15.4. Using OAuth 2.0 token-based authentication

1. The Kafka client requests an access token from the authorization server using a client ID and secret, and optionally a refresh token. Alternatively, the client may authenticate using a username and a password.
2. The authorization server generates a new access token.
3. The Kafka client authenticates with the Kafka broker using the SASL OAUTHBEARER mechanism to pass the access token.
4. The Kafka broker validates the access token by calling a token introspection endpoint on the authorization server using its own client ID and secret.
5. A Kafka client session is established if the token is valid.

1. The Kafka client authenticates with the authorization server from the token endpoint, using a client ID and secret, and optionally a refresh token. Alternatively, the client may authenticate using a username and a password.
2. The authorization server generates a new access token.
3. The Kafka client authenticates with the Kafka broker using the SASL OAUTHBEARER mechanism to pass the access token.
4. The Kafka broker validates the access token locally using a JWT token signature check, and local token introspection.

1. The Kafka client authenticates with the Kafka broker using the SASL OAUTHBEARER mechanism to pass the long-lived access token.
2. The Kafka broker validates the access token by calling a token introspection endpoint on the authorization server, using its own client ID and secret.
3. A Kafka client session is established if the token is valid.

1. The Kafka client authenticates with the Kafka broker using the SASL OAUTHBEARER mechanism to pass the long-lived access token.
2. The Kafka broker validates the access token locally using a JWT token signature check and local token introspection.

1. The Kafka client passes a clientId as a username and a secret as a password.
2. The Kafka broker uses a token endpoint to pass the clientId and secret to the authorization server.
3. The authorization server returns a fresh access token or an error if the client credentials are not valid.

4. The Kafka broker validates the token in one of the following ways:

   1. If a token introspection endpoint is specified, the Kafka broker validates the access token by calling the endpoint on the authorization server. A session is established if the token validation is successful.
   2. If local token introspection is used, a request is not made to the authorization server. The Kafka broker validates the access token locally using a JWT token signature check.

1. The Kafka client passes a username and password. The password provides the value of an access token that was obtained manually and configured before running the client.

2. The password is passed with or without an $accessToken: string prefix depending on whether or not the Kafka broker listener is configured with a token endpoint for authentication.

   1. If the token endpoint is configured, the password should be prefixed by $accessToken: to let the broker know that the password parameter contains an access token rather than a client secret. The Kafka broker interprets the username as the account username.
   2. If the token endpoint is not configured on the Kafka broker listener (enforcing a no-client-credentials mode), the password should provide the access token without the prefix. The Kafka broker interprets the username as the account username. In this mode, the client doesn’t use a client ID and secret, and the password parameter is always interpreted as a raw access token.

3. The Kafka broker validates the token in one of the following ways:

   1. If a token introspection endpoint is specified, the Kafka broker validates the access token by calling the endpoint on the authorization server. A session is established if token validation is successful.
   2. If local token introspection is used, there is no request made to the authorization server. Kafka broker validates the access token locally using a JWT token signature check.

Procedure

1. Deploy the authorization server to your cluster.

2. Access the CLI or admin console for the authorization server to configure OAuth 2.0 for Streams for Apache Kafka.

   Now prepare the authorization server to work with Streams for Apache Kafka.

3. Configure a kafka-broker client.
4. Configure clients for each Kafka client component of your application.

Procedure

1. Update the Kafka broker configuration (Kafka.spec.kafka) of your Kafka resource in an editor.

   oc edit kafka my-cluster

2. Configure the Kafka broker listeners configuration.

   The configuration for each type of listener does not have to be the same, as they are independent.

   The examples here show the configuration options as configured for external listeners.

