Wait for a docker container to be ready with command in docker-compose.yml

Question

I have a mysql-db and prisma image in my docker-compose.yml. I want prisma to wait for the db to be ready, cause otherwise prisma keeps restarting and it wont work at all. And I know from here , that I can use ./wait-for-it but I was not able to connect the pieces after searching for a while.

version: '3'
services:
  prisma:
    image: prismagraphql/prisma:1.25
    restart: unless-stopped
    ports:
    - "4001:4466"
    depends_on:
    - db

    # I added this command
    command: ["./wait-for-it.sh", "db:33061", "--"] 

    environment:
      PRISMA_CONFIG: |
        managementApiSecret: server.secret.123
        port: 4466
        databases:
          default:
            connector: mysql
            active: true
            host: db
            port: 3306
            user: ***
            password: ***
  db:
    image: mysql:5.7
    restart: unless-stopped
    command: --default-authentication-plugin=mysql_native_password
    environment:
      MYSQL_USER: ***
      MYSQL_ROOT_PASSWORD: ***
    ports:
      - "33061:3306"
    volumes:
      - /docker/mysql:/var/lib/mysql

I added the command above but nothing changed, not even an error in the logs but as I understand, the command is run inside the container.

1. How do I get the ./wait-for-it.sh into the container?
2. And can this even work this way with the command or does this depend on the prisma-image?
3. Otherwise, how would I achieve the waiting?

I just have the docker-compose file and want to do docker-compose up -d

Answer 1

Now I found out how to include wait-for-it.sh into the container.

I downloaded the wait-for-it.sh into the project folder and then I created a file called Dockerfile with the contents:

FROM prismagraphql/prisma:1.25
COPY ./wait-for-it.sh /app/wait-for-it.sh
RUN chmod +x /app/wait-for-it.sh
ENTRYPOINT ["/bin/sh","-c","/app/wait-for-it.sh db:3306 -t 30 -- /app/start.sh"]

In my docker-compose.yml I replaced image: prismagraphql/prisma:1.25 with build: . which causes a new build from the Dockerfile in my project path.

Now the new image will be built from the prisma image and the wait-for-it.sh will be copied into the new image. Then the ENTRYPOINT is overridden and prisma will wait until the db is ready.

Answer 2

You are confusing internal and external ports. Database is visible on port 3306 inside your network, so you have to wait on db:3306 and not on 33061 .

Port exposing has no effect inside user-defined bridge network, created by default by docker-compose . All ports are visible to containers inside network by default. When you expose port, you make it visible outside network.

Also, make sure what is ENTRYPOINT for image prismagraphql/prisma:1.25 . If it is not /bin/sh -c or other type of shell, your command wont get executed.

UPD

If you get ENTRYPOINT in base image different from /bin/sh -c , you can override it. Supposing you have /bin/sh -c /app/start.sh , you could do following magic:

docker-compose.yml

...
services:
  prisma:
    entrypoint: ["/bin/sh", "-c", "'./wait-for-it.sh db:3306 && /app/start.sh'"]