Add frontend to Dockerfile and use cross-platform build

Dockerfile

@@ -1,54 +1,62 @@
 # Dockerfile References: https://docs.docker.com/engine/reference/builder/
 # This dockerfile uses a multi-stage build system to reduce the image footprint.
 
-######-
-# Start from the latest golang base image as builder image (only used to compile the code)
-######-
-FROM golang:1.21 as builder
-
-ARG BUILD_IDENTIFIER
-ENV ENV_BUILD_IDENTIFIER=$BUILD_IDENTIFIER
-
-ARG BUILD_VERSION
-ENV ENV_BUILD_VERSION=$BUILD_VERSION
-
-# populated by BuildKit
-ARG TARGETPLATFORM
-ENV ENV_TARGETPLATFORM=$TARGETPLATFORM
-
-RUN mkdir /build
-
-# Copy the source from the current directory to the Working Directory inside the container
-ADD . /build/
-
-# Set the Current Working Directory inside the container
+######
+# Build frontend
+######
+FROM --platform=${BUILDPLATFORM} node:lts-alpine as frontend
+# Set the working directory
 WORKDIR /build
+# Download dependencies
+COPY frontend/package.json frontend/package-lock.json ./
+RUN npm ci
+# Set dist output directory
+ENV DIST_OUT_DIR="dist"
+# Copy the sources to the working directory
+COPY frontend .
+# Build the frontend
+RUN npm run build
 
+######
+# Build backend
+######
+FROM --platform=${BUILDPLATFORM} golang:1.21 as builder
+# Set the working directory
+WORKDIR /build
+# Download dependencies
+COPY go.mod go.sum ./
+RUN go mod download
+# Copy the sources to the working directory
+COPY . .
+# Copy the frontend build result
+COPY --from=frontend /build/dist/ ./internal/app/api/core/frontend-dist/
+# Set the build version and identifier from arguments
+ARG BUILD_IDENTIFIER BUILD_VERSION
+ENV ENV_BUILD_IDENTIFIER=${BUILD_IDENTIFIER}
+ENV ENV_BUILD_VERSION=${BUILD_VERSION}
+
+# Split to cross-platform build
+ARG TARGETARCH
+ENV GOARCH=${TARGETARCH}
 # Build the Go app
-RUN echo "Building version '$ENV_BUILD_IDENTIFIER-$ENV_BUILD_VERSION' for platform $ENV_TARGETPLATFORM"; make build
+RUN echo "Building version '$ENV_BUILD_IDENTIFIER-$ENV_BUILD_VERSION' for architecture $TARGETARCH"
+RUN make build
 
-######-
-# Here starts the main image
-######-
+######
+# Final image
+######
 FROM alpine:3.19
-
 # Install OS-level dependencies
 RUN apk add --no-cache bash openresolv
-
 # Setup timezone
 ENV TZ=Europe/Vienna
-
 # Copy binaries
 COPY --from=builder /build/dist/wg-portal /app/wg-portal
-
 # Set the Current Working Directory inside the container
 WORKDIR /app
-
 # by default, the web-portal is reachable on port 8888
 EXPOSE 8888/tcp
-
 # the database and config file can be mounted from the host
 VOLUME [ "/app/data", "/app/config" ]
-
 # Command to run the executable
 ENTRYPOINT [ "/app/wg-portal" ]