   Example 1: Configuring fast local JWT token validation

   #...
   - name: external3
     port: 9094
     type: loadbalancer
     tls: true
     authentication:
       type: oauth 

   1

   
       validIssuerUri: https://<auth_server_address>/auth/realms/external 

   2

   
       jwksEndpointUri: https://<auth_server_address>/auth/realms/external/protocol/openid-connect/certs 

   3

   
       userNameClaim: preferred_username 

   4

   
       maxSecondsWithoutReauthentication: 3600 

   5

   
       tlsTrustedCertificates: 

   6

   
       - secretName: oauth-server-cert
         certificate: ca.crt
       disableTlsHostnameVerification: true 

   7

   
       jwksExpirySeconds: 360 

   8

   
       jwksRefreshSeconds: 300 

   9

   
       jwksMinRefreshPauseSeconds: 1 

   10

   1

   Listener type set to oauth.

   2

   URI of the token issuer used for authentication.

   3

   URI of the JWKS certificate endpoint used for local JWT validation.

   4

   The token claim (or key) that contains the actual username used to identify the user. Its value depends on the authorization server. If necessary, a JsonPath expression like "['user.info'].['user.id']" can be used to retrieve the username from nested JSON attributes within a token.

   5

   (Optional) Activates the Kafka re-authentication mechanism that enforces session expiry to the same length of time as the access token. If the specified value is less than the time left for the access token to expire, then the client will have to re-authenticate before the actual token expiry. By default, the session does not expire when the access token expires, and the client does not attempt re-authentication.

   6

   (Optional) Trusted certificates for TLS connection to the authorization server.

   7

   (Optional) Disable TLS hostname verification. Default is false.

   8

   The duration the JWKS certificates are considered valid before they expire. Default is 360 seconds. If you specify a longer time, consider the risk of allowing access to revoked certificates.

   9

   The period between refreshes of JWKS certificates. The interval must be at least 60 seconds shorter than the expiry interval. Default is 300 seconds.

   10

   The minimum pause in seconds between consecutive attempts to refresh JWKS public keys. When an unknown signing key is encountered, the JWKS keys refresh is scheduled outside the regular periodic schedule with at least the specified pause since the last refresh attempt. The refreshing of keys follows the rule of exponential backoff, retrying on unsuccessful refreshes with ever increasing pause, until it reaches jwksRefreshSeconds. The default value is 1.

   Example 2: Configuring token validation using an introspection endpoint

   - name: external3
     port: 9094
     type: loadbalancer
     tls: true
     authentication:
       type: oauth
       validIssuerUri: https://<auth_server_address>/auth/realms/external
       introspectionEndpointUri: https://<auth_server_address>/auth/realms/external/protocol/openid-connect/token/introspect 

   1

   
       clientId: kafka-broker 

   2

   
       clientSecret: 

   3

   
         secretName: my-cluster-oauth
         key: clientSecret
       userNameClaim: preferred_username 

   4

   
       maxSecondsWithoutReauthentication: 3600 

   5

   1

   URI of the token introspection endpoint.

   2

   Client ID to identify the client.

   3

   Client Secret and client ID is used for authentication.

   4

   The token claim (or key) that contains the actual username used to identify the user. Its value depends on the authorization server. If necessary, a JsonPath expression like "['user.info'].['user.id']" can be used to retrieve the username from nested JSON attributes within a token.

   5

   (Optional) Activates the Kafka re-authentication mechanism that enforces session expiry to the same length of time as the access token. If the specified value is less than the time left for the access token to expire, then the client will have to re-authenticate before the actual token expiry. By default, the session does not expire when the access token expires, and the client does not attempt re-authentication.

   Depending on how you apply OAuth 2.0 authentication, and the type of authorization server, there are additional (optional) configuration settings you can use:

     # ...
     authentication:
       type: oauth
       # ...
       checkIssuer: false 

   1

   
       checkAudience: true 

   2

   
       fallbackUserNameClaim: client_id 

   3

   
       fallbackUserNamePrefix: client-account- 

   4

   
       validTokenType: bearer 

   5

   
       userInfoEndpointUri: https://<auth_server_address>/auth/realms/external/protocol/openid-connect/userinfo 

   6

   
       enableOauthBearer: false 

   7

   
       enablePlain: true 

   8

   
       tokenEndpointUri: https://<auth_server_address>/auth/realms/external/protocol/openid-connect/token 

