# Flutter SDK Docker Images

<a href="https://git.openharbor.io/svrnty/docker-flutter-sdk" target="_blank"><img src="https://img.shields.io/badge/Git-Repository-orange?logo=gitea" alt="Git Repository"></a>
<a href="https://wolfi.dev" target="_blank"><img src="https://img.shields.io/badge/Base-Wolfi-purple?logo=linux" alt="Wolfi"></a>

Lightweight Flutter SDK images for CI/CD pipelines. Built on [Wolfi](https://wolfi.dev), a security-focused Linux distribution designed for containers.

## Variants

- `web` - Web/WASM builds
- `android` - Android APK/AAB builds
- `linux` - Linux desktop builds

All variants support `linux/amd64` and `linux/arm64`.

## Why Wolfi?

[Wolfi](https://wolfi.dev) is a lightweight Linux distribution built specifically for containers. It provides:

- **Minimal footprint** - Only essential packages, nothing extra
- **Daily security updates** - Patches applied quickly
- **Designed for containers** - No legacy cruft from traditional distros

## Features

- **Lightweight** - Optimized for fast CI/CD pulls
- **Secure** - Built on Wolfi with continuous vulnerability scanning
- **Multi-arch** - Supports both `linux/amd64` and `linux/arm64`
- **Non-root** - Runs as unprivileged user (UID 65532)
- **Supply chain security** - SBOM and SLSA provenance attestations included

## Dockerfile Examples

### Web App (WASM)

```dockerfile
FROM svrnty/flutter-sdk:web-latest AS build
WORKDIR /app
COPY . .
RUN flutter pub get && flutter build web --wasm --release

# Cache-busting: append version to JS/WASM references
RUN VERSION=$(date +%s) && cd build/web && \
    sed -i "s|flutter_bootstrap\.js\"|flutter_bootstrap.js?v=${VERSION}\"|g" index.html && \
    sed -i "s|main\.dart\.js\"|main.dart.js?v=${VERSION}\"|g" flutter_bootstrap.js && \
    sed -i "s|main\.dart\.mjs\"|main.dart.mjs?v=${VERSION}\"|g" flutter_bootstrap.js && \
    sed -i "s|main\.dart\.wasm\"|main.dart.wasm?v=${VERSION}\"|g" flutter_bootstrap.js

FROM ghcr.io/static-web-server/static-web-server:2 AS sws
FROM scratch
COPY --from=sws /static-web-server /static-web-server
COPY --from=build /app/build/web /public
COPY sws.toml /sws.toml
EXPOSE 8080
USER 65534
ENTRYPOINT ["/static-web-server", "--config-file", "/sws.toml"]
```

**sws.toml** - Required headers for WASM multi-threading:

```toml
[general]
host = "0.0.0.0"
port = 8080
root = "/public"
page-fallback = "/public/index.html"
compression = true

[[advanced.headers]]
source = "**"
[advanced.headers.headers]
Cross-Origin-Opener-Policy = "same-origin"
Cross-Origin-Embedder-Policy = "require-corp"
```

### Android APK

```dockerfile
FROM svrnty/flutter-sdk:android-latest AS build
WORKDIR /app
COPY . .
RUN flutter pub get && flutter build apk --release

FROM scratch
COPY --from=build /app/build/app/outputs/flutter-apk/app-release.apk /
```

### Linux Desktop

```dockerfile
FROM svrnty/flutter-sdk:linux-latest AS build
WORKDIR /app
COPY . .
RUN flutter pub get && flutter build linux --release

FROM debian:bookworm-slim
RUN apt-get update && apt-get install -y libgtk-3-0 && rm -rf /var/lib/apt/lists/*
COPY --from=build /app/build/linux/arm64/release/bundle /app
ENTRYPOINT ["/app/my_app"]
```

## CI/CD (Gitea/GitHub Actions)

```yaml
jobs:
  build:
    runs-on: ubuntu-latest
    container:
      image: svrnty/flutter-sdk:android-latest
    steps:
      - uses: actions/checkout@v4
      - run: flutter pub get
      - run: flutter build apk --release
```

## Tags

- `<variant>-latest` - Latest stable Flutter release
- `<variant>-<version>` - Specific Flutter version (e.g., `android-3.29.0`)

## Automatic Updates

Images are automatically rebuilt when:
- New Flutter stable versions are released
- Base image security updates are available

Every build is scanned and includes supply chain attestations (SBOM, SLSA provenance).

## License

MIT