Flavor-conditional asset bundling does not work when declared within a direct main path dependencies

[alestiago]

Description

Flutter 3.22 introduced “Flavor-conditional asset bundling”, read more about them in the “Conditionally bundling assets based on flavor” documentation.

When declaring assets outside of the main application package and defining flavors for them the main application bundle does not account for these assets as expected.

Steps to reproduce

1. Create a new flutter application for Android:

flutter create my_app --platforms android

2. Create a new flutter package:

flutter create my_app/packages/my_assets --template package

3. Add “package:my_assets” as a direct main dependency on “package:my_app”:

flutter pub add 'my_assets:{"path":"my_app/packages/my_assets"}' --directory my_app

4. Create new assets directories in “package:my_app” and “package:my_assets”:

mkdir my_app/assets
mkdir my_app/packages/my_assets/assets

5. Save new assets on each assets directory, such that:

my_app/
├─ assets/
│  ├─ my_app_logo.png
│  ├─ my_app_logo-dev.png
│  ├─ my_app_logo-prod.png
├─ packages/
│  ├─ my_assets/
│  │  ├─ assets/
│  │  │  ├─ my_assets_logo-dev.png
│  │  │  ├─ my_assets_logo-prod.png
│  │  │  ├─ my_assets_logo.png

6. Declare the assets as flavored assets in “package:my_app”:

# file: my_app/pubspec.yaml

# ...

flutter:
 assets:
   - assets/my_app_logo.png
   - path: assets/my_app_logo-dev.png
     flavors:
       - dev
   - path: assets/my_app_logo-prod.png
     flavors:
       - prod

7. Declare the assets as flavored assets in “package:my_assets”:

# file: my_app/packages/my_assets/pubspec.yaml

# ...

flutter:
 assets:
   - assets/my_assets_logo.png
   - path: assets/my_assets_logo-dev.png
     flavors:
       - dev
   - path: assets/my_assets_logo-prod.png
     flavors:
       - prod

8. Define “dev” and “prod” Android flavors in “my_app/android/app/build.gradle”:

android {
   // ...

   flavorDimensions "default"

   productFlavors {
       dev {
           dimension "default"
           resValue "string", "app_name", "dev flavor example"
           applicationIdSuffix ".dev"
       }
       prod {
           dimension "default"
           resValue "string", "app_name", "prod flavor example"
           applicationIdSuffix ".prod"
       }
   }
}

9. Bundle the main application as an APK:

flutter build apk --flavor dev

10. Analyze the generated APK using Android Studio’s APK Analyzer.

The built APK is expected to be at: my_app/build/app/outputs/flutter-apk/app-dev-release.apk

Expected results

my_assets_logo-dev.png should have also been bundled in the APK but it was not.

Actual results

The following assets were included in the APK:

• my_app_logo.png
• my_assets_logo.png

Code sample

Not applicable, see reproductive steps instead.

Screenshots or Video

Actual APK Analyzer results

Logs

Not applicable.

Flutter Doctor output

Doctor output

[✓] Flutter (Channel stable, 3.24.3, on macOS 14.7 23H124 darwin-arm64, locale en-US)
    • Flutter version 3.24.3 on channel stable at /Users/alestiago-nbcu/Developer/flutter
    • Upstream repository https://github.com/flutter/flutter.git
    • Framework revision 2663184aa7 (2 weeks ago), 2024-09-11 16:27:48 -0500
    • Engine revision 36335019a8
    • Dart version 3.5.3
    • DevTools version 2.37.3

[✓] Android toolchain - develop for Android devices (Android SDK version 35.0.0)
    • Android SDK at /Users/alestiago-nbcu/Library/Android/sdk
    • Platform android-35, build-tools 35.0.0
    • Java binary at: /Applications/Android Studio.app/Contents/jbr/Contents/Home/bin/java
    • Java version OpenJDK Runtime Environment (build 17.0.11+0-17.0.11b1207.24-11852314)
    • All Android licenses accepted.

