Debezium Connect Docker Image

A Debezium Docker Image that is entirely configurable via environment variables; It removes the need to manually POST connector configs to Connect's REST API.

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Example

docker run --rm -ti dhet/debezium-connect \
  -e BOOTSTRAP_SERVERS=kafka:29092 \
  -e CONFIG_STORAGE_TOPIC=debezium-config \
  -e OFFSET_STORAGE_TOPIC=debezium-offset \
  -e STATUS_STORAGE_TOPIC=debezium-status \
  -e DEBEZIUM_CONFIG_CONNECTOR_CLASS=io.debezium.connector.postgresql.PostgresConnector \
  -e DEBEZIUM_CONFIG_DATABASE_HOSTNAME=database \
  -e DEBEZIUM_CONFIG_DATABASE_PORT=5432 \
  -e DEBEZIUM_CONFIG_DATABASE_PASSWORD=postgres \
  -e DEBEZIUM_CONFIG_DATABASE_USER=postgres \
  -e DEBEZIUM_CONFIG_DATABASE_SERVER_NAME=postgres \
  -e DEBEZIUM_CONFIG_DATABASE_DBNAME=postgres

See the example folder for a Docker compose example. Running docker-compose up in that directory will spin up

• a single-broker Kafka setup, including Zookeeper
• a PostgreSQL database
• a Debezium connector that monitors the database and publishes changes to Kafka

Configuration

This image adds a thin layer on top of the official Debezium connect image. As such, it supports all environment variables listed in the documentation, such as

• CONFIG_STORAGE_TOPIC
• BOOTSTRAP_SERVERS
• etc.

Configuring Connect

Similarly, all Kafka Connect configuration options are supported. As described in the docs they are prefixed with CONNECT_ and the dots in the property name is translated into an underscore. For example

• CONNECT_SSL_TRUSTSTORE_LOCATION translates into ssl.truststore.location=...
• CONNECT_KEY_CONVERTER translates into key.converter=...
• etc.

Configuring Debezium

In addition to the above, all configuration properties which are typically specified in a Debezium config file can be configured via environment variables. The translation scheme follows the example of Connect, except that the prefix is DEBEZIUM_CONFIG_ (this can be reconfigured via the ENV_PREFIX environment variable)

Example:

• DEBEZIUM_CONFIG_CONNECTOR_CLASS translates into connector.class=...
• DEBEZIUM_CONFIG_DATABASE_HOSTNAME translates into database.hostname=...
• DEBEZIUM_CONFIG_DATABASE_PORT translates into database.port=...
• etc.

⚠️ The image is not capable of identifying invalid properties and is thus susceptible to typos. It simply translates the environment variables in accordance with the aforementioned renaming rules.

Additionally, the connector's name can be specified via CONNECTOR_NAME env var (the default connector name is "debezium")

How it works

Setting up a Kafka connector involves sending an HTTP request to the connector's REST API which is often done as a manual step. The API takes the config and stores it in a log-compacted Kafka topic. Connectors are therefore inherently stateful and their deployment is a pain to automate.

This image tries to alleviate this by making the connector configurable through environment variables. When the container starts it builds a config file from the specified environment variables and PUTs it to the API. This is an idempotent operation=the first request will set up a new connector, and all subsequent requests will overwrite the existing configuration. As a result, starting the container several times with the same configuration will always have the same effect.

⚠️ The image is not capable of deleting existing configurations so a manual cleanup via HTTP DELETE is necessary in case Debezium is not needed anymore.