Git: git-deploy

Fortunately git is easy to extend. I'd like to share a very short but useful git extension with you: git-deploy. If you didn't know, git can easily be extended by having an executable on your path with the git- prefix. Therefore, an executable file named git-cats can be invoked via git cats, git-scrub via git scrub and so forth.

We're using a short shell script to generate a zip file that contains only the differences from the last deploy. In this manner it's easy for us to transfer only those files that have changed. The limitations of this approach are that deletes are not included, nor are database changes (obviously).

The script follows:

#!/bin/sh

if [ -z "$1" ]
then
    echo "usage: $0 <from> [to-file]"
    exit
fi

patch_file="$2"
if [ -z "$patch_file" ]
then
    patch_file="patch.zip"
fi

git archive --format=zip HEAD $(git diff-tree -r --name-only --diff-filter=AM $1..HEAD) > $patch_file            
    

To use this script copy it into your path so that it is executable. Give it a whirl by typing: git deploy. It should give you a warning such as: usage: git-deploy <from> [to-file].

The script works by comparing a given commit against the head, and stuffing the difference into a zip archive called patch.zip. This process works very well with tags, especially if each release is tagged appropriately. Be sure that the commit specified is an ancestor of the current head, otherwise you may end up with an archive of everything in HEAD.