Detailed explanation of how to stop the Docker container from automatically exiting

This article briefly introduces the relationship between Docker containers and front-end processes, as well as how to write Dockerfile/docker-compose.yml to elegantly allow containers to run permanently.

The life cycle of a docker container is related to the previous process in the container. This is why we may encounter some containers that end automatically after running for only a few seconds: because there is no resident previous process in the container, the container automatically exits after the previous process ends.

For example, docker hello-world

# Output a bunch of things in a flash docker run --name hello-world hello-world
# You can see that the hello-world container has exited docker ps -a

So how can we prevent the container from exiting automatically? If we want to log in to a pure container such as alpine/centos/ubuntu, install some service components on its basis, and then commit it into our own image.

There are many methods on the Internet that execute a while(true) infinite loop (of course, sleep) when creating a container or use tail -f /dev/null, etc. Anyway, the purpose is to start a permanent front-end process. In fact, we can use the interactive and tty parameters of the docker container more elegantly to start the sh/bash (*nix system must have) command as a pre-command, so that the container will not exit automatically.

For example, use the alpine image as the base image and create a small alpine system container so that it can run permanently, so that we can log in and interactively execute certain commands.

# Create a container using the alpine system image # -i interactive=true to open stdin
# -t tty=true assigns the session terminal# -d daemon mode can be omitted and you can directly enter the container. You need to press ctrl+p+q to exit# You cannot exit. exit is equivalent to ending the sh session and the container will exitdocker run -it -d --name alpine alpine sh
# alpine must be running docker ps
# Log in to the container docker exec -it alpine sh
# apline uses apk as package management# Install a small train# You can use docker commit -m "alpine with sl cmd" -a "big_cat" alpine big_cat/alpine_sl to generate a new image apk add sl
# Exit the container Note: Only -d can be used. If you do not use -d to start the sh terminal directly, you cannot exit. Otherwise, the container will also exit.

Submit container changes to generate a new image

docker commit -m "alpine with sl cmd" -a "big_cat" alpine big_cat/alpine_sl
docker images
# If you have an account, publish it to docker hub: docker push big_cat/alpine_sl

# You don't need to specify the -it parameter when you stop/start the container later docker stop alpine
docker start alpine

Submit container changes to generate a new image

docker commit -m "alpine with sl cmd" -a "big_cat" alpine big_cat/alpine_sl
docker images
# If you have an account, publish it to docker hub: docker push big_cat/alpine_sl

The above command actually uses the sh/bash session terminal as the front process so that the container will not exit automatically.

If you think it's crude to write like this when creating a container, it doesn't matter, we can push all of this to docker-compose
docker-compose.yml

version: '3'

services:
  big_cat_alpine:
    container_name: big_cat_alpine
    image: alpine
    stdin_open: true # -i interactive
    tty: true # -t tty
    privileged: true
    entrypoint: ["sh"] # execute sh

Create container & log in to container

docker-compose up -d big_cat_alpine ./
docker ps
docker exec -it big_cat_alpine sh

Pass the two parameters into docker-compose and start the service container after orchestration.

The above is the full content of this article. I hope it will be helpful for everyone’s study. I also hope that everyone will support 123WORDPRESS.COM.