CODEWITHSUNDEEP
dockercontainersrestartcoreos
Sushil Verma
Sushil Verma

Reputation: 697

Auto-restart Docker container when contents of host folder change

I am running a Docker container in CoreOS (host) and mounted a host folder with a container's folder.

docker run -v /home/core/folder_name:/folder_name <container_name>

Now, each time I am changing (insert/delete) some file in that host folder (folder_name), I have to restart the container (container_name) to see the effects.

docker restart <container_name>

Is there any way from the host side or docker side to restart it automatically when there is a change (insert/delete) in the folder?

Upvotes: 2

Views: 10118

Answers (1)

gpwclark
gpwclark

Reputation: 66

Restarting the docker container on a folder change is rather antithetical to the whole notion of the -v command in the first place. If you really really really need to restart the container in the manner you are suggesting then the only way to do it is from the docker host. There are a couple tools (I can name off the top of my head, there are definitely more) you could use to monitor the host folder and when a file is inserted or deleted you could trigger the docker restart <container_name> command. Those tools are incron and inotify-tools. Here is another question someone asked similar to yours and the answer recommended using one of the tools I suggested.

Now, there is no way that the files in the host folder are not being changed in the docker container as well. It must be that the program you are using in the docker container isn't updating it's view of the /folder_name folder after it starts up. Is it possible for you to force the program you are running in the docker container to refresh or update? The -v command works via bind mounting and has been a stable feature in docker for quite a while. With bind mounting, the home/core/folder_name folder IS (for all practical purposes) the same folder as /folder_name in the container.

run the command

docker run -t -i -v /home/core/folder_name:/folder_name <container_name> /bin/sh

This command gives you an interactive shell within the container. In this shell issue the command:

cd /folder_name; touch a_file

Now go to /home/core/folder_name on the docker host in a shell or some file browser. The file a_file will be there. You can delete that file on the host and go back to the shell running in the docker container and run ls /folder_name. The file a_file will not be there.

So, you either need to use inotify or incron to go about restarting your container anytime a file changes on the host, or figure out how to work with the program you are running in the docker container to have it update its view of the /folder_name folder.

Upvotes: 2

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