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Deploying Debezium on Kubernetes

Debezium can be easily deployed on Kubernetes, an open-source container management platform. The deployment leverages the Strimzi project, which aims to simplify the deployment of Apache Kafka on Kubernetes by means of custom resources.

For testing your deployment, you can use minikube, which starts a Kubernetes cluster on your local machine. See the minikube documentation for details on how to install minikube on your machine. If you want to test a Debezium deployment as described in this doc completely on minikube, you need to set up an unsecure container image registry on minikube. To do so, you need start minikube with the --insecure-registry flag:

$ minikube start --insecure-registry "10.0.0.0/24"

10.0.0.1 is the default service cluster IP, so this setup allows pulling images inside the whole cluster. See minikube documentation for more details. You also need to enable registry minikube addon:

$ minikube addons enable registry

Prerequisites

To keep containers separated from other workloads on the cluster, create a dedicated namespace for Debezium. In the remainder of this document, the debezium-example namespace will be used:

$ kubectl create ns debezium-example

Deploying Strimzi Operator

As mentioned above, for the Debezium deployment we will use Strimzi, which manages the Kafka deployment on Kubernetes. Please see the Strimzi deployment documentation for more details on how to deploy Strimzi on your Kubernetes cluster.

The simplest way for installing Strimzi is through the Operator Lifecycle Manager (OLM). If you don’t have OLM installed on your cluster yet, you can install it by running the following command:

$ curl -sL https://github.com/operator-framework/operator-lifecycle-manager/releases/download/v0.20.0/install.sh | bash -s v0.20.0

Now, install Strimzi operator itself:

$ kubectl create -f https://operatorhub.io/install/strimzi-kafka-operator.yaml

Creating Secrets for the Database

Later on, when deploying Debezium Kafka connector, we will need to provide the username and password for the connector to be able to connect to the database. For security reasons, it’s a good practice not to provide the credentials directly, but keep them in a separate secured place. Kubernetes provides the Secret object for this purpose. Besides creating the Secret object itself, we have to also create a role and a role binding so that Kafka can access the credentials.

Let’s create Secret object first:

$ cat << EOF | kubectl create -n debezium-example -f -
apiVersion: v1
kind: Secret
metadata:
  name: debezium-secret
  namespace: debezium-example
type: Opaque
data:
  username: ZGViZXppdW0=
  password: ZGJ6
EOF

The username and password contain base64-encoded credentials (debezium/dbz) for connecting to the MySQL database, which we will deploy later.

Now, we can create a role, which refers the secret created in the previous step:

$ cat << EOF | kubectl create -n debezium-example -f -
apiVersion: rbac.authorization.k8s.io/v1
kind: Role
metadata:
  name: connector-configuration-role
  namespace: debezium-example
rules:
- apiGroups: [""]
  resources: ["secrets"]
  resourceNames: ["debezium-secret"]
  verbs: ["get"]
EOF

We also have to bind this role to the Kafka Connect cluster service account so that Kafka Connect can access the secret:

$ cat << EOF | kubectl create -n debezium-example -f -
apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
  name: connector-configuration-role-binding
  namespace: debezium-example
subjects:
- kind: ServiceAccount
  name: debezium-connect-cluster-connect
  namespace: debezium-example
roleRef:
  kind: Role
  name: connector-configuration-role
  apiGroup: rbac.authorization.k8s.io
EOF

The service account will be created by Strimzi once we deploy Kafka Connect. The name of the service account take the form $KafkaConnectName-connect. Later on, we will the create Kafka Connect cluster named debezium-connect-cluster and therefore we used debezium-connect-cluster-connect here as a subjects.name.

