fix dataplane and udp server builds on arm64 (#261)

.github/workflows/build.yaml

@@ -51,3 +51,36 @@ jobs:
     - name: Run Tests
       run: |
         make test
+  docker-build:
+    name: docker-build
+    runs-on: ubuntu-22.04
+    steps:
+      - name: Checkout
+        uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332 # v4.1.7
+      - uses: dorny/paths-filter@v3
+        id: filter
+        with:
+          filters: |
+            dataplane:
+              - 'dataplane/**'
+            containerfile:
+              - 'build/Containerfile.dataplane'
+      - name: Setup QEMU
+        if: steps.filter.outputs.dataplane || steps.filter.outputs.containerfile
+        uses: docker/setup-qemu-action@49b3bc8e6bdd4a60e6116a5414239cba5943d3cf # v3.2.0
+      - name: Setup Docker Buildx
+        if: steps.filter.outputs.dataplane || steps.filter.outputs.containerfile
+        id: buildx
+        uses: docker/setup-buildx-action@988b5a0280414f521da01fcc63a27aeeb4b104db # v3.6.1
+        with:
+          buildkitd-flags: "--debug"
+      - name: Build multi-arch container image
+        if: steps.filter.outputs.dataplane || steps.filter.outputs.containerfile
+        uses: docker/build-push-action@5cd11c3a4ced054e52742c5fd54dca954e0edd85 # v6.7.0
+        with:
+          push: false
+          builder: ${{ steps.buildx.outputs.name }}
+          context: .
+          platforms: linux/amd64,linux/arm64
+          file: build/Containerfile.dataplane
+          tags: kong/blixt-dataplane:${{ github.head_ref }}-${{ github.sha }}

build/Containerfile.dataplane

@@ -1,14 +1,21 @@
-FROM rust:1.75-slim-bookworm AS builder
+FROM rust:1.79-slim-bookworm as builder
 
 ARG TARGETARCH
+ARG LLVM_VERSION=19
 
 RUN apt-get update
 RUN apt-get install --yes \
     build-essential \
     protobuf-compiler \
     pkg-config \
-    llvm-16 \
-    musl-tools
+    musl-tools \
+    clang \
+    wget
+
+RUN apt install --yes lsb-release software-properties-common gnupg
+RUN wget -O /tmp/llvm.sh https://apt.llvm.org/llvm.sh
+RUN chmod +x /tmp/llvm.sh
+RUN /bin/sh -c "/tmp/llvm.sh ${LLVM_VERSION} all"
 
 RUN rustup default stable
 RUN rustup install nightly
@@ -35,7 +42,12 @@ COPY .cargo .cargo
 
 # We need to tell bpf-linker where it can find LLVM's shared library file.
 # Ref: https://github.com/aya-rs/rustc-llvm-proxy/blob/cbcb3c6/src/lib.rs#L48
-ENV LD_LIBRARY_PATH="/usr/lib/llvm-16/lib"
+ENV LD_LIBRARY_PATH="/usr/lib/llvm-$LLVM_VERSION/lib"
+ENV CC_aarch64_unknown_linux_musl="/usr/lib/llvm-$LLVM_VERSION/bin/clang"
+ENV AR_aarch64_unknown_linux_musl="/usr/lib/llvm-$LLVM_VERSION/bin/llvm-ar"
+ENV CC_x86_64_unknown_linux_musl="/usr/lib/llvm-$LLVM_VERSION/bin/clang"
+ENV AR_x86_64_unknown_linux_musl="/usr/lib/llvm-$LLVM_VERSION/bin/llvm-ar"
+ENV CARGO_TARGET_AARCH64_UNKNOWN_LINUX_MUSL_RUSTFLAGS="-Clink-self-contained=yes -Clinker=rust-lld"
 
 RUN --mount=type=cache,target=/workspace/target/ \
     --mount=type=cache,target=/root/.cargo/registry \

build/Containerfile.udp_server

@@ -1,8 +1,9 @@
 FROM rust AS builder
 
+ARG TARGETARCH
+
 RUN apt-get update && \
-    apt-get install musl-tools -yq && \
-    rustup target add x86_64-unknown-linux-musl
+    apt-get install musl-tools -yq
 
 WORKDIR /workspace
 
@@ -13,15 +14,24 @@ COPY tools/udp-test-server/Cargo.lock tools/udp-test-server/Cargo.lock
 COPY tools/udp-test-server/src/main.rs tools/udp-test-server/src/main.rs
 COPY xtask xtask
 
+# Docker uses the amd64/arm64 convention while Rust uses the x86_64/aarch64 convention.
+# Since Dockerfile doesn't support conditional variables (sigh), write the arch in Rust's
+# convention to a file for later usage.
+RUN if [ "$TARGETARCH" = "amd64" ]; \
+    then echo "x86_64" >> arch; \
+    else echo "aarch64" >> arch; \
+    fi
+RUN rustup target add $(eval cat arch)-unknown-linux-musl
+
 RUN --mount=type=cache,target=/workspace/target/ \
     --mount=type=cache,target=/usr/local/cargo/registry/ \
     RUSTFLAGS=-Ctarget-feature=+crt-static cargo build \
     --package=udp-test-server \
     --release \
-    --target=x86_64-unknown-linux-musl
+    --target=$(eval cat arch)-unknown-linux-musl
 
 RUN --mount=type=cache,target=/workspace/target/ \
-    cp /workspace/target/x86_64-unknown-linux-musl/release/udp-test-server /workspace/udp-test-server
+    cp /workspace/target/$(eval cat arch)-unknown-linux-musl/release/udp-test-server /workspace/udp-test-server
 
 FROM alpine
 

dataplane/loader/src/main.rs

@@ -35,7 +35,7 @@ async fn main() -> Result<(), anyhow::Error> {
         "../../target/bpfel-unknown-none/debug/loader"
     ))?;
     #[cfg(not(debug_assertions))]
-    let mut bpf = Ebpf::load(include_bytes_aligned!(
+    let mut bpf_program = Ebpf::load(include_bytes_aligned!(
         "../../target/bpfel-unknown-none/release/loader"
     ))?;
     if let Err(e) = EbpfLogger::init(&mut bpf_program) {