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Security configuration for Knative Kafka channels

Configuring TLS authentication for Kafka channels

Transport Layer Security (TLS) is used by Apache Kafka clients and servers to encrypt traffic between Knative and Kafka, as well as for authentication. TLS is the only supported method of traffic encryption for Knative Kafka.

Prerequisites

  • You have cluster or dedicated administrator permissions on OpenShift Container Platform.

  • The OpenShift Serverless Operator, Knative Eventing, and the KnativeKafka CR are installed on your OpenShift Container Platform cluster.

  • You have created a project or have access to a project with the appropriate roles and permissions to create applications and other workloads in OpenShift Container Platform.

  • You have a Kafka cluster CA certificate stored as a .pem file.

  • You have a Kafka cluster client certificate and a key stored as .pem files.

  • Install the OpenShift CLI (oc).

Procedure

  1. Create the certificate files as secrets in your chosen namespace:

    $ oc create secret -n <namespace> generic <kafka_auth_secret> \
  --from-file=ca.crt=caroot.pem \
  --from-file=user.crt=certificate.pem \
  --from-file=user.key=key.pem

    Use the key names ca.crt, user.crt, and user.key. Do not change them.

  2. Start editing the KnativeKafka custom resource:

    $ oc edit knativekafka

  3. Reference your secret and the namespace of the secret:

    apiVersion: operator.serverless.openshift.io/v1alpha1
kind: KnativeKafka
metadata:
  namespace: knative-eventing
  name: knative-kafka
spec:
  channel:
    authSecretName: <kafka_auth_secret>
    authSecretNamespace: <kafka_auth_secret_namespace>
    bootstrapServers: <bootstrap_servers>
    enabled: true
  source:
    enabled: true

    Make sure to specify the matching port in the bootstrap server.

    For example:

    apiVersion: operator.serverless.openshift.io/v1alpha1
kind: KnativeKafka
metadata:
  namespace: knative-eventing
  name: knative-kafka
spec:
  channel:
    authSecretName: tls-user
    authSecretNamespace: kafka
    bootstrapServers: eventing-kafka-bootstrap.kafka.svc:9094
    enabled: true
  source:
    enabled: true

Configuring SASL authentication for Kafka channels

Simple Authentication and Security Layer (SASL) is used by Apache Kafka for authentication. If you use SASL authentication on your cluster, users must provide credentials to Knative for communicating with the Kafka cluster; otherwise events cannot be produced or consumed.

Prerequisites

  • You have cluster or dedicated administrator permissions on OpenShift Container Platform.

  • The OpenShift Serverless Operator, Knative Eventing, and the KnativeKafka CR are installed on your OpenShift Container Platform cluster.

  • You have created a project or have access to a project with the appropriate roles and permissions to create applications and other workloads in OpenShift Container Platform.

  • You have a username and password for a Kafka cluster.

  • You have chosen the SASL mechanism to use, for example, PLAIN, SCRAM-SHA-256, or SCRAM-SHA-512.

  • If TLS is enabled, you also need the ca.crt certificate file for the Kafka cluster.

  • Install the OpenShift CLI (oc).

Procedure

  1. Create the certificate files as secrets in your chosen namespace:

    $ oc create secret -n <namespace> generic <kafka_auth_secret> \
  --from-file=ca.crt=caroot.pem \
  --from-literal=password="SecretPassword" \
  --from-literal=saslType="SCRAM-SHA-512" \
  --from-literal=user="my-sasl-user"

    • Use the key names ca.crt, password, and sasl.mechanism. Do not change them.

    • If you want to use SASL with public CA certificates, you must use the tls.enabled=true flag, rather than the ca.crt argument, when creating the secret. For example:

      $ oc create secret -n <namespace> generic <kafka_auth_secret> \
  --from-literal=tls.enabled=true \
  --from-literal=password="SecretPassword" \
  --from-literal=saslType="SCRAM-SHA-512" \
  --from-literal=user="my-sasl-user"

  2. Start editing the KnativeKafka custom resource:

    $ oc edit knativekafka

  3. Reference your secret and the namespace of the secret:

    apiVersion: operator.serverless.openshift.io/v1alpha1
kind: KnativeKafka
metadata:
  namespace: knative-eventing
  name: knative-kafka
spec:
  channel:
    authSecretName: <kafka_auth_secret>
    authSecretNamespace: <kafka_auth_secret_namespace>
    bootstrapServers: <bootstrap_servers>
    enabled: true
  source:
    enabled: true

    Make sure to specify the matching port in the bootstrap server.

    For example:

    apiVersion: operator.serverless.openshift.io/v1alpha1
kind: KnativeKafka
metadata:
  namespace: knative-eventing
  name: knative-kafka
spec:
  channel:
    authSecretName: scram-user
    authSecretNamespace: kafka
    bootstrapServers: eventing-kafka-bootstrap.kafka.svc:9093
    enabled: true
  source:
    enabled: true