Copy file from Docker container to Host using Dockerfile

Question

I'm using a docker container for compiling a code that I many not necessarily want to dockerize. I have set up an image with the necessary build tools but I would like to get the compiled file somehow out of the container without using the docker cp container:/file host/file command. In other words, I would like automate this process so that after build is completed, the generated files would be copied to the host.

Can the copy command in Dockerfile COPY <source> <target> be used for this purpose? If no, then what is the solution?

What about [Docker volumes](https://docs.docker.com/storage/volumes/)? — Kunal Nagpal, Jun 13 '22 at 07:27
Yes. After the in-container compilation is done, the build result(s) can be placed in the mounted directory, becoming available to the underlying host. This is also how other Docker-based hosting platforms export application logs from the running container, etc. — Kunal Nagpal, Jun 13 '22 at 07:30
@KunalNagpal: No, not using volumes (--mount, -v command). Just something that copies the file from the container to host without forcing the user to add any configuration — Arnold Zahrneinder, Jun 13 '22 at 07:34
why you don't use the docker scale? as ı understood you, you want to copy the container — dılo sürücü, Jun 13 '22 at 07:37
Volumes won't work as they're only available at container run time, and you want to do this at image build time if I understand you correctly. — Hans Kilian, Jun 13 '22 at 07:43
@HansKilian: However, I can also run the container for one time to compile the code, but need to get file out of it. — Arnold Zahrneinder, Jun 13 '22 at 07:45
The linked question suggests `docker create`ing a container that you can `docker cp` out of. You could also build an image with just the tools but not the source code, and `docker run` the compiler with the source and output directories bind-mounted with `-v` options (this is how for instance Jenkins works). — David Maze, Jun 13 '22 at 10:35

score 1 · Accepted Answer · answered Jun 13 '22 at 07:54

You can't copy from a build process to the host context using COPY.

If you need the image and also the executable on the host, then the only way I can think of is a server to push the executable to. That can be something like SSH where you use scp to copy it. Or you could use a web server and use curl to do a POST of the file. Lots of options, but they all require a server you can send the executable to.

Another option is (like you say yourself) to run the image after you've built it and then use docker cp to copy the file from the container to the host.

Copy file from Docker container to Host using Dockerfile

1 Answers1