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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?
776
It turns out that you cannot include files outside Docker's build context. However, you can copy files from the Dockerfile's parent directory.
The docker build command builds Docker images from a Dockerfile and a “context”. A build's context is the set of files located in the specified PATH or URL . The build process can refer to any of the files in the context. For example, your build can use a COPY instruction to reference a file in the context.
context defines either a path to a directory containing a Dockerfile, or a url to a git repository. When the value supplied is a relative path, it MUST be interpreted as relative to the location of the Compose file.
Let's say we have two Dockerfiles, one for building the backend and another for building the frontend. We can name them appropriately and invoke the build command two times, each time passing the name of one of the Dockerfiles: $ docker build -f Dockerfile.
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 . If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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