feat: use rustembedded/cross images and use static relocation model to fix cross-compile

.gitlab-ci.yml

@@ -21,33 +21,46 @@ variables:
     - if: '$CI_COMMIT_BRANCH == "next"'
     - if: "$CI_COMMIT_TAG"
   interruptible: true
-  image: "rust:1.56"
+  image: "rust:1.58"
   tags: ["docker"]
+  services: ["docker:dind"]
   variables:
+    DOCKER_HOST: tcp://docker:2375/
+    DOCKER_TLS_CERTDIR: ""
+    DOCKER_DRIVER: overlay2
+    SHARED_PATH: $CI_PROJECT_DIR/shared/
     CARGO_PROFILE_RELEASE_LTO: "true"
     CARGO_PROFILE_RELEASE_CODEGEN_UNITS: "1"
     CARGO_INCREMENTAL: "false" # https://matklad.github.io/2021/09/04/fast-rust-builds.html#ci-workflow
   before_script:
     - 'echo "Building for target $TARGET"'
-    - "rustc --version && cargo --version && rustup show" # Print version info for debugging
-    - "rustup target add $TARGET"
+    - "rustup show && rustc --version && cargo --version" # Print version info for debugging
     # If provided, bring in caching through sccache, which uses an external S3 endpoint to store compilation results:
     - if [ -n "${SCCACHE_BIN_URL}" ]; then curl $SCCACHE_BIN_URL --output /sccache && chmod +x /sccache && export RUSTC_WRAPPER=/sccache; fi
-    # Make sure that cc-rs links the correct libraries statically when cross-compiling
-    # See https://github.com/alexcrichton/cc-rs#external-configuration-via-environment-variables for more information
-    - 'export CARGO_BUILD_RUSTFLAGS="-L$TARGET_HOME/lib -latomic" CXXSTDLIB="static=stdc++"'
-    # Make sure that rust-bindgen uses the correct include path when cross-compiling
-    # See https://github.com/rust-lang/rust-bindgen#environment-variables for more information
-    - 'export BINDGEN_EXTRA_CLANG_ARGS="-I$TARGET_C_INCLUDE_PATH"'
   script:
-    - time cargo build --target $TARGET --release
+    # install cross-compiling prerequisites
+    - 'apt-get update && apt-get install -y docker.io && docker version' # install docker
+    - 'cargo install cross && cross --version' # install cross
+    # fix cargo and rustup mounts from this container (https://gitlab.com/gitlab-org/gitlab-foss/-/issues/41227)
+    - 'mkdir -p $SHARED_PATH/cargo'
+    - 'cp -r $CARGO_HOME/bin $SHARED_PATH/cargo'
+    - 'cp -r $RUSTUP_HOME $SHARED_PATH'
+    - 'export CARGO_HOME=$SHARED_PATH/cargo RUSTUP_HOME=$SHARED_PATH/rustup'
+    # cross-compile conduit for target
+    - 'time ./cross/build.sh --locked --release'
     - 'cp "target/$TARGET/release/conduit" "conduit-$TARGET"'
+  cache:
+    # https://doc.rust-lang.org/cargo/guide/cargo-home.html#caching-the-cargo-home-in-ci
+    - key: 'cargo-cache-$TARGET'
+      paths:
+        - $SHARED_PATH/cargo/registry/index
+        - $SHARED_PATH/cargo/registry/cache
+        - $SHARED_PATH/cargo/git/db
   artifacts:
     expire_in: never
 
 build:release:cargo:x86_64-unknown-linux-musl-with-debug:
   extends: .build-cargo-shared-settings
-  image: messense/rust-musl-cross:x86_64-musl
   variables:
     CARGO_PROFILE_RELEASE_DEBUG: 2 # Enable debug info for flamegraph profiling
     TARGET: "x86_64-unknown-linux-musl"
@@ -61,7 +74,6 @@ build:release:cargo:x86_64-unknown-linux-musl-with-debug:
 
 build:release:cargo:x86_64-unknown-linux-musl:
   extends: .build-cargo-shared-settings
-  image: messense/rust-musl-cross:x86_64-musl
   variables:
     TARGET: "x86_64-unknown-linux-musl"
   artifacts:
@@ -72,7 +84,6 @@ build:release:cargo:x86_64-unknown-linux-musl:
 
 build:release:cargo:arm-unknown-linux-musleabihf:
   extends: .build-cargo-shared-settings
-  image: messense/rust-musl-cross:arm-musleabihf
   variables:
     TARGET: "arm-unknown-linux-musleabihf"
   artifacts:
@@ -83,7 +94,6 @@ build:release:cargo:arm-unknown-linux-musleabihf:
 
 build:release:cargo:armv7-unknown-linux-musleabihf:
   extends: .build-cargo-shared-settings
-  image: messense/rust-musl-cross:armv7-musleabihf
   variables:
     TARGET: "armv7-unknown-linux-musleabihf"
   artifacts:
@@ -94,7 +104,6 @@ build:release:cargo:armv7-unknown-linux-musleabihf:
 
 build:release:cargo:aarch64-unknown-linux-musl:
   extends: .build-cargo-shared-settings
-  image: messense/rust-musl-cross:aarch64-musl
   variables:
     TARGET: "aarch64-unknown-linux-musl"
   artifacts:

