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I am trying to run a simple docker container with my web application installed (Not using docker file). During the testing I would always run a container using -t -i option and then start the tomcat service inside it by running a shell script. How when I am moving to production I dont want to use the -t -i option any more and just need my Tomcat service to start and be the only primary service.
I trying pointing the entrypoint to the start up script for starting tomcat but the container terminates after that script finishes. How do I run a container, start a service and keep that service as the single primary service of the container?
Note: I read some posts about supervisor but not sure if I would need to start building my image from scratch if I go that route? I would prefer not doing that.
Any suggestions?
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If you usually run a container with the -i flag, you leave STDIN open allowing you access to the containers entrypoint or it could be a bash shell. To achieve what you want, you can run the container in a detached state passing your commands into docker run directly.
The easiest way to keep the container running is to change its entry point to a command that will continue running forever. Let's use tail -f /dev/null . Rechecking the running container via docker ps -a we can see that our container has been up and running for several seconds and hasn't stopped yet.
Detaching Without StoppingPress Ctrl-P, followed by Ctrl-Q, to detach from your connection. You'll be dropped back into your shell but the previously attached process will remain alive, keeping your container running. You can check this by using docker ps to get a list of running containers.
If there's no terminal attached, then your shell process will exit, and so the container will exit. You can stop this by adding --interactive --tty (or just -it ) to your docker run ... command, which will let you type commands into the shell.
If you have a Dockerfile that uses an entrypoint pattern, it will look something like this:
(Dockerfile)
FROM ubuntu
...Some configuration steps...
add start.sh /start.sh
ENTRYPOINT ["/start.sh"]
All you need to do is make sure your start.sh script 'hangs' in some way. Some people like to tail the syslogs, but tailing any file that exists will work.
(start.sh)
#!/bin/bash
service Your_Service_Or_Whatever start
tail -f /var/log/dmesg
A shorter version:
FROM ubuntu
...Some configuration steps...
ENTRYPOINT ["/bin/sh", "-c", "while true; do sleep 1; done"]
tested with Docker version 1.12.1, build 23cf638
Use docker --version to find out your version
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