Run a service automatically in a docker container

Question

I'm setting up a simple image: one that holds Riak (a NoSQL database). The image starts the Riak service with riak start as a CMD. Now, if I run it as a daemon with docker run -d quintenk/riak-dev, it does start the Riak process (I can see that in the logs). However, it closes automatically after a few seconds. If I run it using docker run -i -t quintenk/riak-dev /bin/bash the riak process is not started (UPDATE: see answers for an explanation for this). In fact, no services are running at all. I can start it manually using the terminal, but I would like Riak to start automatically. I figure this behavior would occur for other services as well, Riak is just an example.

So, running/restarting the container should automatically start Riak. What is the correct approach of setting this up?

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For reference, here is the Dockerfile with which the image can be created (UPDATE: altered using the chosen answer):

FROM ubuntu:12.04 RUN apt-get update RUN apt-get install -y openssh-server curl  RUN curl http://apt.basho.com/gpg/basho.apt.key | apt-key add - RUN bash -c "echo deb http://apt.basho.com precise main > /etc/apt/sources.list.d/basho.list" RUN apt-get update RUN apt-get -y install riak RUN perl -p -i -e 's/(?<=\{http,\s\[\s\{")127\.0\.0\.1/0.0.0.0/g' /etc/riak/app.config EXPOSE 8098  CMD /bin/riak start && tail -F /var/log/riak/erlang.log.1 

EDIT: -f changed to -F in CMD in accordance to sesm his remark

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MY OWN ANSWER

After working with Docker for some time I picked up the habit of using supervisord to tun my processes. If you would like example code for that, check out https://github.com/Krijger/docker-cookbooks. I use my supervisor image as a base for all my other images. I blogged on using supervisor here.

Answer 1

To keep docker containers running, you need to keep a process active in the foreground.

So you could probably replace that last line in your Dockerfile with

CMD /bin/riak console 

Or even

CMD /bin/riak start && tail -F /var/log/riak/erlang.log.1 

Note that you can't have multiple lines of CMD statements, only the last one gets run.

Answer 2

Using tail to keep container alive is a hack. Also, note, that with -f option container will terminate when log rotation happens (this can be avoided by using -F instead).

A better solution is to use supervisor. Take a look at this tutorial about running Riak in a Docker container.