README.md

Artifact Proxy

This is a tool for proxying Flutter artifacts from a derived Flutter engine revision back to the base Flutter engine revision. This is useful for when you need to modify some of the Flutter artifacts but not all of them.

This is a development tool which map requests to Google Storage (either Shorebird's bucket or the official Flutter buckets).

Usage

Uses config.dart to configure the engine revisions and artifact overrides.

# Run locally with hot-reload enabled.
DEV=true dart --enable-vm-service run bin/server.dart

And then in a separate terminal:

FLUTTER_STORAGE_BASE_URL=http://localhost:8080 flutter precache -a

You should use a separate checkout of Flutter when running this, so you don't poison the cache of your main Flutter checkout.

Updating config.dart

If run into 404s when fetching artifacts, you may need to update the artifact list in config.dart.

To do so, you will need to determine the artifact URLs. Follow these steps:

• Adjust shorebird_cli to point to http://localhost:8080 instead of https://download.shorebird.dev:

  • packages\shorebird_cli\lib\src\shorebird_process.dart

        Map<String, String> _environmentOverrides({
        required String executable,
    }) {
        if (executable == 'flutter') {
        // If this ever changes we also need to update the `shorebird` shell
        // wrapper which downloads runs Flutter to fetch artifacts the first time.
    -      return {'FLUTTER_STORAGE_BASE_URL': 'https://download.shorebird.dev'};
    +      return {'FLUTTER_STORAGE_BASE_URL': 'http://localhost:8080'};
        }
    
        return {};
    }

• Adjust third_party Flutter to point to http://localhost:8080 instead of https://download.shorebird.dev:

  • third_party\flutter\bin\internal\shared.sh

    # Either clones or pulls the Shorebird Flutter repository, depending on whether FLUTTER_PATH exists.
    function update_flutter {
    if [[ -d "$FLUTTER_PATH" ]]; then
        git -C "$FLUTTER_PATH" fetch
    else
        git clone --filter=tree:0 https://github.com/shorebirdtech/flutter.git --no-checkout "$FLUTTER_PATH"
    fi
    # -c to avoid printing a warning about being in a detached head state.
    git -C "$FLUTTER_PATH" -c advice.detachedHead=false checkout "$FLUTTER_VERSION"
    SHOREBIRD_ENGINE_VERSION=`cat "$FLUTTER_PATH/bin/internal/engine.version"`
    echo "Shorebird Engine • revision $SHOREBIRD_ENGINE_VERSION"
    # Install Shorebird Flutter Artifacts
    -  FLUTTER_STORAGE_BASE_URL=https://download.shorebird.dev $FLUTTER_PATH/bin/flutter --version
    +  FLUTTER_STORAGE_BASE_URL=http://localhost:8080 $FLUTTER_PATH/bin/flutter --version
    }

• Modify flutter_tool used by Shorebird to allow downloads from insecure URLs:

  • shorebird\bin\cache\flutter\packages\flutter_tools\gradle\flutter.gradle

    rootProject.allprojects {
        repositories {
            maven {
                url repository
    +           allowInsecureProtocol true
            }
        }
    }

• Remove the flutter_tools snapshot

  cd bin/cache/flutter/bin/cache
  rm flutter_tools.s*

• Run a shorebird command (shorebird run works well)

• For each artifact that 404s, add a line to packages\artifact_proxy\lib\config.dart, following the conventions for capturing engine revisions and escaping relevant characters.

Generating an artifact_manifest.yaml

To generate a new artifact_manifest.yaml for a specific flutter_revision use the following command:

./tools/generate_manifest.sh <flutter_engine_revision> > artifact_manifest.yaml

Then upload the artifact_manifest.yaml to download.shorebird.dev/shorebird/<shorebird_engine_revision>/artifacts_manifest.yaml