Docker Container(Dockerfile from other image) immediately exit - It is all about Dockerfile not command

Question

I am trying to run Redmin via docker .

Here is what I am going to do

1. Copy redmine:latest docker image to custom image
2. Do some extra setting and make a container
3. Run the custom docker container

So I made Dockerfile like

FROM redmine
CMD ["echo", "Redmine is ready!"]

Then I built image with docker build -t test . .(In the Dockerfile folder)

After that, docker run -d --name=test -p 8080:3000 test .

I expected can find test docker container is run state, but it is exit(0) .

How can I make this container keep alive?

FYI, docker run -d --name=test -p 8080:3000 redmine works fine.

Answer 1

Within your docker image CMD can be used only once. If you have more than one, only the last one will run.

You will need to add the

CMD ["rails", "server", "-b", "0.0.0.0"]

As the cmd for your custom image to run the server. At the moment your CMD only executes echo as soon as that command is executed your container will exit.