Managing multiple codebases or dependencies in a WordPress project can sometimes be a challenge, especially when you have different repositories for themes, plugins, or shared libraries. Git submodules provide a way to incorporate one Git repository into another, making it easier to track, update, and maintain external repositories as part of your main project. While submodules can streamline development workflows, they come with a few quirks that WordPress developers should be aware of.
In this post, we’ll cover:
- What Git submodules are and how they work.
- When and why you might use submodules in WordPress development.
- The challenges of using submodules, and alternatives like Git subtree or package managers.
What Are Git Submodules?
A Git submodule allows you to keep a Git repository as a subdirectory of another repository. Think of it as a way to link one repository inside another, while keeping them separate. The submodule repository has its own commit history and remains an independent project, but the parent repository (in this case, your WordPress site) keeps track of the exact commit of the submodule that it’s pointing to.
Example Use Case for WordPress Developers:
Let’s say you’re building a custom WordPress theme that relies on a shared framework you maintain in a separate repository. Instead of manually copying the framework files into your theme, you can add it as a submodule. This way, you can pull updates from the framework without copying files around.
Why Use Git Submodules in WordPress Development?
Submodules can be helpful for a variety of reasons in WordPress development:
- Shared code libraries: If you’re working with shared PHP libraries, frameworks, or utility functions across multiple themes or plugins, submodules can keep them synced.
- Version control: Submodules allow you to pin your theme or plugin to a specific commit of another repository. This ensures consistency when collaborating with other developers or deploying to production.
- Modular structure: Submodules can help maintain a modular code structure, allowing you to update individual parts of your WordPress site without touching the whole codebase.
Common Git Submodule Workflow
Here’s a quick overview of how you might use Git submodules in a WordPress project:
1. Add a Submodule: Add a submodule to your main WordPress repository (e.g., including a plugin repository within your theme).
git submodule add https://github.com/example/my-plugin.git wp-content/plugins/my-plugin
2. Initialize the Submodule: After cloning a repository with submodules, initialize and update them:
git submodule init git submodule update
3. Updating Submodules: Pull the latest updates from the submodule:
cd wp-content/plugins/my-plugin git pull origin main
4. Commit Changes in the Parent Repo: Once you’ve updated the submodule, you need to commit the updated reference in the parent repository:
git add wp-content/plugins/my-plugin git commit -m "Update my-plugin submodule" git push
Challenges and Limitations
While Git submodules offer some benefits, they can also add complexity, such as:
- Extra Commands: Submodules introduce new Git commands and steps that developers need to remember, which can be confusing if not familiar with the workflow.
- Version Synchronization: The parent repository tracks a specific commit of the submodule. If the submodule changes, you need to manually update the reference in the parent repository.
- Cloning Issues: Developers need to initialize and update submodules after cloning the repository. Forgetting this step leads to missing submodule directories, which can be frustrating for new team members.
Alternatives to Git Submodules
For many WordPress projects, using submodules might feel like overkill. Here are some alternatives to consider:
- Git Subtree: This merges external repositories into your main project, allowing for simpler workflows. You don’t need to manage the submodule separately—it’s treated like any other part of your repository.
- Composer: If you’re managing PHP libraries or dependencies, using Composer to pull in shared libraries or third-party code is a common alternative for WordPress developers.
- Monorepos: Instead of managing multiple repositories with submodules, you can adopt a monorepo approach, where all your themes, plugins, and shared libraries live within a single repository.
By the way, I came across some ideas for alternatives to Git submodules from Atlassian.
Conclusion
While Git submodules can help you manage shared code between WordPress themes, plugins, or external libraries, they do introduce a level of complexity. Understanding the right use cases, as well as the alternatives, is key to maintaining an efficient development workflow. Whether you’re building large custom WordPress sites or working on modular projects, it’s essential to weigh the benefits and challenges of using submodules versus other approaches.