Question
How can I include files from outside of Docker's build context using the "ADD" command in the Docker file?
From the Docker documentation:
The path must be inside the context of the build; you cannot ADD ../something/something, because the first step of a docker build is to send the context directory (and subdirectories) to the docker daemon.
I do not want to restructure my whole project just to accommodate Docker in this matter. I want to keep all my Docker files in the same sub-directory.
Also, it appears Docker does not yet (and may not ever) support symlinks: Dockerfile ADD command does not follow symlinks on host #1676.
The only other thing I can think of is to include a pre-build step to copy the files into the Docker build context (and configure my version control to ignore those files). Is there a better workaround for than that?
Answer
The best way to work around this is to specify the Dockerfile independently of the build context, using -f.
For instance, this command will give the ADD command access to anything in your current directory.
docker build -f docker-files/Dockerfile .
Update : Docker now allows having the Dockerfile outside the build context (fixed in 18.03.0-ce). So you can also do something like
docker build -f ../Dockerfile .