   9

   
       customClaimCheck: "@.custom == 'custom-value'" 

   10

   
       clientAudience: audience 

   11

   
       clientScope: scope 

   12

   
       connectTimeoutSeconds: 60 

   13

   
       readTimeoutSeconds: 60 

   14

   
       httpRetries: 2 

   15

   
       httpRetryPauseMs: 300 

   16

   
       groupsClaim: "$.groups" 

   17

   
       groupsClaimDelimiter: "," 

   18

   
       includeAcceptHeader: false 

   19

   1

   If your authorization server does not provide an iss claim, it is not possible to perform an issuer check. In this situation, set checkIssuer to false and do not specify a validIssuerUri. Default is true.

   2

   If your authorization server provides an aud (audience) claim, and you want to enforce an audience check, set checkAudience to true. Audience checks identify the intended recipients of tokens. As a result, the Kafka broker will reject tokens that do not have its clientId in their aud claim. Default is false.

   3

   An authorization server may not provide a single attribute to identify both regular users and clients. When a client authenticates in its own name, the server might provide a client ID. When a user authenticates using a username and password to obtain a refresh token or an access token, the server might provide a username attribute in addition to a client ID. Use this fallback option to specify the username claim (attribute) to use if a primary user ID attribute is not available. If necessary, a JsonPath expression like "['client.info'].['client.id']" can be used to retrieve the fallback username to retrieve the username from nested JSON attributes within a token.

   4

   In situations where fallbackUserNameClaim is applicable, it may also be necessary to prevent name collisions between the values of the username claim, and those of the fallback username claim. Consider a situation where a client called producer exists, but also a regular user called producer exists. In order to differentiate between the two, you can use this property to add a prefix to the user ID of the client.

   5

   (Only applicable when using introspectionEndpointUri) Depending on the authorization server you are using, the introspection endpoint may or may not return the token type attribute, or it may contain different values. You can specify a valid token type value that the response from the introspection endpoint has to contain.

   6

   (Only applicable when using introspectionEndpointUri) The authorization server may be configured or implemented in such a way to not provide any identifiable information in an Introspection Endpoint response. In order to obtain the user ID, you can configure the URI of the userinfo endpoint as a fallback. The userNameClaim, fallbackUserNameClaim, and fallbackUserNamePrefix settings are applied to the response of userinfo endpoint.

   7

   Set this to false to disable the OAUTHBEARER mechanism on the listener. At least one of PLAIN or OAUTHBEARER has to be enabled. Default is true.

   8

   Set to true to enable PLAIN authentication on the listener, which is supported for clients on all platforms.

   9

   Additional configuration for the PLAIN mechanism. If specified, clients can authenticate over PLAIN by passing an access token as the password using an $accessToken: prefix. For production, always use https:// urls.

   10

   Additional custom rules can be imposed on the JWT access token during validation by setting this to a JsonPath filter query. If the access token does not contain the necessary data, it is rejected. When using the introspectionEndpointUri, the custom check is applied to the introspection endpoint response JSON.

   11

   An audience parameter passed to the token endpoint. An audience is used when obtaining an access token for inter-broker authentication. It is also used in the name of a client for OAuth 2.0 over PLAIN client authentication using a clientId and secret. This only affects the ability to obtain the token, and the content of the token, depending on the authorization server. It does not affect token validation rules by the listener.

   12

   A scope parameter passed to the token endpoint. A scope is used when obtaining an access token for inter-broker authentication. It is also used in the name of a client for OAuth 2.0 over PLAIN client authentication using a clientId and secret. This only affects the ability to obtain the token, and the content of the token, depending on the authorization server. It does not affect token validation rules by the listener.

   13

   The connect timeout in seconds when connecting to the authorization server. The default value is 60.

   14

   The read timeout in seconds when connecting to the authorization server. The default value is 60.

   15

   The maximum number of times to retry a failed HTTP request to the authorization server. The default value is 0, meaning that no retries are performed. To use this option effectively, consider reducing the timeout times for the connectTimeoutSeconds and readTimeoutSeconds options. However, note that retries may prevent the current worker thread from being available to other requests, and if too many requests stall, it could make the Kafka broker unresponsive.

