Migrate to Wolfi base image and optimize SDK size

- Switch all Dockerfiles from debian:bookworm-slim to svrnty/base-distro:flutter-sdk-latest (Wolfi)
- Use non-root user (UID 65532) instead of custom flutter user
- Strip wrong-platform engine artifacts per variant (web, android, linux)
- Remove dev/, examples/ and compact .git with git gc --prune=all
- Android: multi-stage build for JDK 17 + Android SDK 36 from Debian
- Linux: multi-stage build for clang/cmake/ninja/GTK3 with glibc conflict resolution
- Update Android SDK from 35 to 36 (required by Flutter 3.38.9)

Image sizes: web 1.32 GB, linux 2.43 GB, android 4.22 GB
(down from 4.9 GB, 3.69 GB, 4.15 GB respectively)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Dockerfile

@@ -1,31 +1,29 @@
-FROM debian:bookworm-slim
+FROM svrnty/base-distro:flutter-sdk-latest
 
 ARG FLUTTER_VERSION=3.38.9
 
-LABEL org.opencontainers.image.title="flutter-sdk"
+LABEL org.opencontainers.image.title="flutter-sdk-web"
 LABEL org.opencontainers.image.description="Minimal Flutter SDK for Web/WASM CI builds"
 LABEL org.opencontainers.image.version="${FLUTTER_VERSION}"
 
-# Install minimal dependencies for Flutter web builds
-RUN apt-get update && apt-get install -y --no-install-recommends \
-    curl \
-    git \
-    unzip \
-    xz-utils \
-    ca-certificates \
-    && rm -rf /var/lib/apt/lists/*
+USER 0
 
-ENV FLUTTER_HOME=/opt/flutter
-ENV PATH="${FLUTTER_HOME}/bin:${FLUTTER_HOME}/bin/cache/dart-sdk/bin:${PATH}"
-
-# Download Flutter SDK from official archive
+# Download Flutter SDK and strip unnecessary files in a single layer
 RUN curl -fsSL "https://storage.googleapis.com/flutter_infra_release/releases/stable/linux/flutter_linux_${FLUTTER_VERSION}-stable.tar.xz" \
       -o /tmp/flutter.tar.xz && \
     tar xf /tmp/flutter.tar.xz -C /opt && \
-    rm /tmp/flutter.tar.xz
+    rm /tmp/flutter.tar.xz && \
+    rm -rf /opt/flutter/dev \
+           /opt/flutter/examples \
+           /opt/flutter/bin/cache/artifacts/engine/android-* \
+           /opt/flutter/bin/cache/artifacts/engine/linux-* && \
+    chown -R 65532:65532 /opt/flutter
 
-# Mark git directory as safe (tarball is owned by different uid)
-RUN git config --global --add safe.directory "${FLUTTER_HOME}"
+# Mark git directory as safe and compact git history
+RUN git config --global --add safe.directory /opt/flutter && \
+    cd /opt/flutter && git gc --prune=all
+
+USER 65532
 
 # Configure for web-only (disable everything else)
 RUN flutter config --enable-web \
@@ -48,10 +46,4 @@ RUN flutter precache --web \
 # Verify installation
 RUN flutter doctor -v
 
-# Create non-root user for CI builds
-RUN groupadd -r flutter && useradd -r -g flutter -m -d /home/flutter flutter && \
-    chown -R flutter:flutter "${FLUTTER_HOME}" /home/flutter
-
 WORKDIR /app
-RUN chown flutter:flutter /app
-USER flutter

Dockerfile.android

@@ -1,27 +1,30 @@
-FROM debian:bookworm-slim
+FROM svrnty/base-distro:flutter-sdk-latest AS base
 
 ARG FLUTTER_VERSION=3.38.9
 ARG ANDROID_SDK_TOOLS_VERSION=11076708
-ARG ANDROID_COMPILE_SDK=35
-ARG ANDROID_BUILD_TOOLS=35.0.1
+ARG ANDROID_COMPILE_SDK=36
+ARG ANDROID_BUILD_TOOLS=36.0.0
 
