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Add UPX Binary Compression to Reduce Release Sizes #85

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feat(build): add UPX compression to reduce binary size
remmody Mar 3, 2026
23e5a1d
Merge branch 'main' of https://github.com/remmody/b4
remmody Mar 3, 2026
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35 changes: 35 additions & 0 deletions .github/workflows/release.yml
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Original file line number Diff line number Diff line change
Expand Up @@ -104,10 +104,45 @@ jobs:
name: ui-build
path: src/http/ui/dist

- name: Install UPX
run: |
sudo apt-get update
sudo apt-get install -y upx-ucl

- name: Build using Makefile
run: |
make linux-${{ matrix.arch }} VERSION="$VERSION"

- name: Compress with UPX
run: |
ARCH="${{ matrix.arch }}"
BINARY_PATH="out/linux-${ARCH}/${{ env.BINARY_NAME }}"

if [ -f "$BINARY_PATH" ]; then
echo "Compressing $BINARY_PATH with UPX..."
upx --ultra-brute --lzma "$BINARY_PATH" -o "${BINARY_PATH}.upx"

Comment on lines +123 to +124
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Copilot AI Mar 4, 2026

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--ultra-brute --lzma can make the release workflow substantially slower across the full arch matrix. Unless maximum compression is required, consider a faster default (e.g., --best) and/or make the compression level configurable (workflow input/env) so you can trade off size vs. build time.

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# Test compressed binary
if upx -t "${BINARY_PATH}.upx"; then
echo "UPX compression successful, replacing original binary"
mv "${BINARY_PATH}.upx" "$BINARY_PATH"
else
echo "UPX test failed, keeping original binary"
Comment on lines +123 to +130
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This step intends to keep the original binary if UPX fails, but with GitHub Actions’ default bash -e behavior the command upx --ultra-brute --lzma ... will fail the step immediately on any non-zero exit code (e.g., unsupported arch/format), and the fallback logic below won’t run. Wrap the compression command in an if upx ...; then ... else ... block (or otherwise handle the exit status) so the fallback actually works.

Suggested change
upx --ultra-brute --lzma "$BINARY_PATH" -o "${BINARY_PATH}.upx"
# Test compressed binary
if upx -t "${BINARY_PATH}.upx"; then
echo "UPX compression successful, replacing original binary"
mv "${BINARY_PATH}.upx" "$BINARY_PATH"
else
echo "UPX test failed, keeping original binary"
if upx --ultra-brute --lzma "$BINARY_PATH" -o "${BINARY_PATH}.upx"; then
# Test compressed binary
if upx -t "${BINARY_PATH}.upx"; then
echo "UPX compression successful, replacing original binary"
mv "${BINARY_PATH}.upx" "$BINARY_PATH"
else
echo "UPX test failed, keeping original binary"
rm -f "${BINARY_PATH}.upx"
fi
else
echo "UPX compression failed (possibly unsupported arch/format), keeping original binary"

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rm -f "${BINARY_PATH}.upx"
fi
else
echo "Binary not found at $BINARY_PATH"
exit 1
fi

- name: Repackage with compressed binary
run: |
ARCH="${{ matrix.arch }}"
cd out/linux-${ARCH}
tar -czf "../assets/${{ env.BINARY_NAME }}-linux-${ARCH}.tar.gz" "${{ env.BINARY_NAME }}"
cd ../assets
sha256sum "${{ env.BINARY_NAME }}-linux-${ARCH}.tar.gz" > "${{ env.BINARY_NAME }}-linux-${ARCH}.tar.gz.sha256"

- name: Upload artifacts
uses: actions/upload-artifact@v4
with:
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21 changes: 13 additions & 8 deletions Dockerfile
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Expand Up @@ -33,21 +33,26 @@ RUN COMMIT=$(echo "docker" ) && \
GOARM=${TARGETVARIANT#v} \
CGO_ENABLED=0 GOOS=linux GOARCH=${TARGETARCH} go -C src build \
-trimpath \
-buildvcs=false \
-ldflags "-s -w -X main.Version=${VERSION} -X main.Commit=${COMMIT} -X main.Date=${DATE}" \
-o /b4

# Stage 2.5: UPX compression
FROM --platform=$TARGETPLATFORM alpine:3.23.3 AS upx-compressor
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The UPX stage is pinned to --platform=$TARGETPLATFORM, which means during cross-platform builds (e.g., building linux/arm64 on an amd64 runner) the upx binary itself will run under QEMU emulation. That typically slows builds significantly and can fail if emulation isn’t available. Consider running the compressor stage on $BUILDPLATFORM (tooling runs native) while still compressing the target-arch /b4 output.

Suggested change
FROM --platform=$TARGETPLATFORM alpine:3.23.3 AS upx-compressor
FROM --platform=$BUILDPLATFORM alpine:3.23.3 AS upx-compressor

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RUN apk add --no-cache upx

COPY --from=go-builder /b4 /b4
RUN upx --ultra-brute --lzma /b4 -o /b4.upx && upx -t /b4.upx
Comment on lines +43 to +46
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upx --ultra-brute --lzma is extremely CPU-intensive and can add a large amount of time to Docker builds (especially under QEMU when cross-building). Consider switching to a less expensive preset (e.g., --best) or making the compression level configurable via a build arg so release builds can opt into ultra-brute when needed.

Suggested change
RUN apk add --no-cache upx
COPY --from=go-builder /b4 /b4
RUN upx --ultra-brute --lzma /b4 -o /b4.upx && upx -t /b4.upx
ARG UPX_FLAGS="--best"
RUN apk add --no-cache upx
COPY --from=go-builder /b4 /b4
RUN upx ${UPX_FLAGS} /b4 -o /b4.upx && upx -t /b4.upx

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# Stage 3: Runtime image
FROM alpine:3.23.3

RUN apk add --no-cache \
iptables \
ip6tables \
nftables \
kmod \
iproute2 \
tzdata

COPY --from=go-builder /b4 /usr/local/bin/b4
iptables ip6tables nftables kmod iproute2 tzdata \
&& rm -rf /var/cache/apk/*

COPY --from=upx-compressor /b4.upx /usr/local/bin/b4

VOLUME /etc/b4
EXPOSE 7000
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