   16

   The time to wait before attempting another retry of a failed HTTP request to the authorization server. By default, this time is set to zero, meaning that no pause is applied. This is because many issues that cause failed requests are per-request network glitches or proxy issues that can be resolved quickly. However, if your authorization server is under stress or experiencing high traffic, you may want to set this option to a value of 100 ms or more to reduce the load on the server and increase the likelihood of successful retries.

   17

   A JsonPath query that is used to extract groups information from either the JWT token or the introspection endpoint response. This option is not set by default. By configuring this option, a custom authorizer can make authorization decisions based on user groups.

   18

   A delimiter used to parse groups information when it is returned as a single delimited string. The default value is ',' (comma).

   19

   Some authorization servers have issues with client sending Accept: application/json header. By setting includeAcceptHeader: false the header will not be sent. Default is true.

3. Save and exit the editor, then wait for rolling updates to complete.

4. Check the update in the logs or by watching the pod state transitions:

   oc logs -f ${POD_NAME} -c ${CONTAINER_NAME}
   oc get pod -w

   The rolling update configures the brokers to use OAuth 2.0 authentication.

Procedure

1. Add the client library with OAuth 2.0 support to the pom.xml file for the Kafka client:

   <dependency>
    <groupId>io.strimzi</groupId>
    <artifactId>kafka-oauth-client</artifactId>
    <version>0.15.0.redhat-00007</version>
   </dependency>

2. Configure the client properties by specifying the following configuration in a properties file:

   • The security protocol
   • The SASL mechanism

   • The JAAS module and authentication properties according to the method being used

     For example, we can add the following to a client.properties file:

     Client credentials mechanism properties

     security.protocol=SASL_SSL 

     1

     
     sasl.mechanism=OAUTHBEARER 

     2

     
     ssl.truststore.location=/tmp/truststore.p12 

     3

     
     ssl.truststore.password=$STOREPASS
     ssl.truststore.type=PKCS12
     sasl.jaas.config=org.apache.kafka.common.security.oauthbearer.OAuthBearerLoginModule required \
       oauth.token.endpoint.uri="<token_endpoint_url>" \ 

     4

     
       oauth.client.id="<client_id>" \ 

     5

     
       oauth.client.secret="<client_secret>" \ 

     6

     
       oauth.ssl.truststore.location="/tmp/oauth-truststore.p12" \ 

     7

     
       oauth.ssl.truststore.password="$STOREPASS" \ 

     8

     
       oauth.ssl.truststore.type="PKCS12" \ 

     9

     
       oauth.scope="<scope>" \ 

     10

     
       oauth.audience="<audience>" ; 

     11

     
     sasl.login.callback.handler.class=io.strimzi.kafka.oauth.client.JaasClientOauthLoginCallbackHandler

     1

     SASL_SSL security protocol for TLS-encrypted connections. Use SASL_PLAINTEXT over unencrypted connections for local development only.

     2

     The SASL mechanism specified as OAUTHBEARER or PLAIN.

     3

     The truststore configuration for secure access to the Kafka cluster.

     4

     URI of the authorization server token endpoint.

     5

     Client ID, which is the name used when creating the client in the authorization server.

     6

     Client secret created when creating the client in the authorization server.

     7

     The location contains the public key certificate (truststore.p12) for the authorization server.

     8

     The password for accessing the truststore.

     9

     The truststore type.

     10

     (Optional) The scope for requesting the token from the token endpoint. An authorization server may require a client to specify the scope.

     11

     (Optional) The audience for requesting the token from the token endpoint. An authorization server may require a client to specify the audience.

