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OAuth for CFK with Azure

Confluent Platform 7.7 and CFK 2.9.0 released OAuth support. This repository sets up a basic CP cluster via CFK running on Azure Kubernetes Service (AKS) enforcing external clients to use OAuth for authentication with Azure AD (Entra ID) as the identity provider.

In technical detail it deploys:

  • 1 KraftController
  • 3 Kafka brokers
  • 1 Producer application (client)
  • 1 Control Center

General resources:

Note

This repositry only focusses on Confluent Platform, not Confluent Cloud. For an example for OAuth with Confluent Cloud check out https://github.com/pneff93/ccloud-clients-oauth.

Azure AD endpoints

For the later configuration we need to set the token_endpoint, the jwks_uri, and the issuer. We can obtain all information via

curl https://login.microsoftonline.com/<tenant-id>/v2.0/.well-known/openid-configuration | jq

Generally, those are

token_endpoint = https://login.microsoftonline.com/<tenant-id>/oauth2/v2.0/token
jwks_uri = https://login.microsoftonline.com/<tenant-id>/discovery/v2.0/keys
issuer = https://login.microsoftonline.com/<tenant-id>/v2.0

Azure AD applications

To retrieve the JWT token, CP is using the client credentials grant flow. So, we need to register an application in Azure AD and create a secret. We can get a JWT token via:

curl -X POST -H "Content-Type: application/x-www-form-urlencoded" \
-d 'client_id=[client_id]&client_secret=[client_secret value]&grant_type=client_credentials' \
https://login.microsoftonline.com/[tenant_id]/oauth2/token

Note

In this example, we only register one application in Azure AD. Consider different applications with its secret per CP component and client.

CFK cluster

Store the clientId and secret in a file and deploy it as a k8s secret.

kubectl create -n confluent secret generic oauth-jass --from-file=oauth.txt=client-credentials.txt

Afterwards, we configure the Kafka CR

listeners:
  external:
    authentication:
      type: oauth
      jaasConfig:
        secretRef: oauth-jass
      oauthSettings:
        groupsClaimName: groups
        subClaimName: sub
        audience: <client-id>
        expectedIssuer: see above
        jwksEndpointUri: see above
        tokenEndpointUri: see above
configOverrides:
  server:
    - listener.name.external.oauthbearer.sasl.server.callback.handler.class=org.apache.kafka.common.security.oauthbearer.secured.OAuthBearerValidatorCallbackHandler
    - listener.name.external.oauthbearer.sasl.jaas.config=org.apache.kafka.common.security.oauthbearer.OAuthBearerLoginModule required;

Once the confluent-operator is running, we deploy the cluster with

kubectl apply -f ./cluster.yaml -n confluent

Producer Application

We develop a simple producer application producing events in a for loop. We set the configuration to:

settings.setProperty(CommonClientConfigs.SECURITY_PROTOCOL_CONFIG, "SASL_PLAINTEXT")
settings.setProperty(SaslConfigs.SASL_MECHANISM, "OAUTHBEARER")
settings.setProperty(SaslConfigs.SASL_LOGIN_CONNECT_TIMEOUT_MS, "15000")
settings.setProperty(SaslConfigs.SASL_OAUTHBEARER_TOKEN_ENDPOINT_URL, "https://login.microsoftonline.com/<tenant-id>/oauth2/v2.0/token")
settings.setProperty(SaslConfigs.SASL_LOGIN_CALLBACK_HANDLER_CLASS, "org.apache.kafka.common.security.oauthbearer.secured.OAuthBearerLoginCallbackHandler")
settings.setProperty(SaslConfigs.SASL_JAAS_CONFIG, "org.apache.kafka.common.security.oauthbearer.OAuthBearerLoginModule required clientId='<client-id>' clientSecret='<client-secret' scope='<Azure client id of the broker application>/.default';")

Note, that we need to add the scope to the sasl.jaas.config which is <Azure client id of the broker application>/.default.

Azure Container Registry

To deploy the Producer application in the AKS cluster, we need to build and push an image to the Azure Container Registry (ACR) and integrate it with the AKS cluster.

