[bitnami/kafka] Docker environment variable for topic creation

[cardosomartins]

Name and Version

[bitnami/kafka] - docker env variable for topic creation

What is the problem this feature will solve?

Name and Version
bitnami/kafka

I am dealing with a project in which I need my containers to run only after the Kafka container is up and has a topic running in it.
I cannot create a topic using RUN, CMD or ENTRYPOINT commands in Docker.

What is the feature you are proposing to solve the problem?

The feature would be a docker variable to start a topic automatically and the posisbility of checking whether it's running with a health check.

What alternatives have you considered?

Currently I have another container init_kafka in which I ping to the original kafka container and then I create a topic in it.
Then, my topic dependent containers have a depends_only condition that depend on the init_kafka

### Examples in other docker images
A good example of such a feature that was implemented elsewhere is in wurstmeister image. They have a variable called "KAFKA_CREATE_TOPICS". Something along those lines would work just fine.

[javsalgar]

Hi!

The kafka container has an option to run custom init scripts mounted at /docker-entrypoint-initdb.d

kafka_custom_init_scripts() {
    if [[ -n $(find "${KAFKA_INITSCRIPTS_DIR}/" -type f -regex ".*\.\(sh\)") ]] && [[ ! -f "${KAFKA_VOLUME_DIR}/.user_scripts_initialized" ]]; then
        info "Loading user's custom files from $KAFKA_INITSCRIPTS_DIR"
        for f in /docker-entrypoint-initdb.d/*; do
            debug "Executing $f"
            case "$f" in
            *.sh)
                if [[ -x "$f" ]]; then
                    if ! "$f"; then
                        error "Failed executing $f"
                        return 1
                    fi
                else
                    warn "Sourcing $f as it is not executable by the current user, any error may cause initialization to fail"
                    . "$f"
                fi
                ;;
            *)
                warn "Skipping $f, supported formats are: .sh"
                ;;
            esac
        done
        touch "$KAFKA_VOLUME_DIR"/.user_scripts_initialized
    fi
}

You could try mounting a script that creates a topic. Would that work for your use case?