Cross Compiling With Go

A big difference between using compiled languages like C/C++ compared to scripting languages like Javascript or Python is that prior to execution, compiled languages require an explicit compilation step where the human readable code is translated to machine code for execution, the so-called “binary” of the code. Typically, a separate binary needs to be compiled for each target operating system and architecture. Compiling for your own machine is not a problem. The difficulty lies in creating binaries for machines that you don’t normally use, so you might not have an extra Mac lying around just to compile your program on for other Mac users. Compiling programs for an operating system or architecture other than the one you are working with is called cross-compiling. This would allow a Linux developer to create binaries for Windows and Mac computers, for example.

For most languages, this requires installing additional development tools and increases the complexity of the compilation workflow. I have found Go to be a pleasant exception to this, because cross-compilation is built into the standard Go tools. There is no need to learn any additional build-tools. All you need to learn about are some system variables that you need to set when compiling.

Go build tools know which system you are building for by checking the GOOS and GOARCH environment variables. If they are unset, the tools fall back to GOHOSTOS and GOHOSTARCH. In other words, to change the target OS/architecture for your build, all you have to do is set the GOOS and GOARCH variables during the build. So say you want to build a simple program hello.go for a Windows computer with the same architecture as your development machine. All you have to do is write

GOOS=windows go build hello.go

instead of just go build hello.go and you’re good to go. This would produce a hello.exe binary you could copy to a Windows machine to run.

To check what combinations of GOOS and GOARCH are valid, run go tool dist list. To see which environment variables Go is currently seeing, run go env.