Git Submodules

Advanced Git

Amanda Crawford-Adamo

Software and Data Engineer

What is a Git Submodule?

Git Submodule

git submodule

A depiction of a repo with multiple repository within it.

Adding a submodule using the link or directory under path folder.

git submodule add <repository link|dir> <path>

Example

Adds the data validator library to the ETL project under the libs/validator folder in the ETL repo.

git submodule add https://github.com/example/data-validator.git libs/validator

List all submodules in a project

git submodule status

Example

$ git submodule status
e1f2...7w8x9 data_cleaning_lib
a1b2...q7r8 api_connector
d9e8...t3u2 visualization_toolkit

Update submodule with the latest changes

There are several options:

Updates all submodules where the source code is on your local computer.
```
git submodule update --init 
```
Updates all submodule where the source code is on a remote repo.
```
git submodule update --init --remote 
```

Updates a specific submodules

git submodule update --init <path_to_submodule>

Remove a submodule process

Copy all files that need to be in the new submodule repo into another folder outside the repo.
Inside the new folder, create a new repository for the submodule:
```
git init <new-submodule>
```
Use git filter-repo to extract the relevant files and history from the main project:
```
git filter-repo --path <extract_path> --invert-paths
```

Add the extracted repository as a submodule to the main project:

git submodule add <new-submodule_path> <path_to_store_submodule>

Use cases:

Best practices:

Advanced Git