Deploying Apache Kafka

Next, deploy a (single-node) Kafka cluster:

$ cat << EOF | kubectl create -n debezium-example -f -
apiVersion: kafka.strimzi.io/v1beta2
kind: Kafka
metadata:
  name: debezium-cluster
spec:
  kafka:
    replicas: 1
    listeners:
      - name: plain
        port: 9092
        type: internal
        tls: false
      - name: tls
        port: 9093
        type: internal
        tls: true
        authentication:
          type: tls
      - name: external
        port: 9094
        type: nodeport
        tls: false
    storage:
      type: jbod
      volumes:
      - id: 0
        type: persistent-claim
        size: 100Gi
        deleteClaim: false
    config:
      offsets.topic.replication.factor: 1
      transaction.state.log.replication.factor: 1
      transaction.state.log.min.isr: 1
      default.replication.factor: 1
      min.insync.replicas: 1
  zookeeper:
    replicas: 1
    storage:
      type: persistent-claim
      size: 100Gi
      deleteClaim: false
  entityOperator:
    topicOperator: {}
    userOperator: {}
EOF

  • Wait until it’s ready:

$ kubectl wait kafka/debezium-cluster --for=condition=Ready --timeout=300s -n debezium-example

Deploying a Data Source

As a data source, MySQL will be used in the following. Besides running a pod with MySQL, an appropriate service which will point to the pod with DB itself is needed. It can be created e.g. as follows:

$ cat << EOF | kubectl create -n debezium-example -f -
apiVersion: v1
kind: Service
metadata:
  name: mysql
spec:
  ports:
  - port: 3306
  selector:
    app: mysql
  clusterIP: None
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: mysql
spec:
  selector:
    matchLabels:
      app: mysql
  strategy:
    type: Recreate
  template:
    metadata:
      labels:
        app: mysql
    spec:
      containers:
      - image: quay.io/debezium/example-mysql:2.0
        name: mysql
        env:
        - name: MYSQL_ROOT_PASSWORD
          value: debezium
        - name: MYSQL_USER
          value: mysqluser
        - name: MYSQL_PASSWORD
          value: mysqlpw
        ports:
        - containerPort: 3306
          name: mysql
EOF

Deploying a Debezium Connector

To deploy a Debezium connector, you need to deploy a Kafka Connect cluster with the required connector plug-in(s), before instantiating the actual connector itself. As the first step, a container image for Kafka Connect with the plug-in has to be created. If you already have a container image built and available in the registry, you can skip this step. In this document, the MySQL connector will be used as an example.

Creating Kafka Connect Cluster

Again, we will use Strimzi for creating the Kafka Connect cluster. Strimzi also can be used for building and pushing the required container image for us. In fact, both tasks can be merged together and instructions for building the container image can be provided directly within the KafkaConnect object specification:

$ cat << EOF | kubectl create -n debezium-example -f -
apiVersion: kafka.strimzi.io/v1beta2
kind: KafkaConnect
metadata:
  name: debezium-connect-cluster
  annotations:
    strimzi.io/use-connector-resources: "true"
spec:
  version: 3.1.0
  replicas: 1
  bootstrapServers: debezium-cluster-kafka-bootstrap:9092
  config:
    config.providers: secrets
    config.providers.secrets.class: io.strimzi.kafka.KubernetesSecretConfigProvider
    group.id: connect-cluster
    offset.storage.topic: connect-cluster-offsets
    config.storage.topic: connect-cluster-configs
    status.storage.topic: connect-cluster-status
    # -1 means it will use the default replication factor configured in the broker
    config.storage.replication.factor: -1
    offset.storage.replication.factor: -1
    status.storage.replication.factor: -1
  build:
    output:
      type: docker
      image: 10.110.154.103/debezium-connect-mysql:latest
    plugins:
      - name: debezium-mysql-connector
        artifacts:
          - type: tgz
            url: https://repo1.maven.org/maven2/io/debezium/debezium-connector-mysql/{debezium-version}/debezium-connector-mysql-{debezium-version}-plugin.tar.gz
EOF

You have to replace IP address of the registry 10.110.154.103 with the registry where you can push images. In case you run it on minikube with the registry addon, you can push the image into the internal minikube registry. The IP address of the registry can by obtained e.g. by running

$ kubectl -n kube-system get svc registry -o jsonpath='{.spec.clusterIP}'

For simplicity, we’ve skipped the checksum validation for the downloaded artifact. If you want to be sure the artifact was correctly downloaded, specify its checksum via the sha512sum attribute. See the Strimzi documentation for more details.

