Melos - Manage your Dart Projects with Monorepo

Have you ever struggled with managing multiple packages or libraries within a Dart project? If you have, you know how challenging it can be to handle dependencies, configurations, and versioning across different packages. This is where Melos comes in.

In this blog post, we’ll explore what Melos is, its pros and cons, and how you can use it to streamline your development process.

What is Melos?

Melos is a powerful tool for managing Dart projects as monorepos, providing a simple and efficient way to manage multiple packages and libraries under a single codebase. Melos is designed to help manage these challenges by providing a streamlined workflow for building, testing, and managing dependencies across all projects in the monorepo.

Melos provides a command-line interface (CLI) that allows you to run scripts across all projects in the monorepo. For example, you can run the same build or test script across all projects, or you can run a script that installs dependencies for all projects. This makes it easy to manage dependencies and keep all projects in sync.

Melos also provides a plugin system (for Intellij and VS Code) that allows you to extend its functionality. Plugins can be used to add support for new languages, tools, or workflows, or to customize the behavior of existing commands.

Overall, Melos can be a powerful tool for managing monorepo projects. Its streamlined workflow and plugin system make it easy to manage dependencies and build and test multiple projects in a single repository.

What are the pros & cons of Melos?

Here are some of the pros and cons of using Melos to manage Dart projects as a monorepo:

Pros:

1. Simplified dependency management: With Melos, you can easily manage dependencies across multiple packages within a monorepo. This helps reduce conflicts and ensures that all packages use the same version of dependencies, making it easier to maintain and update your codebase.
2. Consistent development environment: Melos allows you to ensure that all packages within your monorepo are using the same version of Dart and other dependencies. This helps reduce compatibility issues and streamlines the development process, ensuring that everyone is working with the same tools and resources.
3. Streamlined release process: Melos simplifies the process of publishing packages within your monorepo to the pub.dev registry. This saves time and ensures that all packages are updated with the latest features and bug fixes.
4. Enhanced collaboration: Monorepos can promote collaboration between teams and simplify the sharing of code and resources. With Melos, you can easily manage these shared resources and ensure that they are up-to-date and compatible, making it easier for multiple developers to work on the same codebase simultaneously.

Cons:

1. Learning curve: Melos can be challenging to learn, especially for developers who are new to monorepo concepts or are unfamiliar with the command-line interface.
2. Limited flexibility: Melos requires that you structure your project in a specific way, which may limit your flexibility and make it harder to customize your project structure to fit your needs.
3. Increased complexity: Managing multiple packages and libraries within a single codebase can increase the complexity of your project, making it harder to maintain and troubleshoot.

Installation:

To make Melos accessible from any location on your system, install it as a global package using pub.dev. It is a one-time step.

dart pub global activate melos

Setup in your project:

Melos is intended to be used with a workspace, which is a folder that contains all the packages that will be developed simultaneously. The root directory of the workspace must havemelos.yamlfile.

name: new_widgets

packages:
  - packages/*

scripts:
  analyze:
    exec: dart analyze .

Execute the command:

To run the script which is written in melos.yaml use following command:

melos run analyze .

And it will give you the output as below:

Melos — Output after running a melos command successfully.

So this is very basic example in which you learned that how what is Melos, Its pros/cons, and basic example. We will check more examples in next blog.

Before wrapping up, I would like to share some useful links about Melos:

• Official Documentation
• The best example of Melos that I’ve ever seen: FlutterFire

Melos used by (Source):

• Flame-Engine/Flame
• aws-amplify/amplify-flutter
• fluttercommunity/plus_plugins
• GetStream/stream-chat-flutter
• 4itworks/opensource_qwkin_dart
• gql-dart/ferry
• cbl-dart/cbl-dart
• ema987/paddinger
• flutter-stripe/flutter_stripe
• kmartins/groveman
• ApptiveGrid/apptive_grid_flutter
• flutternetwork/WiFiFlutter
• iapicca/yak_packages
• atsign-foundation/at_app
• sub6resources/flutter_html
• ferraridamiano/ConverterNOW
• rrifafauzikomara/youtube_video

If you’re working on a Dart Monorepo project, I highly recommend giving Melos a try. With its powerful features, intuitive interface, and strong community support, it’s an excellent choice for managing even the most complex projects.

So don’t hesitate to reach out and get involved in the Melos community today!

I will try to explore more about Melos and share with you in next blog, You can also comment if you are going to try and share your feedback later.

Don’t forget to clap, I know you can clap for 50 times. 👏 😎

Keep packaging with Melos 🎉