HowTo have specific .gitignore for each git branch

gitignore_per_git_branch.md

How to have specific .gitignore for each git branch

Objective

My objective is to have some production files ignored on specific branches. Git doesn't allow to do it.

Solution

My solution is to make a general .gitignore file and add .gitignore.branch_name files for the branches I want to add specific file exclusion. I'll use post-checkout hook to copy those .gitignore.branch_name in place of .git/info/exclude each time I go to the branch with git checkout branch_name.

Steps

1. Create new .gitignore files for each branch and name it like this : .gitignore.branch_name
2. In your git repo, go to .git/hooks/
3. Edit or create post-checkout file and copy the content found in this gist.
4. Don't forget to make it executable with chmod 755 post-checkout
5. Just go to the branch you want and type git status: TADAAA !

post-checkout

#!/bin/sh

old_ref=$1
new_ref=$2
branch_switched=$3

if [[ $branch_switched != '1' ]]
then
    exit 0
fi
echo "---- POST CHECKOUT ----"
current_branch=$(git rev-parse --abbrev-ref HEAD)
hook_dir=$(dirname $0)
root_dir="$(pwd -P)"
info_dir="$root_dir/.git/info"

exclude_target='.gitignore'
if [[ -f "$root_dir/$exclude_target.$current_branch" ]]
then
	echo "Prepare to use .gitignore.$current_branch as exclude file"
    exclude_target=.gitignore.$current_branch
fi
cd "$info_dir"
rm exclude
#ln -s $exclude_target exclude
echo "Copy .gitignore.$current_branch file in place of exclude"
cp "$root_dir/$exclude_target" exclude
echo "--- POST CHECKOUT END ---"

If I push a file in a "private" branch and have that file ignored in the "master" branch, performing a merge of private into master will still commit that file and make it publicly accessible.

Is this working as intended?

I checked that my exclude file has the correct exclusions but it seems like you cannot exclude files from a merge. I read @dberardo-com statement of "limits the power of this solution" as exactly this problem. Is that correct? Is there a solution where I can prevent ignored files from getting merged into the public branch?

@CodeSmile-0000011110110111 The solution is that you create another repository for code changes to the master. That repository accepts changes from the private branch and then changes the .gitignore file before merging into the master branch. You can automate this with GitHub actions.

Also if possible, changes should only move from the master to the private branch.