[id="deploying-debezium-on-kubernates"]
= Deploying {prodname} on Kubernetes

:linkattrs:
:icons: font
:toc:
:toclevels: 3
:toc-placement: macro

toc::[]

{prodname} can be easily deployed on https://kubernetes.io/[Kubernetes], an open-source container management platform.
The deployment leverages the https://strimzi.io/[Strimzi] project, which aims to simplify the deployment of Apache Kafka on Kubernetes by means of _custom resources_.

[NOTE]
====
For testing your deployment, you can use https://minikube.sigs.k8s.io/docs/[minikube], which starts a Kubernetes cluster on your local machine.
See the https://minikube.sigs.k8s.io/docs/start/[minikube documentation] for details on how to install minikube on your machine.
If you want to test a {prodname} 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:

[source,subs="attributes",options="nowrap"]
----
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 https://minikube.sigs.k8s.io/docs/handbook/registry/#enabling-insecure-registries[minikube documentation] for more details.
You also need to enable `registry` minikube addon:

[source,subs="attributes",options="nowrap"]
----
minikube addons enable registry
----

====

== Prerequisites

To keep containers seprated from rest fo the cluster, create dedicated namespace for {prodname}.
In the rest of this doc, `debezium-example` will be used:

[source,subs="attributes",options="nowrap"]
----
kubectl create ns debezium-example
----

As mentioned above, for the {prodname} deployment we will use Strimzi, which manages Kafka deployment on Kubernates.
Please see https://strimzi.io/docs/operators/latest/deploying.html[Strimzi deployment documentation], for more details how to deploy Strimzi on your Kubernates cluster.

For testing purposes, you can use following, simplified and unsecured,  approach.

* First, https://strimzi.io/downloads/[download] recent Strimzi release and unpack it in your local directory.

* Create dedicated namespace for Strimzi Kafka Cluster Operator:

[source,subs="attributes",options="nowrap"]
----
kubectl create ns kafka
----

* Modify the downloaded source files to use `kafka` namespace for installation of Strimzi Kafka Cluster Operator:

[source,subs="attributes",options="nowrap"]
----
sed -i 's/namespace: .*/namespace: kafka/' install/cluster-operator/*RoleBinding*.yaml
----

and set `STRIMZI_NAMESPACE` to `debezium-example` namespace in `install/cluster-operator/060-Deployment-strimzi-cluster-operator.yaml`:

[source,subs="attributes",options="nowrap"]
----
env:
  - name: STRIMZI_NAMESPACE
    value: debezium-example
----

* Deploy Kafka cluster:

[source,bash]
----
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
----

* And wait until it's ready:

[source,subs="attributes",options="nowrap"]
----
kubectl wait kafka/debezium-cluster --for=condition=Ready --timeout=300s -n debezium-example
----

In this doc, MySql will be used as an example.
Besides running a pod with MySql, appropriate service which will point to the pod with DB itself is needed.
It can be created e.g. as follows:

[source,bash]
----
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:1.9
        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 {prodname} Connector

To deploy {prodname} connector, one needs to deploy Kafka Connect cluster with proper plugin and create the connector itself.
As the first step, Kafka Connect Docker image with the plugin has to be created.
If you have already Docker image built and available in registry, you can skip this step.
In this doc, MySql connector will be used as an example.

=== Creating Kafka Connect Cluster

Again, we will use Strimzi for creating Kafka Connect cluster.
Strimzi is able to help with building Docker image as well and can built and push required Docker image for us.
In fact both tasks can be merged together and instructions for building Docker image can be provided directly in connector object specification:

[source,bash]
----
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:
    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/1.8.1.Final/debezium-connector-mysql-1.8.1.Final-plugin.tar.gz
            sha512sum: dff3e1f973ab203490d19337fac65e7545fbd70e3f22555e6ca74b3c734160140cbef5905b9f138f8b56616e0af5a41a8b2b7f09497d9cc62f64863017bdc088
EOF
----

[NOTE]
====
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 registry addon, you can push the image into internal minikube registry.
The IP address of the registry can by obtained e.g. by running

[source,subs="attributes",options="nowrap"]
----
kubectl -n kube-system get svc registry -o jsonpath='{.spec.clusterIP}'
----

====

If you already have Docker image in Docker registry, you can used simplified version:

[source,bash]
----
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:
    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
----

=== Creating {prodname} Connector

To create {prodname} connector, you just need to create connector with appropriate configuration, MySql in this case:

[source,bash]
----
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: debezium
    database.password: dbz
    database.server.id: 184054
    database.server.name: mysql
    database.include.list: inventory
    database.history.kafka.bootstrap.servers: debezium-cluster-kafka-bootstrap:9092
    database.history.kafka.topic: schema-changes.inventory
EOF
----

== Verifying the Deployment

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

[source,subs="attributes",options="nowrap"]
----
kubectl run -n debezium-example -it --rm --image=quay.io/debezium/kafka:1.9  --restart=Never watcher -- watch-topic -a -k mysql.inventory.customers
----

connect to MySql database:

[source,subs="attributes",options="nowrap"]
----
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 `customers` table:

[source,subs="attributes",options="nowrap"]
----
update customers set first_name="Sally Marie" where id=1001;
----

and observer the change in Kafka topic watcher:

[source,json]
----
{
...
  "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": "1.8.1.Final",
      "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
  }
}
----