OAuth

Gloo Edge supports authentication via OpenID Connect (OIDC). OIDC is an identity layer on top of the OAuth 2.0 protocol. In OAuth 2.0 flows, authentication is performed by an external Identity Provider (IdP) which, in case of success, returns an Access Token representing the user identity. The protocol does not define the contents and structure of the Access Token, which greatly reduces the portability of OAuth 2.0 implementations.

The goal of OIDC is to address this ambiguity by additionally requiring Identity Providers to return a well-defined ID Token. OIDC ID tokens follow the JSON Web Token standard and contain specific fields that your applications can expect and handle. This standardization allows you to switch between Identity Providers - or support multiple ones at the same time - with minimal, if any, changes to your downstream services; it also allows you to consistently apply additional security measures like Role-based Access Control (RBAC) based on the identity of your users, i.e. the contents of their ID token (check out this guide for an example of how to use Gloo Edge to apply RBAC policies to JWTs).

In this guide, we will focus on the format of the Gloo Edge API for OIDC authentication.

Configuration format

Following is an example of an AuthConfig with an OIDC configuration (for more information on AuthConfig CRDs, see the main page of the authentication docs):

apiVersion: enterprise.gloo.solo.io/v1
kind: AuthConfig
metadata:
  name: oidc
  namespace: gloo-system
spec:
  configs:
  - oauth2:
      oidcAuthorizationCode:
        issuerUrl: theissuer.com
        appUrl: https://myapp.com
        authEndpointQueryParams:
          paramKey: paramValue
        callbackPath: /my/callback/path/
        clientId: myclientid
        clientSecretRef:
          name: my-oauth-secret
          namespace: gloo-system
        scopes:
        - email

The AuthConfig consists of a single config of type oauth. Let’s go through each of its attributes:

• issuer_url: The url of the OpenID Connect identity provider. Gloo Edge will automatically discover OpenID Connect configuration by querying the .well-known/openid-configuration endpoint on the issuer_url. For example, if you are using Google as an identity provider, Gloo Edge will expect to find OIDC discovery information at https://accounts.google.com/.well-known/openid-configuration.
• auth_endpoint_query_params: A map of query parameters appended to the issuer url in the form issuer_url?paramKey:paramValue. These query parameters are sent to the authorization endpoint when Gloo Edge initiates the OIDC flow. This can be useful when integrating Gloo Edge with some identity providers that require custom parameters to be sent to the authorization endpoint.
• app_url: This is the public URL of your application. It is used in combination with the callback_path attribute.
• callback_path: The callback path relative to the app_url. Once a user has been authenticated, the identity provider will redirect them to this URL. Gloo Edge will intercept requests with this path, exchange the authorization code received from the Identity Provider for an ID token, place the ID token in a cookie on the request, and forward the request to its original destination.

• client_id: This is the client id that you obtained when you registered your application with the identity provider.
• client_secret_ref: This is a reference to a Kubernetes secret containing the client secret that you obtained when you registered your application with the identity provider. The easiest way to create the Kubernetes secret in the expected format is to use glooctl, but you can use kubectl create secret or kubectl apply as well. If you use kubectl create secret, be sure to annotate the secret with *v1.Secret so that Gloo Edge detects the secret.
  • glooctl
  • kubectl create secret
  • kubectl apply

  
  glooctl create secret oauth --namespace gloo-system --name oidc --client-secret <client_secret_value>
  

  
  kubectl create secret generic oidc --from-literal=client-secret=<client_secret>
  kubectl annotate secret oidc resource_kind='*v1.Secret' # Important, since gloo-edge does not watch for opaque secrets without this setting
  

  
  apiVersion: v1
  kind: Secret
  type: extauth.solo.io/oauth
  metadata:
    name: oidc
    namespace: gloo-system
  data:
    # The value is a base64 encoding of the following YAML:
    # client_secret: secretvalue
    # Gloo Edge expects OAuth client secrets in this format.
    client-secret: Y2xpZW50U2VjcmV0OiBzZWNyZXR2YWx1ZQo=
  

• scopes: scopes to request in addition to the openid scope.

