Enable cross-compilation for cargo plugins

Dockerfile

@@ -1,8 +1,37 @@
 ARG RUST_VERSION=1.80.1
+FROM --platform=$BUILDPLATFORM rust:${RUST_VERSION}-alpine3.20 AS tools-host
+ARG BUILDPLATFORM
+ARG TARGETARCH
+
+ENV TARGETS="x86_64-unknown-linux-musl aarch64-unknown-linux-musl x86_64-unknown-linux-gnu aarch64-unknown-linux-gnu riscv64gc-unknown-linux-gnu"
+RUN rustup target add ${TARGETS}
+RUN apk add musl-dev linux-headers make clang mold
+
+FROM tools-host AS target-amd64
+ENV CARGO_BUILD_TARGET="x86_64-unknown-linux-musl"
+
+FROM tools-host AS target-arm64
+ENV CARGO_BUILD_TARGET="aarch64-unknown-linux-musl"
+
+FROM tools-host AS target-riscv64
+ENV CARGO_BUILD_TARGET="riscv64gc-unknown-linux-gnu"
+
+FROM target-$TARGETARCH AS tools
+RUN echo "Cargo target: $CARGO_BUILD_TARGET"
+
+ADD config.toml /usr/local/cargo/
+# CARGO_BUILD_TARGET is respected by cargo install and other cargo commands
+RUN cargo install --root /cargo-cross [email protected] [email protected]
+
+
 FROM rust:${RUST_VERSION}-alpine3.20
 ENV TARGETS="x86_64-unknown-linux-musl aarch64-unknown-linux-musl x86_64-unknown-linux-gnu aarch64-unknown-linux-gnu riscv64gc-unknown-linux-gnu"
 RUN rustup target add ${TARGETS}
 
 # needed for cargo-chef and cargo-sbom, as well as many other compilations
-RUN apk add musl-dev linux-headers make
-RUN cargo install [email protected] [email protected]
+RUN apk add musl-dev linux-headers make clang mold
+
+# copy the cargo plugins from the tools stage
+COPY --from=tools /cargo-cross /usr/local/cargo
+# we define target specific rustc flags for cross-compilation
+ADD config.toml /usr/local/cargo/

config.toml

@@ -0,0 +1,28 @@
+[target.aarch64-unknown-linux-musl]
+linker = "/usr/bin/clang"
+rustflags = [
+    "-C",
+    "link-arg=--ld-path=/usr/bin/mold",
+    "-C",
+    "link-arg=--target=aarch64-unknown-linux-musl",
+]
+
+[target.x86_64-unknown-linux-musl]
+linker = "/usr/bin/clang"
+rustflags = [
+    "-C",
+    "link-arg=--ld-path=/usr/bin/mold",
+    "-C",
+    "link-arg=--target=x86_64-unknown-linux-musl",
+]
+
+# FIXME: riscv64 is not yet available in rust:1.80.1-alpine3.20
+# but both clang and mold support it. Alos musl-dev is available in Alpine 3.20
+# [target.riscv64gc-unknown-linux-gnu]
+# linker = "/usr/bin/clang"
+# rustflags = [
+#     "-C",
+#     "link-arg=--ld-path=/usr/bin/mold",
+#     "-C",
+#     "link-arg=--target=riscv64-unknown-linux-musl",
+# ]