Fixes multiplatform builds (#6)

Signed-off-by: Takeshi Yoneda <[email protected]>

Author: mathetake

.github/workflows/commit.yaml

@@ -112,9 +112,8 @@ jobs:
         platform:
           - os: ubuntu-22.04
             arch: amd64
-          # TODO: fix
-          # - os: ubuntu-22.04-arm
-          #   arch: arm64
+          - os: ubuntu-22.04-arm
+            arch: arm64
 
     steps:
       - name: Checkout

Dockerfile

@@ -1,21 +1,28 @@
-FROM --platform=$BUILDPLATFORM rust:1.84 AS rust_builder
-
-# We need libclang to do the bindgen.
-RUN apt update && apt install -y clang
+FROM --platform=$BUILDPLATFORM rust:1.84 AS rust_fetcher
 
 WORKDIR /app
 
-# Cache dependencies by copying only the Cargo files and fetching them.
+# Cache dependencies by copying only the Cargo files and fetching them on the build platform.
 COPY ./rust/Cargo.toml ./rust/Cargo.lock ./
 RUN mkdir src && echo "" > src/lib.rs
 RUN cargo fetch
 RUN rm -rf src
 
+FROM rust:1.84 AS rust_builder
+
+# We need libclang to do the bindgen.
+RUN apt update && apt install -y clang
+
+# Copy the dependencies from the previous stage.
+WORKDIR /app
+COPY --from=rust_fetcher /usr/local/cargo/git /usr/local/cargo/git
+COPY --from=rust_fetcher /usr/local/cargo/registry /usr/local/cargo/registry
+
 # Then, copy the entire source code and build.
 COPY ./rust .
 RUN cargo build
 
 # Finally, copy the built library to the final image.
-FROM --platform=$BUILDPLATFORM envoyproxy/envoy-dev:80c1ac2143a7a73932c9dff814d38fd6867fe691 AS envoy
+FROM envoyproxy/envoy-dev:80c1ac2143a7a73932c9dff814d38fd6867fe691 AS envoy
 ENV ENVOY_DYNAMIC_MODULES_SEARCH_PATH=/usr/local/lib
 COPY --from=rust_builder /app/target/debug/librust_module.so /usr/local/lib/librust_module.so