-LABEL org.opencontainers.image.title="flutter-sdk"
+LABEL org.opencontainers.image.title="flutter-sdk-android"
 LABEL org.opencontainers.image.description="Flutter SDK for Android CI builds"
 LABEL org.opencontainers.image.version="${FLUTTER_VERSION}"
 
-# Install dependencies for Flutter + Android SDK
+# --- Install JDK and Android SDK in debian (requires apt + shared libs) ---
+FROM debian:bookworm-slim AS android-stage
+
+ARG ANDROID_SDK_TOOLS_VERSION=11076708
+ARG ANDROID_COMPILE_SDK=36
+ARG ANDROID_BUILD_TOOLS=36.0.0
+
 RUN apt-get update && apt-get install -y --no-install-recommends \
     curl \
-    git \
     unzip \
-    xz-utils \
-    ca-certificates \
     openjdk-17-jdk-headless \
     && rm -rf /var/lib/apt/lists/*
 
-# Android SDK
+ENV JAVA_HOME=/usr/lib/jvm/java-17-openjdk-amd64
 ENV ANDROID_HOME=/opt/android-sdk
-ENV PATH="${ANDROID_HOME}/cmdline-tools/latest/bin:${ANDROID_HOME}/platform-tools:${PATH}"
+ENV PATH="${JAVA_HOME}/bin:${ANDROID_HOME}/cmdline-tools/latest/bin:${ANDROID_HOME}/platform-tools:${PATH}"
 
 RUN mkdir -p "${ANDROID_HOME}/cmdline-tools" && \
     curl -fsSL "https://dl.google.com/android/repository/commandlinetools-linux-${ANDROID_SDK_TOOLS_VERSION}_latest.zip" \
@@ -30,25 +33,48 @@ RUN mkdir -p "${ANDROID_HOME}/cmdline-tools" && \
     mv /tmp/cmdline-tools/cmdline-tools "${ANDROID_HOME}/cmdline-tools/latest" && \
     rm -rf /tmp/cmdline-tools.zip /tmp/cmdline-tools
 
-# Accept licenses and install SDK components
 RUN yes | sdkmanager --licenses > /dev/null 2>&1 && \
     sdkmanager --install \
       "platform-tools" \
       "platforms;android-${ANDROID_COMPILE_SDK}" \
       "build-tools;${ANDROID_BUILD_TOOLS}"
 
-# Flutter SDK
-ENV FLUTTER_HOME=/opt/flutter
-ENV PATH="${FLUTTER_HOME}/bin:${FLUTTER_HOME}/bin/cache/dart-sdk/bin:${PATH}"
+# --- Build final image ---
+FROM base
 
+USER 0
+
+# Copy JDK and its required shared libraries from debian
+COPY --from=android-stage /usr/lib/jvm/java-17-openjdk-amd64 /usr/lib/jvm/java-17-openjdk-amd64
+COPY --from=android-stage /usr/lib/x86_64-linux-gnu /usr/lib/x86_64-linux-gnu
+COPY --from=android-stage /lib/x86_64-linux-gnu /lib/x86_64-linux-gnu
+ENV JAVA_HOME=/usr/lib/jvm/java-17-openjdk-amd64
+ENV PATH="${JAVA_HOME}/bin:${PATH}"
+
+# Copy Android SDK (already set up with licenses and components)
+COPY --from=android-stage /opt/android-sdk /opt/android-sdk
+ENV ANDROID_HOME=/opt/android-sdk
+ENV PATH="${ANDROID_HOME}/cmdline-tools/latest/bin:${ANDROID_HOME}/platform-tools:${PATH}"
+
+# Download Flutter SDK and strip unnecessary files in a single layer
 RUN curl -fsSL "https://storage.googleapis.com/flutter_infra_release/releases/stable/linux/flutter_linux_${FLUTTER_VERSION}-stable.tar.xz" \
       -o /tmp/flutter.tar.xz && \
     tar xf /tmp/flutter.tar.xz -C /opt && \
-    rm /tmp/flutter.tar.xz
+    rm /tmp/flutter.tar.xz && \
+    rm -rf /opt/flutter/dev \
+           /opt/flutter/examples \
+           /opt/flutter/bin/cache/artifacts/engine/linux-* \
+           /opt/flutter/bin/cache/flutter_web_sdk
 
