files

The files module can be used to copy directories from config/files to any location in your image at build time, as long as the location exists at build time (e.g. you can’t put files in /home/<username>, because users haven’t been created yet prior to first boot).

If you want to place files into /etc, there are two ways to do it:

copying a directory in config/files directly to /etc to add all of its files at build time, or
putting the files you want there in /usr/etc as part of copying things over to /usr, which rpm-ostree will then copy to /etc at runtime/boot.

Typically, you will want to use the latter option (putting files in /usr/etc) in almost all cases, since that is the proper directory for “system” configuration templates on atomic Fedora distros, whereas /etc is meant for manual overrides and editing by the machine’s admin after installation (see issue https://github.com/blue-build/legacy-template/issues/28). However, if you really need something to be in /etc at build time --- for instance, if you for some reason need to place a repo file in /etc/yum.repos.d in such a way that it is used by a rpm-ostree module later on --- then the former option will be necessary.

The files module cannot write to directories that will later be symlinked to point to other places (typically /var) by rpm-ostree.

This is because it doesn’t make sense for a directory to be both a symlink and a real directory that has had actual files directly copied to it, so the files module copying files to one of those directories (thereby instantiating it as a real directory) and rpm-ostree’s behavior regarding them will necessarily conflict.

For reference, according to the official Fedora documentation, here is a list of the directories that rpm-ostree symlinks to other locations:

/home → /var/home
/opt → /var/opt
/srv → /var/srv
/root → /var/roothome
/usr/local → /var/usrlocal
/mnt → /var/mnt
/tmp → /sysroot/tmp

So don’t use files to copy any files to any of the directories on the left, because at runtime rpm-ostree will want to link them to the ones on the right, which will cause a conflict as explained above.

Example configuration

modules:
  - type: files
    files:
      - usr: /usr # copies config/files/usr into your images /usr
                  # put configuration files you want in /etc/ on a *booted*
                  # system in /usr/etc/ in the image.
      - etc: /etc # copies config/files/etc into your image's /etc immediately,
                  # for use with further modules.