Setting Up Monorepo Management for Flutter with Melos

Introduction

Managing multiple Flutter packages and apps in a single repository can streamline your development workflow, enforce consistent tooling, and simplify dependency sharing. Monorepo setups avoid version drift between libraries, accelerate local testing, and improve CI performance. Melos is a CLI tool specifically designed to orchestrate, manage scripts, and handle dependencies in Dart and Flutter monorepos. In this tutorial, we’ll walk through setting up Melos in a Flutter monorepo, structuring workspaces, running custom scripts, and integrating with CI/CD pipelines. By the end, you'll have a robust, maintainable monorepo foundation for your Flutter mobile development projects.

Installing Melos and Initializing Your Monorepo

First, ensure you have Dart and Flutter SDKs installed. Then globally activate Melos:

dart pub global activate melos

Or with Flutter:

flutter pub global activate melos

Next, create a new repository structure:

mkdir flutter_monorepo && cd flutter_monorepo
git init
mkdir packages apps

Inside the root, add a melos.yaml to configure packages and workspace policies:

dir:
  packages:
    - 'packages/*'
    - 'apps/*'
name: flutter_monorepo
enablePublish: false

Run melos bootstrap to install dependencies across all packages and apps. Melos will detect each pubspec, link local paths, and ensure a single lock file at the root.

Structuring Projects and Workspaces

Melos treats each pubspec folder as a workspace. Organize shared utilities and UI components under packages/, and Flutter applications under apps/. For example:

flutter_monorepo/
├─ packages/
│  ├─ ui_components/
│  └─ data_models/
└─ apps/
   ├─ app_a/
   └─ app_b

In packages/ui_components/pubspec.yaml, reference data_models as a path dependency:

dependencies:
  flutter:
    sdk: flutter
  data_models:
    path

After updating pubspecs, rerun melos bootstrap. All workspaces now share a single package resolution, making cross-package references seamless.

Managing Dependencies and Scripts

Melos simplifies running commands across all workspaces. Define scripts in melos.yaml under a scripts: section:

scripts:
  analyze:
    run: dart analyze .
  test:
    run: flutter test --coverage
  format:
    run

Invoke melos run analyze to run Dart analysis in every package and app. To run only in specific folders, use melos exec:

melos exec --scope=ui_components -- flutter test

You can also create custom scripts in Dart for code generation or other tasks. For example, a simple build script in tool/build.dart:

// tool/build.dart
import 'dart:io';
void main(List<String> args) {
  Process.runSync('flutter', ['pub', 'run', 'build_runner', 'build'],
      runInShell: true, stdout: stdout, stderr: stderr);
}

Then add it to Melos:

  build:
    run

Integrating CI/CD Pipelines

In your CI workflow (GitHub Actions, GitLab CI, etc.), use Melos to bootstrap and run scripts in a cached environment. Example GitHub Actions snippet:

name: CI
on: [push, pull_request]
jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v2
      - name: Setup Flutter
        uses: subosito/flutter-action@v2
      - name: Install Melos
        run: flutter pub global activate melos
      - name: Bootstrap Monorepo
        run: melos bootstrap --no-utf-8
      - name: Run Analyzer
        run: melos run analyze
      - name: Run Tests
        run

Cache .pub-cache and ~/.pub-cache directories to speed up builds. This pipeline ensures consistent analysis, formatting, testing, and build steps across every package and app.

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Conclusion

Melos brings order and automation to Flutter monorepos, making it easy to share code, enforce standards, and orchestrate workflows. By installing Melos, defining clear workspaces, and setting up scripts, you gain a centralized management layer for dependencies, tests, and builds. Integrating Melos into your CI/CD pipelines maintains consistency across projects and accelerates development velocity. Adopt Melos today to streamline your Flutter mobile development and unlock the full potential of monorepo architecture.