Docker follow symlink outside context

Question

Yet another Docker symlink question. I have a bunch of files that I want to copy over to all my Docker builds. My dir structure is:

parent_dir
    - common_f         


        

Answer 1

I know that it breaks portability of docker build, but you can use hard links instead of symbolic:

ln /some/file ./hardlink

Answer 2

instead of using simlinks it is possible to solve problem administratively by just moving files from sites_available to sites_enabled instead of copying or making simlinks

so your site config will be in one copy only in site_available folder if it stopped or something or in sites_enabled if it should be used

Answer 3

If anyone still has this issue I found a very nice solution on superuser.com:

https://superuser.com/questions/842642/how-to-make-a-symlinked-folder-appear-as-a-normal-folder

It basically suggests using tar to dereference the symlinks and feed the result into docker build:

$ tar -czh . | docker build -

Answer 4

That is not possible and will not be implemented. Please have a look at the discussion on github issue #1676:

We do not allow this because it's not repeatable. A symlink on your machine is the not the same as my machine and the same Dockerfile would produce two different results. Also having symlinks to /etc/paasswd would cause issues because it would link the host files and not your local files.

Answer 5

One possibility is to run the build in the parent directory, with:

$ docker build [tags...] -f dir1/Dockerfile .

(Or equivalently, in child directory,)

$ docker build  [tags...] -f Dockerfile ..

The Dockerfile will have to be configured to do copy/add with appropriate paths. Depending on your setup, you might want a .dockerignore in the parent to leave out things you don't want to be put into the context.