Git attributes

GitLab supports defining custom Git attributes such as what files to treat as binary, and what language to use for syntax highlighting diffs.

To define these attributes, create a file called .gitattributes in the root directory of your repository and push it to the default branch of your project.

Encoding requirements

The .gitattributes file must be encoded in UTF-8 and must not contain a Byte Order Mark. If a different encoding is used, the file’s contents are ignored.

Support for mixed file encodings

GitLab attempts to detect the encoding of files automatically, but defaults to UTF-8 unless the detector is confident of a different type (such as ISO-8859-1). Incorrect encoding detection can result in some characters not displaying in the text, such as accented characters in a non-UTF-8 encoding.

Git has built-in support for handling this eventuality and automatically converts files between a designated encoding and UTF-8 for the repository itself. Configure support for mixed file encoding in the .gitattributes file using the working-tree-encoding attribute.

Example: 

*.xhtml text working-tree-encoding=ISO-8859-1

With this example configuration, Git maintains all .xhtml files in the repository in ISO-8859-1 encoding in the local tree, but converts to and from UTF-8 when committing into the repository. GitLab renders the files accurately as it only sees correctly encoded UTF-8.

If applying this configuration to an existing repository, files may need to be touched and recommitted if the local copy has the correct encoding but the repository does not. This can be performed for the whole repository by running git add --renormalize ..

For more information, see working-tree-encoding.

Syntax highlighting

The .gitattributes file can be used to define which language to use when syntax highlighting files and diffs. For more information, see Syntax highlighting.

Custom merge drivers

Ability to configure custom merge drivers through GitLab introduced in GitLab 15.10.

GitLab self-managed instance administrators can define custom merge drivers in a GitLab configuration file, then use the custom merge drivers in a Git .gitattributes file. Custom merge drivers are not supported on GitLab.com.

You might configure a custom merge driver, for example, if there are certain files that should be ignored during a merge such as build files and configuration files.

Configure a custom merge driver

The following example illustrates how to define and use a custom merge driver in GitLab.

How to configure a custom merge driver depends on the type of installation.

Linux package (Omnibus)
  1. Edit /etc/gitlab/gitlab.rb.

  2. Add configuration similar to the following: 

    gitaly['configuration'] = {
  # ...
  git: {
    # ...
    config: [
      # ...
      { key: "merge.foo.driver", value: "true" },
    ],
  },
}
Self-compiled (source)
  1. Edit gitaly.toml.

  2. Add configuration similar to the following: 

    [[git.config]]
key = "merge.foo.driver"
value = "true"

In this example, during a merge, Git uses the driver value as the command to execute. In this case, because we are using true with no arguments, it always returns a non-zero return code. This means that for the files specified in .gitattributes, merges do nothing.

To use your own merge driver, replace the value in driver to point to an executable. For more details on how this command is invoked, see the Git documentation on custom merge drivers.

Use .gitattributes to set files custom merge driver applies to

In a .gitattributes file, you can set the paths of files you want to use with the custom merge driver. For example: 

config/* merge=foo

In this case, every file under the config/ folder uses the custom merge driver called foo defined in the GitLab configuration.