-RUN git config --global --add safe.directory "${FLUTTER_HOME}"
+RUN git config --global --add safe.directory /opt/flutter && \
+    cd /opt/flutter && git gc --prune=all
 
-# Configure for Android-only
+# Fix ownership before switching to flutter user
+RUN chown -R 65532:65532 /opt/flutter "${ANDROID_HOME}"
+
+USER 65532
+
+# Configure Flutter for Android-only
 RUN flutter config --enable-android \
     --no-enable-web \
     --no-enable-ios \
@@ -69,10 +95,4 @@ RUN flutter precache --android \
 
 RUN flutter doctor -v
 
-# Create non-root user for CI builds
-RUN groupadd -r flutter && useradd -r -g flutter -m -d /home/flutter flutter && \
-    chown -R flutter:flutter "${FLUTTER_HOME}" "${ANDROID_HOME}" /home/flutter
-
 WORKDIR /app
-RUN chown flutter:flutter /app
-USER flutter

Dockerfile.linux

@@ -1,18 +1,15 @@
-FROM debian:bookworm-slim
+FROM svrnty/base-distro:flutter-sdk-latest AS base
 
 ARG FLUTTER_VERSION=3.38.9
 
-LABEL org.opencontainers.image.title="flutter-sdk"
+LABEL org.opencontainers.image.title="flutter-sdk-linux"
 LABEL org.opencontainers.image.description="Flutter SDK for Linux desktop CI builds"
 LABEL org.opencontainers.image.version="${FLUTTER_VERSION}"
 
-# Install dependencies for Flutter + Linux desktop builds
+# --- Install Linux desktop build deps in debian ---
+FROM debian:bookworm-slim AS deps-stage
+
 RUN apt-get update && apt-get install -y --no-install-recommends \
-    curl \
-    git \
-    unzip \
-    xz-utils \
-    ca-certificates \
     clang \
     cmake \
     ninja-build \
@@ -22,17 +19,69 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
     libstdc++-12-dev \
     && rm -rf /var/lib/apt/lists/*
 
-ENV FLUTTER_HOME=/opt/flutter
-ENV PATH="${FLUTTER_HOME}/bin:${FLUTTER_HOME}/bin/cache/dart-sdk/bin:${PATH}"
+# --- Build final image ---
+FROM base
 
+USER 0
+
+# Download Flutter SDK and strip unnecessary files in a single layer
 RUN curl -fsSL "https://storage.googleapis.com/flutter_infra_release/releases/stable/linux/flutter_linux_${FLUTTER_VERSION}-stable.tar.xz" \
       -o /tmp/flutter.tar.xz && \
     tar xf /tmp/flutter.tar.xz -C /opt && \
-    rm /tmp/flutter.tar.xz
+    rm /tmp/flutter.tar.xz && \
+    rm -rf /opt/flutter/dev \
+           /opt/flutter/examples \
+           /opt/flutter/bin/cache/artifacts/engine/android-* \
+           /opt/flutter/bin/cache/flutter_web_sdk
 
-RUN git config --global --add safe.directory "${FLUTTER_HOME}"
+RUN git config --global --add safe.directory /opt/flutter && \
+    cd /opt/flutter && git gc --prune=all
 