     Password grants mechanism properties

     security.protocol=SASL_SSL
     sasl.mechanism=OAUTHBEARER
     ssl.truststore.location=/tmp/truststore.p12
     ssl.truststore.password=$STOREPASS
     ssl.truststore.type=PKCS12
     sasl.jaas.config=org.apache.kafka.common.security.oauthbearer.OAuthBearerLoginModule required \
       oauth.token.endpoint.uri="<token_endpoint_url>" \
       oauth.client.id="<client_id>" \ 

     1

     
       oauth.client.secret="<client_secret>" \ 

     2

     
       oauth.password.grant.username="<username>" \ 

     3

     
       oauth.password.grant.password="<password>" \ 

     4

     
       oauth.ssl.truststore.location="/tmp/oauth-truststore.p12" \
       oauth.ssl.truststore.password="$STOREPASS" \
       oauth.ssl.truststore.type="PKCS12" \
       oauth.scope="<scope>" \
       oauth.audience="<audience>" ;
     sasl.login.callback.handler.class=io.strimzi.kafka.oauth.client.JaasClientOauthLoginCallbackHandler

     1

     Client ID, which is the name used when creating the client in the authorization server.

     2

     (Optional) Client secret created when creating the client in the authorization server.

     3

     Username for password grant authentication. OAuth password grant configuration (username and password) uses the OAuth 2.0 password grant method. To use password grants, create a user account for a client on your authorization server with limited permissions. The account should act like a service account. Use in environments where user accounts are required for authentication, but consider using a refresh token first.

     4

     Password for password grant authentication.

     注記

     SASL PLAIN does not support passing a username and password (password grants) using the OAuth 2.0 password grant method.

     Access token properties

     security.protocol=SASL_SSL
     sasl.mechanism=OAUTHBEARER
     ssl.truststore.location=/tmp/truststore.p12
     ssl.truststore.password=$STOREPASS
     ssl.truststore.type=PKCS12
     sasl.jaas.config=org.apache.kafka.common.security.oauthbearer.OAuthBearerLoginModule required \
       oauth.token.endpoint.uri="<token_endpoint_url>" \
       oauth.access.token="<access_token>" \ 

     1

     
       oauth.ssl.truststore.location="/tmp/oauth-truststore.p12" \
       oauth.ssl.truststore.password="$STOREPASS" \
       oauth.ssl.truststore.type="PKCS12" ;
     sasl.login.callback.handler.class=io.strimzi.kafka.oauth.client.JaasClientOauthLoginCallbackHandler

     1

     Long-lived access token for Kafka clients.

     Refresh token properties

     security.protocol=SASL_SSL
     sasl.mechanism=OAUTHBEARER
     ssl.truststore.location=/tmp/truststore.p12
     ssl.truststore.password=$STOREPASS
     ssl.truststore.type=PKCS12
     sasl.jaas.config=org.apache.kafka.common.security.oauthbearer.OAuthBearerLoginModule required \
       oauth.token.endpoint.uri="<token_endpoint_url>" \
       oauth.client.id="<client_id>" \ 

     1

     
       oauth.client.secret="<client_secret>" \ 

     2

     
       oauth.refresh.token="<refresh_token>" \ 

     3

     
       oauth.ssl.truststore.location="/tmp/oauth-truststore.p12" \
       oauth.ssl.truststore.password="$STOREPASS" \
       oauth.ssl.truststore.type="PKCS12" ;
     sasl.login.callback.handler.class=io.strimzi.kafka.oauth.client.JaasClientOauthLoginCallbackHandler

     1

     Client ID, which is the name used when creating the client in the authorization server.

     2

     (Optional) Client secret created when creating the client in the authorization server.

     3

     Long-lived refresh token for Kafka clients.

3. Input the client properties for OAUTH 2.0 authentication into the Java client code.

   Example showing input of client properties

   Properties props = new Properties();
   try (FileReader reader = new FileReader("client.properties", StandardCharsets.UTF_8)) {
     props.load(reader);
   }

4. Verify that the Kafka client can access the Kafka brokers.

Procedure

1. Create a client secret and mount it to the component as an environment variable.

   For example, here we are creating a client Secret for the Kafka Bridge:

   apiVersion: kafka.strimzi.io/v1beta2
   kind: Secret
   metadata:
    name: my-bridge-oauth
   type: Opaque
   data:
    clientSecret: MGQ1OTRmMzYtZTllZS00MDY2LWI5OGEtMTM5MzM2NjdlZjQw 

   1

   1

   The clientSecret key must be in base64 format.

