Docker: Prevent container from exiting immediately after creation

An example of how to prevent a Docker container from exiting with return code 0 immediately after creation.

In case a Docker image is built with the container entry point like: CMD [“bin/sh”], a container created from such image may exit immediately after creation.

If the container is created using docker run -it, like in this example:

docker run -it ygrebnov/node-angularcli:latest ash

you can access it and work with it. As soon as you exit the container, it is stopped.

docker ps -a

You can see the Exited (0) About a minute ago status displayed for your container.

If the container is created using docker-compose with basic configuration, the container status is Exited(0) after:

docker-compose up -d

If there is a restart policy defined for the service in the docker-compose.yml, the container will be constantly restarting. In case of Exited(0) container status, most likely that docker logs <container_id> command will show nothing.

Such behavior is explained by the fact that the created docker container process with PID 1 is started and successfully finished with the return code 0. Docker container is exited as soon as the process with PID 1 finishes. In our case, the process with PID 1 is /bin/sh.

In order to prevent the docker container from exiting immediately after creation, tty should be set to true in the docker-compose.yml file. tty: true in docker-compose corresponds to the docker run -it.

With tty: true for the service, the created by docker-compose up -d container status is Up.

An example of the docker image with CMD ["bin/sh"]: ygrebnov/node-angularcli. Docker Hub: https://hub.docker.com/repository/docker/ygrebnov/node-angularcli

An example of a docker-compose.yml using ygrebnov/node-angularcli image:

version: '3.5'
services:
  mongo:
    image: mongo
    container_name: mean-mongo
    restart: unless-stopped
    environment:
      MONGO_INITDB_ROOT_USERNAME: admin
      MONGO_INITDB_ROOT_PASSWORD: admin
    volumes:
      - mongo-volume:/data/db
    networks:
      - mean-network
    
  node:
    image: ygrebnov/node-angularcli:latest
    container_name: mean-node
    tty: true
    restart: unless-stopped
    ports:
      - "44120:8080"
    volumes:
      - node-volume:/usr/src/app
    networks:
      - mean-network

volumes:
  mongo-volume:
  node-volume:
networks:
  mean-network:
    driver: bridge