fix: pass RUSTC_WRAPPER to the cross container and enforce static builds

.gitlab-ci.yml

@@ -35,8 +35,6 @@ variables:
   before_script:
     - 'echo "Building for target $TARGET"'
     - "rustup show && rustc --version && cargo --version" # Print version info for debugging
-    # If provided, bring in caching through sccache, which uses an external S3 endpoint to store compilation results:
-    - if [ -n "${SCCACHE_BIN_URL}" ]; then curl $SCCACHE_BIN_URL --output /sccache && chmod +x /sccache && export RUSTC_WRAPPER=/sccache; fi
     # install cross-compiling prerequisites
     - 'apt-get update && apt-get install -y docker.io && docker version' # install docker
     - 'cargo install cross && cross --version' # install cross
@@ -45,10 +43,14 @@ variables:
     - 'cp -r $CARGO_HOME/bin $SHARED_PATH/cargo'
     - 'cp -r $RUSTUP_HOME $SHARED_PATH'
     - 'export CARGO_HOME=$SHARED_PATH/cargo RUSTUP_HOME=$SHARED_PATH/rustup'
+    # If provided, bring in caching through sccache, which uses an external S3 endpoint to store compilation results:
+    - if [ -n "${SCCACHE_BIN_URL}" ]; then export RUSTC_WRAPPER=$SHARED_PATH/cargo/bin/sccache && curl $SCCACHE_BIN_URL --output $RUSTC_WRAPPER && chmod +x $RUSTC_WRAPPER; fi
   script:
     # cross-compile conduit for target
     - 'time ./cross/build.sh --locked --release'
     - 'mv "target/$TARGET/release/conduit" "conduit-$TARGET"'
+    # assert that the binary is statically linked
+    - 'file conduit-$TARGET | grep "static\(-pie\|ally\) linked"'
   cache:
     # https://doc.rust-lang.org/cargo/guide/cargo-home.html#caching-the-cargo-home-in-ci
     key: 'cargo-cache-$TARGET'
@@ -82,16 +84,6 @@ build:release:cargo:x86_64-unknown-linux-musl:
       - "conduit-x86_64-unknown-linux-musl"
     expose_as: "Conduit for x86_64-unknown-linux-musl"
 
-build:release:cargo:i686-unknown-linux-musl:
-  extends: .build-cargo-shared-settings
-  variables:
-    TARGET: "i686-unknown-linux-musl"
-  artifacts:
-    name: "conduit-i686-unknown-linux-musl"
-    paths:
-      - "conduit-i686-unknown-linux-musl"
-    expose_as: "Conduit for i686-unknown-linux-musl"
-
 build:release:cargo:arm-unknown-linux-musleabihf:
   extends: .build-cargo-shared-settings
   variables:
@@ -132,6 +124,8 @@ build:release:cargo:aarch64-unknown-linux-musl:
     # cross-compile conduit for target
     - 'time ./cross/build.sh --locked'
     - 'mv "target/$TARGET/debug/conduit" "conduit-debug-$TARGET"'
+    # assert that the binary is statically linked
+    - 'file conduit-debug-$TARGET | grep "static\(-pie\|ally\) linked"'
   artifacts:
     expire_in: 4 weeks
 

Cross.toml

@@ -7,8 +7,5 @@ image = "rust-cross:arm-unknown-linux-musleabihf"
 [target.armv7-unknown-linux-musleabihf]
 image = "rust-cross:armv7-unknown-linux-musleabihf"
 
-[target.i686-unknown-linux-musl]
-image = "rust-cross:i686-unknown-linux-musl"
-
 [target.x86_64-unknown-linux-musl]
 image = "rust-cross:x86_64-unknown-linux-musl"

cross/build.sh

@@ -17,13 +17,14 @@ ENV TARGET_PREFIX="/usr/local/$(echo "${TARGET:?}" | sed -e 's/armv7/arm/' -e 's
 # 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 and libgcc is required for arm32, otherwise symbols are missing
-$([[ $TARGET =~ arm ]] && echo 'ENV RUSTFLAGS="$RUSTFLAGS -Clink-arg=-lgcc -Clink-arg=-latomic"')
-# Forcefully linking against libc is required for 32-bit, otherwise symbols are missing
-$([[ $TARGET =~ arm|i686 ]] && echo 'ENV RUSTFLAGS="$RUSTFLAGS -lstatic=c"')
+# 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"')
 
+# Support a rustc wrapper like sccache when cross-compiling
+ENV RUSTC_WRAPPER="$RUSTC_WRAPPER"
+
 # 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"