How do I create a Cassandra keyspace automatically with docker-compose?

Question

I have a golang service that run in a container, along with a cassandra db. This is running like this :

services:
  cassandra:
    image: cassandra:4.0
      ...    
      healthcheck:
      test: ["CMD-SHELL", "[ $$(nodetool statusgossip) = running ]"]
      interval: 30s
      timeout: 10s
      retries: 5

  my_service:
    ...
    command: ./my_service
    depends_on:
      cassandra:
        condition: service_healthy
    environment:
      ...

with a dockerfile like this

# syntax = docker/dockerfile:experimental

FROM ...

COPY ./bin/reply-by-email .
ENTRYPOINT ["./my_service"]

In the code I connect to the DB while specifying the keyspace that I created manually. But I need to have the keyspace created automatically when I perform the docker-compose up

Do you have any idea how to perform this ?

Answer 1

I did it this way:

1. Bash script init.sh:

#!/usr/bin/env bash

until printf "" 2>>/dev/null >>/dev/tcp/cassandra/9042; do 
    sleep 5;
    echo "Waiting for cassandra...";
done

echo "Creating keyspace and table..."
cqlsh cassandra -u cassandra -p cassandra -e "CREATE KEYSPACE IF NOT EXISTS test WITH replication = {'class': 'SimpleStrategy', 'replication_factor': '1'};"
cqlsh cassandra -u cassandra -p cassandra -e "CREATE TABLE IF NOT EXISTS test.test (sensor_id uuid, registered_at timestamp, temperature int, PRIMARY KEY ((sensor_id), registered_at));"

2. An init container in the docker-compose.yaml

  init:
    image: cassandra:4
    depends_on:
      - cassandra
    restart: "no"
    entrypoint: ["/init.sh"]
    volumes:
      - ./init.sh:/init.sh

It works as a charm, full implementation is here if you need real code.