# Login to Container Registry
az login
az acr login --name <acr-name>

# Attach Container Registry to AKS cluster
az aks update --name <aks-name> --resource-group <rg-group> --attach-acr <aks-name>

# Check if the attachment was successful
az aks check-acr --resource-group <rg-group> --name <aks-name> --acr <aks-name>.azurecr.io

Deploy Producer application

We build the image via

# Build fatJar 
./gradlew fatJar

# Build image (fatJar needs to be located in main folder)
docker build -t kafkaproducer .

# Tag the built image
docker tag kafkaproducer <aks-name>.azurecr.io/kafkaproducer:0.1.0

# Push the image to the registry via 
docker push <aks-name>.azurecr.io/kafkaproducer:0.1.0

Deploy the Kafka Producer via

kubectl apply -f ./KafkaProducer/Deployment.yaml -n confluent

If everything runs successfully we should obtain similar logs

16:44:18.015 [Thread-0] INFO  org.apache.kafka.common.security.oauthbearer.internals.expiring.ExpiringCredentialRefreshingLogin - Successfully logged in.
16:44:18.042 [kafka-expiring-relogin-thread-4113761a-d187-402f-a48a-8ae0e86f78dd] INFO  org.apache.kafka.common.security.oauthbearer.internals.expiring.ExpiringCredentialRefreshingLogin - [Principal=:4113761a-d187-402f-a48a-8ae0e86f78dd]: Expiring credential re-login thread started.
16:44:18.042 [kafka-expiring-relogin-thread-4113761a-d187-402f-a48a-8ae0e86f78dd] INFO  org.apache.kafka.common.security.oauthbearer.internals.expiring.ExpiringCredentialRefreshingLogin - [Principal=4113761a-d187-402f-a48a-8ae0e86f78dd]: Expiring credential valid from 2024-08-18T16:39:17.000+0000 to 2024-08-18T17:44:17.000+0000
16:44:18.042 [kafka-expiring-relogin-thread-4113761a-d187-402f-a48a-8ae0e86f78dd] INFO  org.apache.kafka.common.security.oauthbearer.internals.expiring.ExpiringCredentialRefreshingLogin - [Principal=:4113761a-d187-402f-a48a-8ae0e86f78dd]: Expiring credential re-login sleeping until: 2024-08-18T17:34:15.583+0000
16:44:18.066 [Thread-0] INFO  org.apache.kafka.common.utils.AppInfoParser - Kafka version: 3.7.0
16:44:18.067 [Thread-0] INFO  org.apache.kafka.common.utils.AppInfoParser - Kafka commitId: 2ae524ed625438c5
16:44:18.067 [Thread-0] INFO  org.apache.kafka.common.utils.AppInfoParser - Kafka startTimeMs: 1723999458064
16:44:18.326 [kafka-producer-network-thread | producer-1] INFO  org.apache.kafka.clients.Metadata - [Producer clientId=producer-1] Cluster ID: 3b658def-2b27-4765-b0a
16:44:18.440 [kafka-producer-network-thread | producer-1] INFO  org.apache.kafka.clients.producer.internals.TransactionManager - [Producer clientId=producer-1] ProducerId set to 3000 with epoch 0
16:44:28.071 [Thread-0] INFO  KafkaProducer - Kafka Producer started
16:44:28.115 [kafka-producer-network-thread | producer-1] INFO  KafkaProducer - event produced to test-topic

Control Center

Finally, we would like to see the produced events also in C3. We need to add OAuth configurations as well to authenticate to the Kafka brokers.

dependencies:
  kafka:
    bootstrapEndpoint: broker.confluent.svc.cluster.local:9092
    authentication:
      type: oauth
      jaasConfig:
        secretRef: oauth-jass
      oauthSettings:
        tokenEndpointUri: see above
        scope: <Azure client id of the broker application>/.default>
# Update cluster
kubectl apply -f ./cluster.yaml -n confluent

# Port forward C3
kubectl port-forward controlcenter-0 9021:9021

We access C3 via localhost:9021 and see the produced events: