Creating Patches

It can happen that you may need to manually modify an external dependency for it to work correctly in the context of a Omnibus embedded packaging, or even to fix an issue that the upstream maintainer have not either accepted or still taking longer to review and ship.


Omnibus has a specific DSL and conventions to ship and apply patches automatically as part of the building process.

You will store .patch files that contain the changes in a specific directory structure and with the help of the patch DSL method, will apply the file(s) to reflect the desired changes:


As example, for a patch that will be applied during the execution of gitlab-rails, you will store .patch files in:


Creating a patch

There are two easy ways to create a patch file. You can use the diff command and compare a original with a modified file (i.e. target.rb with target.rb.original) or you can use Git to output a patch based one or more commits.

Diff command

To create a patch file using the diff and the previous example, duplicate the file you are changing with a new name, and make the change to the old one.

diff -Naur target.rb.original target.rb > my_awesome_change.patch

Git command

To create a patch file based on Git commits, you must get the hash from both (or just the earliest one if you are comparing with base HEAD).

# to generate a patch between two commits
git diff commitid1 commitid2 > my_awesome_change.patch

# to generate a patch between the HEAD and a specific commits
git diff commitid1 > my_awesome_change.patch

Using the patch

To patch one or more files, you must first execute any operation in your software definition that provides the original files like downloading, bundle installing etc, and then add something similar to:

patch source: 'my_awesome_change.patch', target: "#{install_dir}/embedded/target_file.txt"