If you already have a suitable container image either in the local or a remote registry (such as quay.io or DockerHub), you can use this simplified version:

$ cat << EOF | kubectl create -n debezium-example -f -
apiVersion: kafka.strimzi.io/v1beta2
kind: KafkaConnect
metadata:
  name: debezium-connect-cluster
  annotations:
    strimzi.io/use-connector-resources: "true"
spec:
  version: 3.1.0
  image: 10.110.154.103/debezium-connect-mysql:latest
  replicas: 1
  bootstrapServers: debezium-cluster-kafka-bootstrap:9092
  config:
    config.providers: secrets
    config.providers.secrets.class: io.strimzi.kafka.KubernetesSecretConfigProvider
    group.id: connect-cluster
    offset.storage.topic: connect-cluster-offsets
    config.storage.topic: connect-cluster-configs
    status.storage.topic: connect-cluster-status
    # -1 means it will use the default replication factor configured in the broker
    config.storage.replication.factor: -1
    offset.storage.replication.factor: -1
    status.storage.replication.factor: -1
EOF

Also note that we have configured the Strimzi secret provider. This secret provider will create a service account for this Kafka Connect cluster (which we have already bound to the appropriate role), and allow Kafka Connect to access our Secret object.

Creating a Debezium Connector

To create a Debezium connector, you just need to create a KafkaConnector with the appropriate configuration, MySQL in this case:

$ cat << EOF | kubectl create -n debezium-example -f -
apiVersion: kafka.strimzi.io/v1beta2
kind: KafkaConnector
metadata:
  name: debezium-connector-mysql
  labels:
    strimzi.io/cluster: debezium-connect-cluster
spec:
  class: io.debezium.connector.mysql.MySqlConnector
  tasksMax: 1
  config:
    tasks.max: 1
    database.hostname: mysql
    database.port: 3306
    database.user: ${secrets:debezium-example/debezium-secret:username}
    database.password: ${secrets:debezium-example/debezium-secret:password}
    database.server.id: 184054
    topic.prefix: mysql
    database.include.list: inventory
    schema.history.internal.kafka.bootstrap.servers: debezium-cluster-kafka-bootstrap:9092
    schema.history.internal.kafka.topic: schema-changes.inventory
EOF

As you can note, we didn’t use plain text user name and password in the connector configuration, but refer to Secret object we created previously.

Verifying the Deployment

To verify the everything works fine, you can e.g. start watching mysql.inventory.customers Kafka topic:

$ kubectl run -n debezium-example -it --rm --image=quay.io/debezium/tooling:1.2  --restart=Never watcher -- kcat -b debezium-cluster-kafka-bootstrap:9092 -C -o beginning -t mysql.inventory.customers

Connect to the MySQL database:

$ kubectl run -n debezium-example -it --rm --image=mysql:8.0 --restart=Never --env MYSQL_ROOT_PASSWORD=debezium mysqlterm -- mysql -hmysql -P3306 -uroot -pdebezium

Do some changes in the customers table:

sql> update customers set first_name="Sally Marie" where id=1001;

You now should be able to observe the change events on the Kafka topic:

{
...
  "payload": {
    "before": {
      "id": 1001,
      "first_name": "Sally",
      "last_name": "Thomas",
      "email": "sally.thomas@acme.com"
    },
    "after": {
      "id": 1001,
      "first_name": "Sally Marie",
      "last_name": "Thomas",
      "email": "sally.thomas@acme.com"
    },
    "source": {
      "version": "{debezium-version}",
      "connector": "mysql",
      "name": "mysql",
      "ts_ms": 1646300467000,
      "snapshot": "false",
      "db": "inventory",
      "sequence": null,
      "table": "customers",
      "server_id": 223344,
      "gtid": null,
      "file": "mysql-bin.000003",
      "pos": 401,
      "row": 0,
      "thread": null,
      "query": null
    },
    "op": "u",
    "ts_ms": 1646300467746,
    "transaction": null
  }
}