-# Configure for Linux desktop only
+# Remove symlinks that conflict with COPY from debian stage
+RUN rm -f /usr/lib/terminfo
+
+# Copy only specific toolchain binaries (not all of /usr/bin which would overwrite Wolfi's core utils)
+COPY --from=deps-stage /usr/bin/cmake /usr/bin/cmake
+COPY --from=deps-stage /usr/bin/ninja /usr/bin/ninja
+COPY --from=deps-stage /usr/bin/pkg-config /usr/bin/pkg-config
+COPY --from=deps-stage /usr/bin/clang-14 /usr/bin/clang-14
+RUN ln -sf clang-14 /usr/bin/clang && ln -sf clang-14 /usr/bin/clang++
+
+# Copy libraries from debian stage (specific subdirectories to avoid overwriting Wolfi's core libs)
+COPY --from=deps-stage /usr/lib/x86_64-linux-gnu /usr/lib/x86_64-linux-gnu
+COPY --from=deps-stage /usr/lib/llvm-14 /usr/lib/llvm-14
+COPY --from=deps-stage /usr/lib/cmake /usr/lib/cmake
+COPY --from=deps-stage /usr/lib/gcc /usr/lib/gcc
+COPY --from=deps-stage /usr/include /usr/include
+COPY --from=deps-stage /usr/share/cmake-3.25 /usr/share/cmake-3.25
+COPY --from=deps-stage /usr/share/pkgconfig /usr/share/pkgconfig
+COPY --from=deps-stage /lib/x86_64-linux-gnu /lib/x86_64-linux-gnu
+
+# Remove Debian's glibc/ld files that conflict with Wolfi's newer glibc,
+# then register the Debian library paths and rebuild the linker cache
+RUN rm -f /usr/lib/x86_64-linux-gnu/libc.so* /usr/lib/x86_64-linux-gnu/libm.so* \
+         /usr/lib/x86_64-linux-gnu/libpthread* /usr/lib/x86_64-linux-gnu/libdl.so* \
+         /usr/lib/x86_64-linux-gnu/librt.so* /usr/lib/x86_64-linux-gnu/libresolv* \
+         /usr/lib/x86_64-linux-gnu/libmvec* /usr/lib/x86_64-linux-gnu/libnss_* \
+         /usr/lib/x86_64-linux-gnu/ld-linux* /usr/lib/x86_64-linux-gnu/crt*.o \
+         /usr/lib/x86_64-linux-gnu/libpcre2-8.so* \
+         /lib/x86_64-linux-gnu/libc.so* /lib/x86_64-linux-gnu/libc-* \
+         /lib/x86_64-linux-gnu/libm.so* /lib/x86_64-linux-gnu/libm-* \
+         /lib/x86_64-linux-gnu/libpthread* /lib/x86_64-linux-gnu/libdl.so* \
+         /lib/x86_64-linux-gnu/librt.so* /lib/x86_64-linux-gnu/libresolv* \
+         /lib/x86_64-linux-gnu/libmvec* /lib/x86_64-linux-gnu/libnss_* \
+         /lib/x86_64-linux-gnu/ld-linux* \
+         /lib/x86_64-linux-gnu/libpcre2-8.so* && \
+    echo "/usr/lib/x86_64-linux-gnu" > /etc/ld.so.conf.d/debian-x86_64.conf && \
+    echo "/lib/x86_64-linux-gnu" >> /etc/ld.so.conf.d/debian-x86_64.conf && \
+    ldconfig
+
+# Fix ownership before switching to flutter user
+RUN chown -R 65532:65532 /opt/flutter
+
+USER 65532
+
+# Configure Flutter for Linux desktop only
 RUN flutter config --enable-linux-desktop \
     --no-enable-web \
     --no-enable-android \
@@ -52,10 +101,4 @@ RUN flutter precache --linux \
 
 RUN flutter doctor -v
 
-# Create non-root user for CI builds
-RUN groupadd -r flutter && useradd -r -g flutter -m -d /home/flutter flutter && \
-    chown -R flutter:flutter "${FLUTTER_HOME}" /home/flutter
-
 WORKDIR /app
-RUN chown flutter:flutter /app
-USER flutter