The local configuration of the project I'm working on involves changing several files in complicated ways that cannot be committed to any submitted branches. To work around this I've committed these local configuration changes to a dedicated local branch config, and have been running this bash script config.sh after starting a new work branch:
#!/bin/bash
# put relevant config files in array
mapfile -t files < <(git diff config develop --name-only)
# overwrite only those files to my working directory
git checkout config -- ${files[@]}
# unstage them so they aren't accidentally committed
git reset HEAD ${files[@]}
echo The following files were successfully overwritten for local configuration:
printf '\t%s\n' "${files[@]}"
Along with another .deconfig script that does the same in reverse. Run directly from the terminal, these scripts have been working fine, but I'd like to streamline the process further using git's clean and smudge filters. So I created a .gitattributes file:
*.* filter=config
and then added this to my .git/config file:
[filter "config"]
smudge = ./config.sh
clean = ./deconfig.sh
However, it just isn't working. If I had to guess it's because git isn't expecting me to run an additional checkout as part of a filter, which itself runs after the checkout command against all files. Most use cases for smudge and clean seem to involve simple find and replace operations, but that approach would be complicated to implement and difficult to maintain given the complexity of changes needed. I could store the configuration files in a static, external directory somewhere, but I'd like to smudge and clean based off the same configuration branch because the local configuration itself frequently evolves and benefits from versioning alongside the rest of the project, and ideally the branch could be used as a baseline for other devs for their local configuration. Git's filter-branch might be a better fit but git's own documentation recommends against using it at all. Is there a way to do this? Is there something wrong with my git configuration? Could the script itself be causing a problem? Any other possible approaches?
Although it is not documented anywhere, you cannot change the state of the working tree with a smudge or clean filter. Git expects to invoke the filter once for each file by piping data into it and reading the data from the standard output. In other words, these filters are intended to be invoked on a per-file basis and process only that file, not by modifying the working tree state.
The best solution to your problem is to avoid keeping a separate branch. Simply keep all of the files, both development and production, in some directory, and use a script to copy the correct one into place. The location of the running config file should be ignored, so the script won't cause Git to show anything as modified. Alternatively, keep a template somewhere, and have the script generate the appropriate one based on the environment. This is good if you have secrets for production that should not be checked in; you can pass them to the script through the environment and have the right values generated.
What you're doing is related to ignoring tracked files, which, as outlined in the Git FAQ, generally can't be done successfully.