CROSS_COMPILE.md

@@ -1,11 +0,0 @@
-Install docker:
-
-```
-$ sudo apt install docker
-$ sudo usermod -aG docker $USER
-$ exec sudo su -l $USER
-$ sudo systemctl start docker
-$ cargo install cross
-$ cross build --release --target armv7-unknown-linux-musleabihf
-```
-The cross-compiled binary is at target/armv7-unknown-linux-musleabihf/release/conduit

Cross.toml

@@ -0,0 +1,11 @@
+[target.aarch64-unknown-linux-musl]
+image = "rust-cross:aarch64-unknown-linux-musl"
+
+[target.arm-unknown-linux-musleabihf]
+image = "rust-cross:arm-unknown-linux-musleabihf"
+
+[target.armv7-unknown-linux-musleabihf]
+image = "rust-cross:armv7-unknown-linux-musleabihf"
+
+[target.x86_64-unknown-linux-musl]
+image = "rust-cross:x86_64-unknown-linux-musl"

DEPLOY.md

@@ -37,7 +37,7 @@ $ cargo build --release
 
 Note that this currently requires Rust 1.50.
 
-If you want to cross compile Conduit to another architecture, read the [Cross-Compile Guide](CROSS_COMPILE.md).
+If you want to cross compile Conduit to another architecture, read the [Cross-Compile Guide](cross/README.md).
 
 ## Adding a Conduit user
 

cross/README.md

@@ -0,0 +1,37 @@
+## Cross compilation
+
+The `cross` folder contains a set of convenience scripts (`build.sh` and `test.sh`) for cross-compiling Conduit.
+
+Currently supported targets are
+
+- aarch64-unknown-linux-musl
+- arm-unknown-linux-musleabihf
+- armv7-unknown-linux-musleabihf
+- x86\_64-unknown-linux-musl
+
+### Install prerequisites
+#### Docker
+[Installation guide](https://docs.docker.com/get-docker/).
+```sh
+$ sudo apt install docker
+$ sudo systemctl start docker
+$ sudo usermod -aG docker $USER
+$ newgrp docker
+```
+
+#### Cross
+[Installation guide](https://github.com/rust-embedded/cross/#installation).
+```sh
+$ cargo install cross
+```
+
+### Buiding Conduit
+```sh
+$ TARGET=armv7-unknown-linux-musleabihf ./cross/build.sh --release
+```
+The cross-compiled binary is at `target/armv7-unknown-linux-musleabihf/release/conduit`
+
+### Testing Conduit
+```sh
+$ TARGET=armv7-unknown-linux-musleabihf ./cross/test.sh --release
+```

cross/build.sh

@@ -0,0 +1,31 @@
+#!/bin/bash
+set -ex
+
+# build custom container with libclang and static compilation
+tag="rust-cross:${TARGET:?}"
+docker build --tag="$tag" - << EOF
+FROM rustembedded/cross:$TARGET
+
+# Install libclang for generating bindings with rust-bindgen
+# The architecture is not relevant here since it's not used for compilation
+RUN apt-get update && \
+    apt-get install --assume-yes libclang-dev
+
+# Set the target prefix
+ENV TARGET_PREFIX="/usr/local/$(echo "${TARGET:?}" | sed -e 's/armv7/arm/' -e 's/-unknown//')"
+
+# Make sure that cc-rs links libc/libstdc++ statically when cross-compiling
+# See https://github.com/alexcrichton/cc-rs#external-configuration-via-environment-variables for more information
+ENV RUSTFLAGS="-L\$TARGET_PREFIX/lib" CXXSTDLIB="static=stdc++"
+# Forcefully linking against libatomic, libc and libgcc is required for arm32, otherwise symbols are missing
+$([[ $TARGET =~ arm ]] && echo 'ENV RUSTFLAGS="$RUSTFLAGS -Clink-arg=-lgcc -Clink-arg=-latomic -lstatic=c"')
+# Strip symbols while compiling in release mode
+$([[ $@ =~ -r ]] && echo 'ENV RUSTFLAGS="$RUSTFLAGS -Clink-arg=-s"')
+
+# Make sure that rust-bindgen uses the correct include path when cross-compiling
+# See https://github.com/rust-lang/rust-bindgen#environment-variables for more information
+ENV BINDGEN_EXTRA_CLANG_ARGS="-I\$TARGET_PREFIX/include"
+EOF
+
+# build conduit for a specific target
+cross build --target="$TARGET" $@

cross/test.sh

@@ -0,0 +1,8 @@
+#!/usr/bin/env sh
+set -ex
+
+# Build conduit for a specific target
+cross/build.sh $@
+
+# Test conduit for a specific target
+cross test --target="$TARGET" $@