Managing access

You can secure your Event Streams resources by managing the access each user and application has to each resource.

An Event Streams cluster can be configured to expose up to 2 internal and 1 external Kafka listeners. These listeners provide the mechanism for Kafka client applications to communicate with the Kafka brokers. The bootstrap address is used for the initial connection to the cluster. The address will resolve to one of the brokers in the cluster and respond with metadata describing all the relevant connection information for the remaining brokers.

Each Kafka listener providing a connection to Event Streams can be configured to authenticate connections with either Mutual TLS or SCRAM SHA 512 authentication mechanisms.

Additionally, the Event Streams cluster can be configured to authorize operations sent via an authenticated listener.

Note: Schemas in the Event Streams schema registry are a special case and are secured using the resource type of topic combined with a prefix of __schema_. You can control the ability of users and applications to create, delete, read, and update schemas.

Accessing the Event Streams UI and CLI

When Kafka authentication is enabled, the Event Streams UI requires you to log in by using an IBM Cloud Pak foundational services Identity and Access Management (IAM) user. Access to the Event Streams CLI always requires a user to be supplied to the cloudctl login command, so the CLI is not affected by enabling Kafka authentication.

The default cluster administrator (admin) IAM user credentials are stored in a secret within the ibm-common-services namespace. To retrieve the username and password:

1. Log in to your Red Hat OpenShift Container Platform as a cluster administrator by using the oc CLI (oc login).
2. Extract and decode the current IBM Cloud Pak foundational services admin username:
   oc --namespace ibm-common-services get secret platform-auth-idp-credentials -o jsonpath='{.data.admin_username}' | base64 --decode
3. Extract and decode the current IBM Cloud Pak foundational services admin password:
   oc --namespace ibm-common-services get secret platform-auth-idp-credentials -o jsonpath='{.data.admin_password}' | base64 --decode

Note: The password is auto-generated in accordance with the default password rules for IBM Cloud Pak foundational services. To change the username or password of the admin user, see the instructions about changing the cluster administrator access credentials.

The admin user has the Cluster Administrator role granting full access to all resources within the cluster, including Event Streams.

Adding additional groups and users

Access for groups and users is managed through IAM teams. If you have not previously created any teams, the admin user credentials can be used to set up a team.

Managing access to the UI and CLI

Access to the Event Streams UI and CLI requires an IAM user with a role of Cluster Administrator or Administrator. The role can be set for the user or for the group the user is part of.

Any groups or users added to an IAM team with the Cluster Administrator role can log in to the Event Streams UI and CLI. Any groups or users with the Adminstrator role will not be able to log in until the namespace that contains the Event Streams cluster is added as a resource for the IAM team.

If Kafka authorization is enabled by setting spec.strimziOverrides.kafka.authorization to type: runas, operations by IAM users are are automatically mapped to a Kafka principal with authorization for the required Kafka resources.

Managing access to Kafka resources

Each Kafka listener exposing an authenticated connection to Event Streams requires credentials to be presented when connecting. Credentials are created by using a KafkaUser custom resource, where the spec.authentication.type field has a value that matches the Kafka listener authentication type.

You can create a KafkaUser by using the Event Streams UI or CLI. It is also possible to create a KafkaUser by using the OpenShift Container Platform UI or CLI, or the underlying Kubernetes API by applying a KafkaUser operand request.

To assist in generating compatible KafkaUser credentials, the Event Streams UI indicates which authentication mechanism is being configured for each Kafka listener.

Warning: Do not use or modify the internal Event Streams KafkaUsers named <cluster>-ibm-es-kafka-user and <cluster>-ibm-es-georep-source-user. These are reserved to be used internally within the Event Streams instance.

Creating a KafkaUser in the Event Streams UI

1. Log in to your Event Streams UI as an administrator from a supported web browser (see how to determine the login URL for your Event Streams UI).
2. Click the Connect to this cluster tile to view the Cluster connection panel.
3. Go to the Kafka listener and Credentials section.
4. To generate credentials for external clients, click External, or to generate credentials for internal clients, click Internal.
5. Click the Generate SCRAM credential or Generate TLS credential button next to the required listener to view the credential generation dialog.
6. Follow the instructions to generate credentials with desired permissions.
   Note: If your cluster does not have authorization enabled, the permission choices will not have any effect.

The generated credential appears after the listener bootstrap address:

• For SCRAM credentials, two tabs are displayed: Username and password and Basic Authentication. The SCRAM username and password combination is used by Kafka applications, while the Basic Authentication credential is for use as an HTTP authorization header.
• For TLS credentials, a download button is displayed, providing a zip archive with the required certificates and keys.

A KafkaUser will be created with the entered credential name.

The cluster truststore is not part of the above credentials zip archive. This certificate is required for all external connections and is available to download from the Cluster connection panel under the Certificates heading. Upon downloading the PKCS12 certificate, the certificate password will also be displayed.

Creating a KafkaUser in the Event Streams CLI

1. Log in to your cluster as an administrator by using the IBM Cloud Pak CLI:
   cloudctl login -a https://<cluster_address>:<cluster_router_https_port>
2. Initialize the Event Streams plugin specifying your namespace and choose your instance from the numbered list:
   cloudctl es init -n <namespace>
3. Use the kafka-user-create command to create a KafkaUser with the accompanying permissions.
   Note: If your cluster does not have authorization enabled, the permission choices will not have any effect.

