golang-cross

Docker container to turn CGO cross-compilation pain into a pleasure on variety of platforms including usage of custom sysroots. Although cross-compilation without CGO works well too, it is probably better to call goreleaser directly as it saves time on downloading quite big Docker image, especially on CI environment

Tip! Should you wish to see working examples instead of reading

Credits

This project is rather cookbook. Actual work to create cross-compile environment is done by osxcross and golang-cross

Docker

Docker image

To run build with CGO each entry requires some environment variables

Env variable	value	required	Notes
CGO_ENABLED	1	Yes	instead of specifying it in each build it can be set globally during docker run -e CGO_ENABLED=1
CC	see targets	Optional
CXX	see targets	Optional
PKG_CONFIG_SYSROOT_DIR		Required if sysroot is present
PKG_CONFIG_PATH		Optional	List of directories containing pkg-config files

PKG_CONFIG_SYSROOT_DIR Modifies -I and -L to use the directories located in target sys root. This option is required when cross-compiling packages that use pkg-config to determine CFLAGS and LDFLAGS. -I and -L are modified to point to the new system root. This means that a -I/usr/include/libfoo will become -I/var/target/usr/include/libfoo with a PKG_CONFIG_SYSROOT_DIR equal to /var/target (same rule apply to -L)

PKG_CONFIG_PATH - A colon-separated list of directories to search for .pc files. The default directory will always be searched after searching the path; the default is libdir/pkgconfig:datadir/pkgconfig where libdir is the libdir for pkg-config and datadir is the datadir for pkg-config when it was installed.

Supported toolchains/platforms

Platform	Arch	CC	CXX	Verified
Darwin	amd64	o64-clang	o64-clang++	✅
Linux	amd64	gcc	g++	✅
Linux	arm64	aarch64-linux-gnu-gcc	aarch64-linux-gnu-g++	✅
Linux	armhf (GOARM=5)	arm-linux-gnueabihf-gcc	arm-linux-gnueabihf-g++	Verification required
Linux	armhf (GOARM=6)	arm-linux-gnueabihf-gcc	arm-linux-gnueabihf-g++	Verification required
Linux	armhf (GOARM=7)	arm-linux-gnueabihf-gcc	arm-linux-gnueabihf-g++	✅
Window	amd64	x86_64-w64-mingw32-gcc	x86_64-w64-mingw32-g++	Verification required

Docker

Environment variables

• GPG_KEY - defaults to /secrets/key.gpg. ignored if file not found
• DOCKER_USERNAME
• DOCKER_PASSWORD
• DOCKER_HOST - defaults to hub.docker.io. ignored if DOCKER_USERNAME and DOCKER_PASSWORD are empty or DOCKER_CREDS_FILE is present
• DOCKER_CREDS_FILE - path to file with docker login credentials in colon separated format user:password:<registry>. useful when push to multiple docker registries required

  user1:password1:hub.docker.io
  user2:password2:registry.gitlab.com
  

• DOCKER_FAIL_ON_LOGIN_ERROR - fail on docker login error
• GITHUB_TOKEN - github auth token to deploy release

Sysroot

Most reasonable way to make a sysroot seem to be rsync and this example is using it. This script can help you with creating sysroot. Lets consider creating sysroot for Raspberry Pi 4 running Debian Buster.

• install all required dev packages. for this example we will install libftdi1-dev, libusb-1.0-0-dev and opencv4

  ./sysroot-rsync.sh pi@<ipaddress> <local destination>

sshfs

sshfs is a good way to test sysroot before running rsync with one minor issue. Some packages are creating absolute links and the become unusable or pointing to wrong files when mounted For example /usr/lib/x86_x64-gnu-linux/libpthread.so on RPI4 running Debian Buster is symlink to /lib/x86_x64-gnu-linux/libpthread.so

Contributing

Any contribution helping to make this project is welcome

Examples

• Example described in this tutorial

Projects using

• Akash