[✓] Xcode - develop for iOS and macOS (Xcode 15.4)
    • Xcode at /Applications/Xcode.app/Contents/Developer
    • Build 15F31d
    • CocoaPods version 1.15.2

[✓] Chrome - develop for the web
    • Chrome at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome

[✓] Android Studio (version 2024.1)
    • Android Studio at /Applications/Android Studio.app/Contents
    • Flutter plugin can be installed from:
      🔨 https://plugins.jetbrains.com/plugin/9212-flutter
    • Dart plugin can be installed from:
      🔨 https://plugins.jetbrains.com/plugin/6351-dart
    • Java version OpenJDK Runtime Environment (build 17.0.11+0-17.0.11b1207.24-11852314)

[✓] VS Code (version 1.93.1)
    • VS Code at /Applications/Visual Studio Code.app/Contents
    • Flutter extension version 3.96.0

[✓] Connected device (3 available)
    • macOS (desktop)                 • macos                 • darwin-arm64   • macOS 14.7 23H124 darwin-arm64
    • Mac Designed for iPad (desktop) • mac-designed-for-ipad • darwin         • macOS 14.7 23H124 darwin-arm64
    • Chrome (web)                    • chrome                • web-javascript • Google Chrome 129.0.6668.60

[✓] Network resources
    • All expected network resources are available.

• No issues found!

[huycozy]

Hi @alestiago
I think the problem comes from assets path. Per the example on the docs, you should create separate directories for each flavors, for eg:

flutter:
 assets:
   - assets/common/
   - path: assets/dev/
     flavors:
       - dev
   - path: assets/prod/
     flavors:
       - prod

├── assets
│   ├── common
│   │   └── flutter.jpeg
│   ├── dev
│   │   └── flutter.jpeg
│   └── prod
│       └── flutter.jpeg

And similar assets declaration in the package. Can you try to see if it works?

[alestiago]

Hi @huycozy, thanks for chiming in.

Your suggestion is invalid, it does not bundle the flavored assets when defined in a dependency package, see below details for additional information.

Additional information

For clarity, this was the new directory structure:

my_app/
├─ assets/
│  ├─ my_app_logo.png
│  ├─ my_app_logo-dev.png
│  ├─ my_app_logo-prod.png
├─ packages/
│  ├─ my_assets/
│  │  ├─ assets/
│  │  │  ├─ my_assets_logo.png
│  │  │  ├─ dev/
│  │  │  │  ├─ my_assets_logo-dev.png
│  │  │  ├─ prod/
│  │  │  │  ├─ my_assets_logo-prod.png

This was the new pubspec within the package:my_assets:

# file: my_app/packages/my_assets/pubspec.yaml

flutter:
  assets:
    - assets/my_assets_logo.png
    - path: assets/dev/
      flavors:
        - dev
    - path: assets/prod/
      flavors:
        - prod

And this was the examined APK after being built with:

flutter build apk --flavor dev

NOTE: Regardless if it can only accept directories in dependencies or not (which also failed) what has been described in the issue is clearly showing inconsistent behavior in pubspecs when using flavor-conditional bundling. The same syntax was used for the main application package and the direct main dependency package, and the conditional bundling only worked as expected for the main application package.

[huycozy]

Thanks for your response. I can also see the issue with my assets structure. When building apk with flavor, conditionally bundling does not work on package.

My assets structure

.
├── assets
│   ├── common
│   │   └── flutter.jpeg
│   ├── dev
│   │   └── flutter-dev.jpeg
│   └── prod
│       └── flutter-prod.jpeg
├── packages
│   └── my_assets
│       ├── assets
│       │   ├── common
│       │   │   └── flutter.jpeg
│       │   ├── dev
│       │   │   └── flutter-dev.jpeg
│       │   └── prod
│       │       └── flutter-prod.jpeg

Output APK analysis

The complete sample project: flutter-flavor-conditionally-bundling-assets. Reproduced on Flutter master 3.26.0-1.0.pre.263.

[bkonyi]

FYI @andrewkolos

[feduke-nukem]

I would like to point out that this issue is not specific only to Android, as it also arises on iOS, according to #155404.

[huycozy]

Thank @feduke-nukem. Taking off Android label as this concerns a tool issue in general.

[andrewkolos]

This fix should be available in the next Flutter release (3.27 as far as I'm aware), starting with the beta branch.

[github-actions]

This thread has been automatically locked since there has not been any recent activity after it was closed. If you are still experiencing a similar issue, please open a new bug, including the output of flutter doctor -v and a minimal reproduction of the issue.