TEXT NOT NULL,
    user_id     TEXT NOT NULL,
    email       TEXT NOT NULL DEFAULT '',
    created     TEXT NOT NULL,
    last_login  TEXT NOT NULL,
    PRIMARY KEY (issuer, subject)
);

CREATE INDEX idx_oidc_identities_user_id ON oidc_identities(user_id);

CREATE TABLE oidc_pending_states (
    state          TEXT PRIMARY KEY,
    nonce          TEXT NOT NULL,
    code_verifier  TEXT NOT NULL,
    audience       TEXT NOT NULL,
    created_at     TEXT NOT NULL
);

The oidc_identities table links an OIDC subject (identified by issuer + subject) to a Turnstone user_id. A single user can have multiple OIDC identities (e.g. from different providers).

The oidc_pending_states table stores authorization flow state for callback validation. Entries are automatically cleaned up after 5 minutes.

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Security Notes

• Authorization Code Flow with PKCE: the recommended OAuth 2.0 flow for web applications. PKCE prevents authorization code interception attacks even without a client secret (though the client secret is still used for additional security).
• ID token validation: all tokens are validated using the provider's JWKS public keys (RS256 or ES256). The signature, issuer, audience, and expiry are all checked.
• State parameter: a cryptographically random state token prevents CSRF attacks on the callback endpoint. The state is stored server-side and verified on callback.
• Nonce: a random nonce is included in the authorization request and verified in the ID token to prevent replay attacks.
• Client secret: never leaves the server — it is only used in the server-to-IdP token exchange, not exposed to the browser.
• OIDC users cannot use password login: the sentinel password hash (!oidc) ensures verify_password() always rejects password attempts for OIDC-provisioned users.
• Rate limiting: the callback endpoint shares the login rate limiter (5 attempts per 5-minute window per IP).
• State TTL: pending authorization states expire after 5 minutes. Expired states are lazily cleaned up on each callback.
• Setup guard: OIDC login requires at least one local admin user to exist. This ensures the initial admin account is always created via the setup wizard with a password, not hijacked by an external identity.

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Troubleshooting

"OIDC not configured"

All four required environment variables must be set: TURNSTONE_OIDC_ISSUER, TURNSTONE_OIDC_CLIENT_ID, TURNSTONE_OIDC_CLIENT_SECRET, and TURNSTONE_OIDC_REDIRECT_BASE. Check that none are empty or whitespace-only.

"OIDC enabled but TURNSTONE_OIDC_REDIRECT_BASE is unset"

This error is logged when the three credential variables are set but TURNSTONE_OIDC_REDIRECT_BASE is missing. OIDC is disabled at startup to prevent Host-header-derived redirect URI spoofing. Set the variable to your service's externally-visible origin (e.g. https://app.example.com) and restart the server. See Redirect base for the rationale.

Discovery silently disables OIDC with "host does not match issuer"

The IdP discovery document points token_endpoint, jwks_uri, or userinfo_endpoint at a hostname that doesn't share the issuer's origin. If the IdP is legitimate, add the additional hostname(s) to TURNSTONE_OIDC_TRUSTED_ENDPOINT_HOSTS. Google is allow-listed automatically; see Cross-host endpoints.

"Login session expired"

The authorization flow must complete within 5 minutes. If the user takes too long at the identity provider, the pending state expires. Try again.

"Initial setup required"

OIDC login is blocked until at least one local admin user exists. Complete the setup wizard first (navigate to the Turnstone URL and follow the prompts to create an admin user with a password).

Discovery fails at startup

Check that the issuer URL is reachable from the Turnstone server and serves a valid /.well-known/openid-configuration document. The server logs the discovery attempt at startup:

OIDC discovery failed for https://your-issuer.example.com: ...

OIDC is automatically disabled when discovery fails. Restart the server after fixing the connectivity issue.

Redirect URI mismatch

The redirect URI configured at the identity provider must exactly match https://your-host/v1/api/auth/oidc/callback. Common issues:

• Scheme mismatch: the redirect uses https:// — make sure TLS is configured or a reverse proxy sets the X-Forwarded-Proto header
• Port mismatch: if running on a non-standard port, include it in the redirect URI
• Path mismatch: the path must include the /v1 API version prefix

User not assigned expected roles

Check that:

1. TURNSTONE_OIDC_ROLE_CLAIM matches the exact claim name in the ID token (case-sensitive)
2. TURNSTONE_OIDC_ROLE_MAP maps the correct claim values to valid Turnstone role IDs
3. The roles referenced in the map exist in the database (check the admin panel > Roles tab)
4. The identity provider is configured to include the claim in the ID token (some providers require explicit scope or claim configuration)