Authentication & Authorization

Set up authentication and authorization for incoming requests

Authorization directives can be used in your schema to define granular authorization rules on the field definition level. Documentation can be found at @authenticated and @requiresScopes.

Cosmo router supports authenticating incoming requests using JWKS authentication. The JSON Web Key Set (JWKS) is a set of keys that contains the public keys used to verify any JSON Web Token (JWT) issued by the authorization server and signed using a signing algorithm.

To enable an authentication provider, add it to your configuration

Current Configuration

In the current router version, the configuration and behavior of authentication have been redesigned. Instead of specifying a configuration per JWKS endpoint, you can now list multiple endpoints where all header rules apply to. Each JWKS endpoint can optionally specify a whitelist of supported JWT algorithms.

Configuration

config.yaml

authentication:
  jwt:
    jwks:
      - url: https://example.com/.well-known/jwks.json
        refresh_interval: 1m
        algorithms: ["RS256"]
        refresh_unknown_kid:
          enabled: true
          max_wait: 2m
          interval: 30s
          burst: 5
      - url: https://example2.com/.well-known/jwks.json
        refresh_interval: 2m
        # optional list of allowed algorithms per JWKS
        algorithms: ["RS256", "EdDSA", "HS512"]
        audiences:
          - http://aud1
          - http://aud2
      - symmetric_algorithm: HS256
        secret: <your_secret>
        header_key_id: some-key-id
    header_name: Authorization # Optional, Authorization is the default value
    header_value_prefix: Bearer # Optional, Bearer is the default value
    header_sources:
      - type: header
        name: X-Auth-Token
        value_prefixes: [Token, MyToken]
      - type: header
        name: X-Authorization

The router configuration facilitates the setup of multiple JWKS (JSON Web Key Set) endpoints, each customizable with distinct retrieval settings. It allows specification of supported JWT (JSON Web Token) algorithms per endpoint. It also allows the use of secrets for symmetric algorithms, as it would be a security risk to expose them over a JWKS endpoint. Centralizing header rules application across all keys from every JWKS endpoint simplifies management. This setup grants centralized control while offering flexibility in the retrieval and processing of keys.

For more information on the attributes, visit the auth configuration parameter section page here.

Old Router configuration (< 0.168.1)

config.yaml

authentication:
  providers:
    - name: My Auth Provider # Optional, used for error messages and diagnostics
      jwks: # JWKS provider configuration
        url: https://example.com/.well-known/jwks.json # URL to load the JWKS from (Authorization server)
        header_names: [Authorization] # Optional, Authorization is the default value
        header_value_prefixes: [Bearer] # Optional, Bearer is the default value
        refresh_interval: 1m # Optional, How often the JWK is refreshed

Using multiple authentication providers is also supported. If authentication with any of the providers succeeds, the claims from the token are decoded and made available through the request pipeline. Notice that providers are tried in the same order as they are defined in the configuration and once a provider authenticates a request, no other providers are tried.

Enforce authentication

By default, requests without authentication information are allowed. Only requests with invalid authentication information (e.g. an incorrectly signed token) produce a 403 Forbidden response. To disable anonymous requests, use the Authorization configuration:

config.yaml

authorization:
  require_authentication: true

This causes requests without authorization information to produce a 401 Unauthorized

Authentication information is also available to custom modules. See Access Authenticated Information.

Forwarding authentication headers

By default, the router won’t forward authentication headers to subgraphs, but if desired this can be configured using Proxy capabilities.

Refreshing Unknown KIDs on Demand

When refresh_unknown_kid.enabled is set to true, the router will automatically attempt to refresh the JWKS (fetch updated keys) whenever it encounters a valid token with an unknown KID (Key ID). This is useful when key rotation has occurred but the router hasn’t picked up the new keys in its regular refresh cycle.

To prevent overwhelming the JWKS endpoint, this feature includes rate limiting controlled by the following parameters:

• burst: Maximum number of refreshes allowed without waiting. Internally, the router keeps a counter of available burst tokens. Each time the interval elapses, one token is replenished, up to the burst limit.
• interval: The time that must elapse between replenishing burst tokens, until the burst limit is reached.
• max_wait: Maximum time a refresh is allowed to wait. If the computed wait would exceed this value, the request is rejected immediately with a 401 Unauthorized status instead of waiting.

Rate Limiting Example

Let’s examine how rate limiting works with these settings:

refresh_unknown_kid:
  enabled: true
  burst: 1
  interval: 30s
  max_wait: 110s

If we send 6 simultaneous requests with unknown KIDs:

1. First request: JWKS refreshed immediately; 1 burst token is consumed.
2. Second request: Waits for 30s (interval × 1); a token is replenished after 30s.
3. Third request: Waits for 60s (interval × 2); a token is replenished after another 30s.
4. Fourth request: Waits for 90s (interval × 3); a token is replenished after another 30s.
5. Fifth request: Fails immediately (would require 120s wait > max_wait) with 401 Unauthorized.
6. Sixth request: Fails immediately (would require 150s wait > max_wait) with 401 Unauthorized.

The 2nd, 3rd and 4th requests are rate-limited because the burst capacity is set to 1. After the first request passes, the number of available burst tokens is 0 and subsequent requests must wait until the interval elapses. If burst were set to 2, the second request would also pass immediately.

The max_wait setting prevents excessive wait times. In this example, since the 5th and 6th requests would require waiting longer than the configured max_wait of 110s, they immediately return with a 401 Unauthorized status instead of attempting to refresh.