Docker for Mac - mkmf.rb can't find header files for ruby

Question

I updated XCode on my Mac and since then when starting Docker using docker-sync-stack start I get this error message:

mkmf.rb can\'t find header         


        

Answer 1

Single line command fix:

On OSX Mojave I ran the following command:

sudo installer -pkg /Library/Developer/CommandLineTools/Packages/macOS_SDK_headers_for_macOS_10.14.pkg -target /

and it fixed the issue.