Cookie options

Use the cookieOptions field to customize cookie behavior:

• notSecure - Set the cookie to not secure. This is not recommended, but might be useful for demo/testing purposes.
• maxAge - The max age of the cookie in seconds. Leave unset for a default of 30 days (2592000 seconds). To disable cookie expiry, set explicitly to 0.
• path - The path of the cookie. If unset, it defaults to “/”. Set it explicitly to "" to avoid setting a path.
• domain - The domain of the cookie. The default value is empty and matches only the originating request. This is fine for cases where the VirtualService matches the host value that is also the redirect target of the IdP. However, this value is critical if the OAuth provider is redirecting the request to another subdomain, for example. Consider a case where a VirtualService matches requests to *.example.com and the IdP redirects its auth requests to subdomain.example.com. With default settings for domain, if a request comes in on other.example.com, the operation fails. The user is directed to the IdP login as expected but auth fails because the token-bearing cookie is not sent back to the proxy, since the request originates from a different subdomain. However, if this domain property is set to example.com, then the operation succeeds because the cookie is sent to any subdomain of example.com.

Example configuration:

apiVersion: enterprise.gloo.solo.io/v1
kind: AuthConfig
metadata:
  name: oidc-dex
  namespace: gloo-system
spec:
  configs:
  - oauth2:
      oidcAuthorizationCode:
        appUrl: http://localhost:8080/
        callbackPath: /callback
        clientId: gloo
        clientSecretRef:
          name: oauth
          namespace: gloo-system
        issuerUrl: http://dex.gloo-system.svc.cluster.local:32000/
        scopes:
        - email
        session:
          cookieOptions:
            notSecure: true
            maxAge: 3600

Logout URL

Gloo also supports specifying a logout url. When specified, accessing this url will trigger a deletion of the user session and revoke the user’s access token. This action returns with an empty 200 HTTP response.

Example configuration:

apiVersion: enterprise.gloo.solo.io/v1
kind: AuthConfig
metadata:
  name: oidc-dex
  namespace: gloo-system
spec:
  configs:
  - oauth2:
      oidcAuthorizationCode:
        appUrl: http://localhost:8080/
        callbackPath: /callback
        clientId: gloo
        clientSecretRef:
          name: oauth
          namespace: gloo-system
        issuerUrl: http://dex.gloo-system.svc.cluster.local:32000/
        scopes:
        - email
        logoutPath: /logout

When this URL is accessed, the user session and cookie are deleted. The access token on the server is also revoked based on the discovered revocation endpoint. You can also override the revocation endpoint through the DiscoveryOverride field in AuthConfig.

Sessions in Cookies

You can store the ID token, access token, and other tokens that are returned from your OIDC provider in a cookie on the client side. To do this, you configure your cookie options, such as the keyPrefix that you want to add to the token name, in the oauth2.oidcAuthorizationCode.session.cookie section of your authconfig as shown in the following example. After a client successfully authenticates with the OIDC provider, the tokens are stored in the Set-Cookie response header and sent to the client. If you set a keyPrefix value in your cookie configuration, the prefix is added to the name of the token before it is sent to the client, such as Set-Cookie: <myprefix>_id-token=<ID_token>. To prove successful authentication with the OIDC provider in subsequent requests, clients send their tokens in a Cookie header.

Cookie headers can have a maximum size of 4KB. If you find that your cookie header exceeds this value, you can either limit the size of the cookie header or store the tokens in Redis and send back a Redis session ID instead.

Example configuration:

apiVersion: enterprise.gloo.solo.io/v1
kind: AuthConfig
metadata:
  name: oidc-dex
  namespace: gloo-system
spec:
  configs:
  - oauth2:
      oidcAuthorizationCode:
        appUrl: http://localhost:8080/
        callbackPath: /callback
        clientId: gloo
        clientSecretRef:
          name: oauth
          namespace: gloo-system
        issuerUrl: http://dex.gloo-system.svc.cluster.local:32000/
        scopes:
        - email
        session:
          cookie:
            keyPrefix: "my_cookie_prefix"

Symmetric cookie encryption

By default, the tokens that are sent in the cookie header are not encrypted and can be manipulated through malicious attacks. To encrypt the cookie values, you can add a cipherConfig section to your session configuration as shown in the following example.