2. Create or edit the resource for the Kafka component so that OAuth 2.0 authentication is configured for the authentication property.

   For OAuth 2.0 authentication, you can use the following options:

   • Client ID and secret
   • Client ID and refresh token
   • Access token
   • Username and password
   • TLS

   For example, here OAuth 2.0 is assigned to the Kafka Bridge client using a client ID and secret, and TLS:

   apiVersion: kafka.strimzi.io/v1beta2
   kind: KafkaBridge
   metadata:
     name: my-bridge
   spec:
     # ...
     authentication:
       type: oauth 

   1

   
       tokenEndpointUri: https://<auth-server-address>/auth/realms/master/protocol/openid-connect/token 

   2

   
       clientId: kafka-bridge
       clientSecret:
         secretName: my-bridge-oauth
         key: clientSecret
       tlsTrustedCertificates: 

   3

   
       - secretName: oauth-server-cert
         certificate: tls.crt

   1

   Authentication type set to oauth.

   2

   URI of the token endpoint for authentication.

   3

   Trusted certificates for TLS connection to the authorization server.

   Depending on how you apply OAuth 2.0 authentication, and the type of authorization server, there are additional configuration options you can use:

   # ...
   spec:
     # ...
     authentication:
       # ...
       disableTlsHostnameVerification: true 

   1

   
       checkAccessTokenType: false 

   2

   
       accessTokenIsJwt: false 

   3

   
       scope: any 

   4

   
       audience: kafka 

   5

   
       connectTimeoutSeconds: 60 

   6

   
       readTimeoutSeconds: 60 

   7

   
       httpRetries: 2 

   8

   
       httpRetryPauseMs: 300 

   9

   
       includeAcceptHeader: false 

   10

   1

   (Optional) Disable TLS hostname verification. Default is false.

   2

   If the authorization server does not return a typ (type) claim inside the JWT token, you can apply checkAccessTokenType: false to skip the token type check. Default is true.

   3

   If you are using opaque tokens, you can apply accessTokenIsJwt: false so that access tokens are not treated as JWT tokens.

   4

   (Optional) The scope for requesting the token from the token endpoint. An authorization server may require a client to specify the scope. In this case it is any.

   5

   (Optional) The audience for requesting the token from the token endpoint. An authorization server may require a client to specify the audience. In this case it is kafka.

   6

   (Optional) The connect timeout in seconds when connecting to the authorization server. The default value is 60.

   7

   (Optional) The read timeout in seconds when connecting to the authorization server. The default value is 60.

   8

   (Optional) The maximum number of times to retry a failed HTTP request to the authorization server. The default value is 0, meaning that no retries are performed. To use this option effectively, consider reducing the timeout times for the connectTimeoutSeconds and readTimeoutSeconds options. However, note that retries may prevent the current worker thread from being available to other requests, and if too many requests stall, it could make the Kafka broker unresponsive.

   9

   (Optional) The time to wait before attempting another retry of a failed HTTP request to the authorization server. By default, this time is set to zero, meaning that no pause is applied. This is because many issues that cause failed requests are per-request network glitches or proxy issues that can be resolved quickly. However, if your authorization server is under stress or experiencing high traffic, you may want to set this option to a value of 100 ms or more to reduce the load on the server and increase the likelihood of successful retries.

   10

   (Optional) Some authorization servers have issues with client sending Accept: application/json header. By setting includeAcceptHeader: false the header will not be sent. Default is true.

3. Apply the changes to the deployment of your Kafka resource.

   oc apply -f your-file

4. Check the update in the logs or by watching the pod state transitions:

   oc logs -f ${POD_NAME} -c ${CONTAINER_NAME}
   oc get pod -w

   The rolling updates configure the component for interaction with Kafka brokers using OAuth 2.0 authentication.