I want to setup some configuration when my container starts, for this I am using shell scripts. But my container will exits as soon as my scripts ends, I have tried with -d flag / detached mode but It will never run in detached mode.
Below is my Dockerfile
FROM ubuntu:14.04
ADD shell.sh /usr/local/bin/shell.sh
RUN chmod 777 /usr/local/bin/shell.sh
CMD /usr/local/bin/shell.sh
Below is my shell script
#!/bin/bash
echo Hello-docker
Run without any flag docker run hello-docker This will print 'Hello-docker' on my console and exits Run with -itd flags docker run -itd hello-docker and as below my console output, This time also will exits soon. :( The difference I saw is in COMMAND section when I run other images command section will shows "/bin/bash" and will continue in detached mode. And when I run my image in container with shell script COMMAND section will show "/bin/sh -c /usr/loca", and Exit. I want to run container till I not stop it manually.
EDIT:
After adding ENTRYPOINT instruction in Dockerfile, this will not execute my shell script :(
FROM ubuntu:14.04
ADD shell.sh /usr/local/bin/shell.sh
RUN chmod 777 /usr/local/bin/shell.sh
CMD /usr/local/bin/shell.sh
ENTRYPOINT /bin/bash
As per docker documentation here
CMD will be overridden when running the container with alternative arguments, so If I run docker image with some arguments as below, will not execute CMD instructions. :(
sudo docker run -it --entrypoint=/bin/bash <imagename>
A docker container will run as long as the CMD
from your Dockerfile takes.
In your case your CMD
consists of a shell script containing a single echo. So the container will exit after completing the echo.
You can override CMD
, for example:
sudo docker run -it --entrypoint=/bin/bash <imagename>
This will start an interactive shell in your container instead of executing your CMD
. Your container will exit as soon as you exit that shell.
If you want your container to remain active, you have to ensure that your CMD
keeps running. For instance, by adding the line while true; do sleep 1; done
to your shell.sh file, your container will print your hello message and then do nothing any more until you stop it (using docker stop in another terminal).
You can open a shell in the running container using docker exec -it <containername> bash
. If you then execute command ps ax
, it will show you that your shell.sh is still running inside the container.
Finally with some experiments I got my best result as below
There is nothing wrong with my Dockerfile as below it's correct.
FROM ubuntu:14.04
ADD shell.sh /usr/local/bin/shell.sh
RUN chmod 777 /usr/local/bin/shell.sh
CMD /usr/local/bin/shell.sh
What I do to get expected result is, I just add one more command(/bin/bash) in my shell script file as below and vola everything works in my best way.
#!/bin/bash
echo “Hello-docker” > /usr/hello.txt
/bin/bash
RUN /bin/echo -e "#!/bin/bash\npython welcome.py\n/bin/bash" > /usr/local/bin/onstartup.sh && chmod 777 /usr/local/bin/onstartup.sh
then CMD /usr/local/bin/onstartup.sh
# Create an executable file that starts the server... # A unix executable .sh-file must start with #!/bin/bash. '\n' means 'newline'. RUN printf '#!/bin/bash\n/etc/NX/nxserver --startup\n/bin/bash'"" > /etc/NX/nxserverStart.sh # .. and make it actually executable ... RUN chmod +x /etc/NX/nxserverStart.sh # Start the nomachine-remote server when the container runs, and ... CMD ["/etc/NX/nxserverStart.sh"]
and running the container with docker run -d -t -p 4000:4000 --name 'linux_remote_pc' 'linux_remote_pc_image'
You can also modify your first Dockerfile, replacing
CMD /usr/local/bin/shell.sh
by
CMD /usr/local/bin/shell.sh ; sleep infinity
That way, your script does not terminate, and your container stays running.
docker exec container_id__or_name ls -l
bash -C '/path/to/start.sh';'bash'
that way,when your script completes, you have a shell, see markbetz.net/2014/03/17/…
CMD bash -C '/path/to/start.sh';'bash'
At your start shell append a line code: tail -f /dev/null
or /bin/bash
to make sure you shell done and suspend a process in system so that docker container not shutdown.Don't forget to give "chmod +x" access to start.sh. there is demo:
#!/bin/bash
cp /root/supervisor/${RUN_SERVICE}.ini /etc/supervisor/conf.d/
sleep 1
service supervisor start
/bin/bash
Try
CMD /bin/bash -c 'MY_COMMAND_OR_SHELL_SCRIPT; /bin/bash'
Trying an explanation here to the answer of @lanni654321. sh
shell is standard in Dockerfile. You must call bash
shell to start bash
with .bashrc
, many commands also need RUN /bin/bash -c '...'
in the same way as in CMD
above, since sh
shell is often not enough. If you add 'bash' in the end of CMD
, the container will not exit because the image was committed with something that is still open.
See “/bin/sh: 1: MY_COMMAND: not found” for an error caused by sh
and solved by bash
.
I think that you will usually not need this. You can just use RUN /bin/bash -c '...'
, in my case, this could do anything that can be done in a base image before you go into varying details in docker-compose
to start the containers.
But that is all not needed if you need to just have a container running without exiting. Just
docker run -dit --name MY_CONTAINER MY_IMAGE:latest
and then
docker exec -it MY_CONTAINER /bin/bash
and you should be in the bash of the container, and it should not exit.
Or if the exit happens during docker-compose
, use
command: bash -c "MY_COMMAND --wait"
Success story sharing
CMD
running. I've added an example to my answer.