Build Script Notes

Notes, neat things, and gotchas about building and packaging a Go executable for the Mac App Store. This is based on the bampf project build at https://github.com/gazed/bampf/blob/master/build

Notes

• The build script was written in Python as it either already available or easily installed on OS X, Windows, and Linux. Python is mainly used to execute the individual shell commands needed to create the final product.
• The build script attempts to be maintainable in two ways: first, it is kept short at around 150 lines, and second many of the individual commands can be tested simply by pasting from the script to the command line.
• Tools other than go were needed for the final OS X Application. The OS X command line tools are needed for compiling, Xcode was used to create developer signing keys, and OS X Application Loader was used to submit the executable for App store approval.
• Product resources, like icons, are stored in the bampf/src directory. This seemed a handy place to keep product related stuff without cluttering the top directory, bampf, or the code directory, bampf/src/bampf.

Neat things

• buildBinary (line 53): Its nice to be able to inject a version number into the executable during the build. In this case the version comes from source control tags, git for this project, combined with the go build -X flag.
• buildWindows (line 110): Sometimes it can be easier to ship a single executable. Zip was used combine the game resources with the go executable into a single binary. At runtime, the go executable is able to open itself to read the zipped resources.

Gotchas

• buildOSX (line 68): Needed -linkmode=external build flag as Apple looks for some system specific fields in the executable. Details in go issue 6198.
• buildOSX (lines 73-80): Mac applications need to conform to a particular directory structure.
• buildOSX (lines 88-93): Mac applications have a particular file mode that can copied from an existing Mac app.
• Application signing is a must. Add the following lines at the end of the buildOSX method. Edit to replace XXX and YYY with the names of your developer OS X keys.

    # create two signed versions.  One for self distribution, one for the app store.
    signOsx('target', '"Developer ID Application: XXX"', '"Developer ID Installer: XXX"')
    signOsx('target/app', '"3rd Party Mac Developer Application: YYY"', '"3rd Party Mac Developer Installer: YYY"')

def signOsx(outdir, akey, ikey):
    subprocess.call(shlex.split('codesign -fv --entitlements src/Entitlements.plist -s '+akey+' '+outdir+'/Bampf.app'))
    subprocess.call(shlex.split('productbuild --version 1.0 --sign '+ikey+' --component '+outdir+'/Bampf.app /Applications '+outdir+'/Bampf.pkg'))

Caveats: while the script can also build a Windows executable when on a windows OS, it is not at the point where the application can be submitted to the Windows App store. Also Linux builds are stubbed at the moment.