For example, to create SCRAM credentials with authorization to create topics & schemas and produce (including transactions) & consume from every topic:

cloudctl es kafka-user-create \
  --name my-user \
  --consumer \
  --producer \
  --schema-topic-create \
  --all-topics \
  --all-groups \
  --all-txnids \
  --auth-type scram-sha-512

For information about all options provided by the command, use the --help flag:
cloudctl es kafka-user-create --help

UI and CLI KafkaUser authorization

KafkaUsers created by using the UI and CLI can only be configured with permissions for the most common operations against Kafka resources. You can later modify the created KafkaUser to add additional ACL rules.

Creating a KafkaUser in the UI

Navigate to the Event Streams installed operator menu and select the KafkaUser tab. Click Create KafkaUser. The YAML view contains sample KafkaUser definitions to consume, produce, or modify every resource.

Retrieving credentials

When a KafkaUser custom resource is created, the Entity Operator within Event Streams will create the principal in ZooKeeper with appropriate ACL entries. It will also create a Kubernetes Secret that contains the Base64-encoded SCRAM password for the scram-sha-512 authentication type, or the Base64-encoded certificates and keys for the tls authentication type.

You can retrieve the credentials later in the OpenShift Container Platform by using the name of the KafkaUser. For example, to retrieve the credentials by using the OpenShift Container Platform CLI:

1. Log in to your Red Hat OpenShift Container Platform as a cluster administrator by using the oc CLI (oc login).
2. Use the following command retrieve the required KafkaUser data, adding the KafkaUser name and your chosen namespace:
   
   oc get kafkauser <name> --namespace <namespace> -o jsonpath='{"username: "}{.status.username}{"\nsecret-name: "}{.status.secret}{"\n"}'
   
   The command provides the following output:
   • The principal username
   • The name of the Kubernetes Secret, which includes the namespace, containing the SCRAM password or the TLS certificates.
3. Decode the credentials.
   
   For SCRAM, use the secret-name from step 2 to get the password and decode it:
   
   oc get secret <secret-name> --namespace <namespace> -o jsonpath='{.data.password}' | base64 --decode
   
   For TLS, get the credentials, decode them, and write each certificates and keys to files:
   
   oc get secret <secret-name> --namespace <namespace> -o jsonpath='{.data.ca\.crt}' | base64 --decode > ca.crt

oc get secret <secret-name> --namespace <namespace> -o jsonpath='{.data.user\.crt}' | base64 --decode > user.crt

oc get secret <secret-name> --namespace <namespace> -o jsonpath='{.data.user\.key}' | base64 --decode > user.key

oc get secret <secret-name> --namespace <namespace> -o jsonpath='{.data.user\.p12}' | base64 --decode > user.p12

oc get secret <secret-name> --namespace <namespace> -o jsonpath='{.data.user\.password}' | base64 --decode

The cluster truststore certificate is required for all external connections and is available to download from the Cluster connection panel under the Certificates heading. Upon downloading the PKCS12 certificate, the certificate password will also be displayed.

Similarly, these KafkaUser and Secret resources can be inspected by using the OpenShift Container Platform web console.

Warning: Do not use or modify the internal Event Streams KafkaUsers named <cluster>-ibm-es-kafka-user and <cluster>-ibm-es-georep-source-user. These are reserved to be used internally within the Event Streams instance.

Authorization

What resource types can I secure?

Within Event Streams, you can secure access to the following resource types, where the names in parentheses are the resource type names used in Access Control List (ACL) rules:

• Topics (topic): you can control the ability of users and applications to create, delete, read, and write to a topic.
• Consumer groups (group): you can control an application’s ability to join a consumer group.
• Transactional IDs (transactionalId): you can control the ability to use the transaction capability in Kafka.
• Cluster (cluster): you can control operations that affect the whole cluster, including idempotent writes.

Note: Schemas in the Event Streams Schema Registry are a special case and are secured using the resource type of topic combined with a prefix of __schema_. You can control the ability of users and applications to create, delete, read, and update schemas.

What are the available Kafka operations?

Access control in Apache Kafka is defined in terms of operations and resources. Operations are actions performed on a resource, and each operation maps to one or more APIs or requests.

Implicitly-derived operations

Certain operations provide additional implicit operation access to applications.

When granted Read, Write, or Delete, applications implicitly derive the Describe operation. When granted AlterConfigs, applications implicitly derive the DescribeConfigs operation.

For example, to Produce to a topic, the Write operation for the topic resource is required, which will implicitly derive the Describe operation required to get the topic metadata.

Access Control List (ACL) rules

Access to resources is assigned to applications through an Access Control List (ACL), which consists of rules. An ACL rule includes an operation on a resource together with the additional fields listed in the following tables. A KafkaUser custom resource contains the binding of an ACL to a principal, which is an entity that can be authenticated by the Event Streams instance.

An ACL rule adheres to the following schema:

The resource objects used in ACL rules adhere to the following schema:

Using the information about schemas and resource-operations described in the previous tables, the spec.authorization.acls list for a KafkaUser can be created as follows:

# ...
spec:
# ...
  authorization:
    # ...
    acls:
      - host: '*'
        resource:
          type: topic
          name: 'client-'
          patternType: prefix
        operation: Write

In this example, an application using this KafkaUser would be allowed to write to any topic beginning with client- (for example, client-records or client-billing) from any host machine.

Note: The write operation also implicitly derives the required describe operation that Kafka clients require to understand the data model of a topic.

The following is an example ACL rule that provides access to read Schemas:

    - host: '*'
      resource:
        type: topic
        name: '__schema_'
        patternType: prefix
      operation: Read

Revoking access for an application

As each application will be using credentials provided through a KafkaUser instance, deleting the instance will revoke all access for that application. Individual ACL rules can be deleted from a KafkaUser instance to remove the associated control on a resource operation.