Optimize Docker build: Build assets outside ARM emulation

- Add multi-stage build with separate composer-deps and assets stages
- Assets are built once on native platform (node:22-bookworm-slim)
- Pre-built assets copied into final images for all platforms
- Remove Node.js/Yarn installation from final images (smaller size)
- Use --ignore-platform-reqs for composer in assets stage
- Applies to both Dockerfile and Dockerfile-frankenphp

Co-authored-by: jbtronics <5410681+jbtronics@users.noreply.github.com>

Dockerfile-frankenphp

@@ -1,3 +1,34 @@
+# ---
+# Build assets stage - runs on native platform (not emulated)
+# This stage builds the frontend assets (JavaScript, CSS) using Node.js and Yarn
+FROM composer:latest AS composer-deps
+
+WORKDIR /build
+
+# Copy composer files and install PHP dependencies (needed for Symfony UX assets)
+COPY composer.json composer.lock symfony.lock ./
+RUN composer install --no-dev --no-scripts --no-autoloader --prefer-dist --ignore-platform-reqs
+
+# ---
+
+FROM node:22-bookworm-slim AS assets
+
+WORKDIR /build
+
+# Copy vendor directory from composer stage (needed for Symfony UX packages)
+COPY --from=composer-deps /build/vendor ./vendor
+
+# Copy package files
+COPY package.json yarn.lock webpack.config.js ./
+COPY assets ./assets
+
+# Install dependencies and build assets
+RUN yarn install --network-timeout 600000 && \
+    yarn build && \
+    yarn cache clean
+
+# ---
+
 FROM dunglas/frankenphp:1-php8.4 AS frankenphp_upstream
 
 RUN apt-get update && apt-get -y install \
@@ -13,33 +44,6 @@ RUN apt-get update && apt-get -y install \
       zip \
     && apt-get -y autoremove && apt-get clean autoclean && rm -rf /var/lib/apt/lists/*;
 
-RUN set -eux; \
-    # Prepare keyrings directory
-    mkdir -p /etc/apt/keyrings; \
-    \
-    # Import Yarn GPG key
-    curl -fsSL https://dl.yarnpkg.com/debian/pubkey.gpg \
-      | tee /etc/apt/keyrings/yarn.gpg >/dev/null; \
-    chmod 644 /etc/apt/keyrings/yarn.gpg; \
-    \
-    # Add Yarn repo with signed-by
-    echo "deb [signed-by=/etc/apt/keyrings/yarn.gpg] https://dl.yarnpkg.com/debian stable main" \
-      | tee /etc/apt/sources.list.d/yarn.list; \
-    \
-    # Run NodeSource setup script (unchanged)
-    curl -sL https://deb.nodesource.com/setup_22.x | bash -; \
-    \
-    # Install Node.js + Yarn
-    apt-get update; \
-    apt-get install -y --no-install-recommends \
-      nodejs \
-      yarn; \
-    \
-    # Cleanup
-    apt-get -y autoremove; \
-    apt-get clean autoclean; \
-    rm -rf /var/lib/apt/lists/*
-
 
 # Install PHP
 RUN set -eux; \
@@ -90,10 +94,8 @@ RUN set -eux; \
 	composer run-script --no-dev post-install-cmd; \
 	chmod +x bin/console; sync;
 
-RUN yarn install --network-timeout 600000 && \
-    yarn build && \
-    yarn cache clean && \
-    rm -rf node_modules/
+# Copy pre-built assets from the assets stage
+COPY --from=assets /build/public/build ./public/build
 
 # Use docker env to output logs to stdout
 ENV APP_ENV=docker