Hot Restartless Code Push with Shorebird in Flutter

Introduction

Shorebird enables true hot restartless code push for Flutter, letting you deliver updates without interrupting user sessions. Unlike traditional Flutter code push approaches that rely on full app restarts or OS-level dynamic delivery, Shorebird integrates at the Dart VM level to apply Dart source and asset diffs in real time. This tutorial dives into advanced techniques for configuring, deploying, and automating restartless over-the-air (OTA) updates using Shorebird.

Setting Up Shorebird for Hot Code Push

Before you begin, ensure you have Shorebird CLI v0.2.0 or later, a Flutter 3.7+ project, and a valid Shorebird app ID.

1. Install Shorebird CLI:

brew tap shorebird-dev/shorebird
brew install shorebird

2. Authenticate and link your project:

shorebird login
cd path/to/flutter_app
shorebird init

3. Enable hot restartless code push by configuring your pubspec.yaml:

shorebird:
  app_id: your_app_id_here
  enable_hot_restartless: true

4. Add the Shorebird runtime plugin in main.dart:

import 'package:flutter/material.dart';
import 'package:shorebird_runtime/shorebird_runtime.dart';

void main() async {
  await ShorebirdRuntime.ensureInitialized();
  runApp(MyApp());
}

With this setup, your app can now fetch and apply patches at startup and during runtime without a full restart.

Implementing Restartless Plugins

Shorebird’s restartless code push mechanism leverages Dart’s isolate model. You can isolate feature modules or hot-swap logic on the fly.

1. Create a plugin-like structure:

// lib/plugins/feature_x.dart
import 'package:flutter/material.dart';
class FeatureX {
  static Widget build() => Text('Feature X v1.0');
}

2. Reference and load dynamically:

// lib/main.dart
import 'package:shorebird_runtime/shorebird_runtime.dart';
import 'plugins/feature_x.dart' as fx;

void showFeature(BuildContext context) async {
  final updated = await ShorebirdRuntime.tryApplyPatch('feature_x');
  if (updated) {
    // reload plugin isolate
    fx.FeatureX.build();
  }
}

3. When you prepare a new release, modify lib/plugins/feature_x.dart and create a new Shorebird patch:

shorebird release create \
  --patch-version 1.1.0 \
  --artifact lib/plugins/feature_x.dart
shorebird release upload --artifact-path

Shorebird will generate a binary diff that clients download on resume, applying the update without restarting app state.

Automating Code Push with CI/CD

Integrate Flutter code push into your pipeline for zero-touch deployments:

1. In your GitHub Actions workflow:

name: Code Push
on: [push]
jobs:
  release:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v3
      - uses: subosito/flutter-action@v2
      - run: flutter pub get
      - run: shorebird auth --api-key ${{ secrets.SHOREBIRD_API_KEY }}
      - run: |
          shorebird release create \
            --patch-version ${{ github.sha }} \
            --artifact lib/
      - run

2. Secure your CI with environment variables for SHOREBIRD_API_KEY and APP_ID.

3. Validate with smoke tests and metadata tagging so shards of your user base receive staggered rollouts.

Automated pipelines make code push for Flutter frictionless and error-resilient.

Best Practices and Troubleshooting

• Modularize features: split heavy logic into distinct Dart libraries. Smaller diffs reduce download time.

• Monitor patch success rates through Shorebird Dashboard. Track failures to revert broken patches.

• Use ShorebirdRuntime.onPatchApplied callbacks to gracefully handle edge cases when hot code push cannot apply (e.g., unsupported asset types).

• When debugging, enable detailed logs with:

  shorebird runtime --verbose

• Maintain backward compatibility: avoid removing fields or method signatures. For breaking changes, bump the app version and schedule a full store release.

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Conclusion

Hot restartless code push with Shorebird revolutionizes how Flutter developers deliver bug fixes and incremental features. By integrating the Shorebird runtime, organizing your code into dynamic modules, and automating deployment pipelines, you achieve near-instant OTA updates that respect active user sessions. Embrace this workflow to accelerate your release cadence and respond rapidly to user feedback, all without forcing app restarts or full downloads.