Docker – Avoiding endless tail for Dockerfile CMD

dockerdocker-compose

When creating a generic container is there a better way than running an endless ping or tail to keep the container from exiting?

FROM ubuntu

RUN apt-get update && \
    apt-get install -y \
    python-pip

VOLUME /flask

EXPOSE 8080:8080

CMD ["tail", "-f", "/dev/null"]

All other attempts at keeping a process running exit with code 0, after running docker-compose up

Best Answer

This is expected behavior for "docker-compose up". From the docs (here)

The docker-compose up command aggregates the output of each container. When the command exits, all containers are stopped. Running docker-compose up -d starts the containers in the background and leaves them running.

Related Solutions

Docker – How to override CMD when running a docker image

You could just enter via docker run -it --entrypoint=/bin/bash $IMAGE -i (you 'll launch a new container from the image and get a bash shell in interactive mode), then run the entrypoint command in that container.

You can then inspect the running container in the state it should be running.

EDIT: Since Docker 1.3 you can use exec to run a process in a running container. Start your container as you 'd normally do, and then enter it by issuing:

docker exec -it $CONTAINER_ID /bin/bash

Assuming bash is installed you will be given shell access to the running container.

Docker – How to access an Instance Store Volume in an ECS Task

I finally found the solution. This script pointed me in the right direction.

You need to restart the Docker service.

Apparently, Docker starts before the user data scripts are executed, and it can only access volumes that were mounted when the service started.

So I added this to the end of my userdata script, and that fixed it:

sudo service docker restart

Best Answer

Related Solutions

Docker – How to override CMD when running a docker image

Docker – How to access an Instance Store Volume in an ECS Task

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