1. Create a secret with your encryption key. Note that the key must be 32 bytes in length.

   glooctl create secret encryptionkey --name my-encryption-key --key "an example of an encryption key1"
   

2. Reference the secret in the cipherConfig section of your authconfig.

      ...
      kind: AuthConfig
      spec:
        configs:
        - oauth2:
             oidcAuthorizationCode:
               session:
                 cipherConfig:
                   keyRef:
                     name: my-encryption-key
                     namespace: gloo-system
                   cookie:
                     keyPrefix: "my_cookie_prefix"
      

Sessions in Redis

By default, the tokens will be saved in a secure client side cookie. Gloo can instead use Redis to save the OIDC tokens, and set a randomly generated session id in the user’s cookie. Going forward in the Gloo Edge documentation, we will be using examples of OIDC using a redis session.

Example configuration:

apiVersion: enterprise.gloo.solo.io/v1
kind: AuthConfig
metadata:
  name: oidc-dex
  namespace: gloo-system
spec:
  configs:
  - oauth2:
      oidcAuthorizationCode:
        appUrl: http://localhost:8080/
        callbackPath: /callback
        clientId: gloo
        clientSecretRef:
          name: oauth
          namespace: gloo-system
        issuerUrl: http://dex.gloo-system.svc.cluster.local:32000/
        scopes:
        - email
        session:
          failOnFetchFailure: true
          redis:
            cookieName: session
            options:
              host: redis.gloo-system.svc.cluster.local:6379

Forwarding the ID token upstream

You can configure gloo to forward the id token to the upstream on successful authentication. To do that, set the headers section in the configuration.

Example configuration:

apiVersion: enterprise.gloo.solo.io/v1
kind: AuthConfig
metadata:
  name: oidc-dex
  namespace: gloo-system
spec:
  configs:
  - oauth2:
      oidcAuthorizationCode:
        appUrl: http://localhost:8080/
        callbackPath: /callback
        clientId: gloo
        clientSecretRef:
          name: oauth
          namespace: gloo-system
        issuerUrl: http://dex.gloo-system.svc.cluster.local:32000/
        scopes:
        - email
        headers:
          idTokenHeader: "x-token"

Proof Key for Code Exchange (PKCE) for public and untrusted clients

In a traditional OAuth Authorization flow, the client sends a client secret to the authorization server to request an access token. Depending on the type of client that you use, the client secret might be shared across users and devices. Public clients, such as a mobile app, cannot securely store the client secret as it is embedded in the web browser or can be retrieved by decompiling the app. To avoid authorization code injection attacks, you can leverage the Proof Key for Code Exchange (PKCE) OAuth extension.

PKCE builds on top of the OAuth2 protocol. Instead of sending a client secret to the authorization server, the client generates a random value that is called the Code Verifier and hashes the Code Verifier to create the Code Challenge. The Code Challenge is sent to the authorization server where it is stored for later verification. At the same time, the authorization server returns an authorization code that is good for one use. To request an access token, the client now sends the authorization code and the Code Verifier that was generated earlier. The authorization server hashes the Code Verifier and compares the result to the Code Challenge that the client sent earlier. If both values match, the client is authorized and an access token is returned.

With Gloo Edge, you can implement PKCE-secured OAuth flows by leveraging the authEndpointQueryParams and tokenEndpointQueryParams fields in the AuthConfig. For example, to send the code challenge, add the code_challenge query parameter to the authEndpointQueryParams field. To request an access token, include the code and code_verifier in the tokenEndpointQueryParams field.

For more information, see the Auth0 docs.

Examples

We have seen how a sample OIDC AuthConfig is structured. For complete examples of how to set up an OIDC flow with Gloo Edge, check out the following guides:

• Authenticate with Auth0: Integrating Gloo Edge and Auth0 for identity management

• Authenticate with Google: Setup OpenID Connect (OIDC) authentication with the Google identity provider.

• Authenticate with Okta: Integrating Gloo Edge and Okta Identity Cloud

• Authenticate with Dex: Integrating Gloo Edge and Dex Identity Provider

• Authenticate with an Access Token: Integrating Gloo Edge and Access Tokens