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 files for ruby at /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/include/ruby.h

I tried installing ruby with this: brew install rbenv ruby-build but this does not change anything.

Does anybody know how I can fix it?

Thanks!

Sun

I figured it out - after upgrading to Xcode 9 you must install the Command Line Tools for Xcode 9 as well. – Sun

Hit this issue when upgrading to Xcode 11 GM. Anyone found a solution? The sudo xcode-select --install command says I already have Command-Line Tools installed. Also tried manually downloading Xcode 11 Command-Line Tools from Developer Downloads. But I still get the error mkmf.rb can't find header files for ruby at /System/Library/Frameworks/Ruby.framework/Versions/2.3/usr/lib/ruby/include/ruby.h – Shirley

Answer 1

For Xcode 11 on macOS 10.14, this can happen even after installing Xcode and installing command-line tools and accepting the license with

sudo xcode-select --install
sudo xcodebuild -license accept

The issue is that Xcode 11 ships the macOS 10.15 SDK which includes headers for ruby2.6, but not for macOS 10.14's ruby2.3. You can verify that this is your problem by running

ruby -rrbconfig -e 'puts RbConfig::CONFIG["rubyhdrdir"]'

which on macOS 10.14 with Xcode 11 prints the non-existent path

/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.15.sdk/System/Library/Frameworks/Ruby.framework/Versions/2.3/usr/include/ruby-2.3.0

However, Xcode 11 installs a macOS 10.14 SDK within /Library/Developer/CommandLineTools/SDKs/MacOS10.14.sdk. It isn't necessary to pollute the system directories by installing the old header files as suggested in other answers. Instead, by selecting that SDK, the appropriate ruby2.3 headers will be found:

sudo xcode-select --switch /Library/Developer/CommandLineTools
ruby -rrbconfig -e 'puts RbConfig::CONFIG["rubyhdrdir"]'

This should now correctly print

/Library/Developer/CommandLineTools/SDKs/MacOSX10.14.sdk/System/Library/Frameworks/Ruby.framework/Versions/2.3/usr/include/ruby-2.3.0

Likewise, gem install should work while that SDK is selected.

To switch back to using the current Xcode 11 SDK, use

sudo xcode-select --switch /Applications/Xcode.app

Aarau

after export, it fixed the ruby -rrbconfig -e 'puts RbConfig::CONFIG["rubyhdrdir"]' but when I gem install, it still prints the wrong dir for file not found error – Monsignor

@Miranda can you verify that there's a ruby.h file in that path? Are you getting the exact same error message as in the question? What do xcodebuild -version and xcrun --show-sdk-version print? – Aarau

$ xcrun --show-sdk-version give xcodebuild: error: SDK "/Library/Developer/CommandLineTools/SDKs/MacOSX10.14.sdk/" cannot be located. xcrun: error: unable to lookup item 'SDKVersion' in SDK '/Library/Developer/CommandLineTools/SDKs/MacOSX10.14.sdk/', I end up using @bdorfman 's solution of rbenv – Monsignor

@Miranda thank you for your report, I was able to reproduce the problem while /Applications/Xcode.app is selected using xcode-select. Selecting the command-line tools SDK instead worked for me (setting the variable is no longer required). – Aarau

I searched for a couple of hours before finding this post, thank you. – Priestly

Accepting the license helped me install CocoaPods as well. Thank you. – Carthy

@Miranda run xcode-select --install to get Command Line Tools installed first. Then sudo xcode-select --switch /Library/Developer/CommandLineTools. That will resolve this error. (Shared for future Googlers.) – Bonar

Worked too on MacOS 10.15.7 and Xcode 11.7, I just had to run sudo xcode-select --switch /Applications/Xcode.app, because ruby -rrbconfig was printing the right path – Muro

I was having the same issue with Xcode 12.2 and because I named my Xcode 12.2 instead of the default Xcode, following these steps resolved my issue. Thank you. – Participate

Answer 2

None of the other solutions worked for me, here's what I ran to resolve the issue on Mac OS 10.14.x:

sudo rm -rf /Library/Developer/CommandLineTools
xcode-select --install
sudo xcodebuild -license accept
open /Library/Developer/CommandLineTools/Packages/macOS_SDK_headers_for_macOS_10.14.pkg

Tl

Thanks, nothing else worked for me with macOS 10.14.6. – Microcurie

This likewise fixed the issue for me after upgrading to Xcode 11 – Frontolysis

Gem install package on Xcode 11 and Mojave was failing. This answer got me going . Should be selected as answer. – Abide

This was the only thing that worked for me. This should be selected as the answer. I also tried the advise in this other thread to no avail (#26435142) before finding this answer. – Molecular

My issue was in regards to installing cocoapods, and this fixed it for me. macOS 10.14.5 xcode 11.3.1 Thanks! – Finder

You are a savior my friend – Blacksmith

Thx! This worked for me with MacOS 10.14.6 and Xcode 11.1 – Headgear

Awesome man, i can to this from another question and this is the only thing that worked for me on 10.14.6. Kudos :) – Tingly

Thank you so much for this. I spent over 7hours trying to solve this issue. – Melissiamelita

Thanks - this was the only thing that worked for me. 10.14.6. I first tried copying the Ruby 2.3 headers into the System Library Framework but SIP wouldn't let me. – Concentric

Answer 3

When upgrading XCode you need to install the Command-Line Tools and additionally accept the terms and conditions:

sudo xcode-select --install

Then:

sudo xcodebuild -license

Fowkes

The first command was enough to get docker-sync-stack stop complaining. Actually the second command failed with "xcode-select: error: tool 'xcodebuild' requires Xcode, but active developer directory '/Library/Developer/CommandLineTools' is a command line tools instance" – Melisenda

As @Melisenda said, it seems like the second command doesn't work, but thankfully it wasn't necessary to get docker-sync start to stop complaining. – Gramophone

This wasn't enough for me, unfortunately. – Tl

Answer 4

As of Xcode 11, it seems like the ruby development headers are no longer included, so you will need to manually install them outside of Xcode Command Line Tools.

E.g. for me using rbenv i did

rbenv install 2.6.4
rbenv global 2.6.4
eval "$(rbenv init -)"

Then ran bundle install and everything worked as expected.

Harbard

Most importantly this worked for me. I'd also like to also note by adding rbenv in my CI workflow I was able to make great improvements (no need to install bundler using sudo anymore!) Thanks a lot @Harbard – Handbreadth

This doesn't work for me for some reason. I even tried replacing "2.6.4" with "2.3.0". When I look, there is no /System/Library/Frameworks/Ruby.framework/Versions/2.3/usr/lib/ruby/include directory though the path up to "include" does exist. – Ionia

thanks but I had to install the gem again, since there is nothing to bundle for docker-sync. The answer from @fnordl worked for me. – Sarrusophone

@DarrellBrogdon Your environment probably isnt set up right. If its working correctly mkmf wont be looking for 2.3 any more itll be looking for whichever version you set. If you're still getting an error with the path /System/Library/Frameworks/Ruby.framework/Versions/2.3 it indicates that your env is still using the macOS system ruby and not rbenv's. – Harbard

This also solved my Docker x Ruby issues – Ptero

Answer 5

For Xcode 11 I fixed this by also installing of /Library/Developer/CommandLineTools/Packages/macOS_SDK_headers_for_macOS_10.14.pkg package.

Heavyarmed

Hey, I don't have this file. Where can I find it ? – Sarrusophone

Verify the pkg exists at the path Sergey provided. Check the path from root. Not in your users path. If is not there you can attempt to first install the command line tools: xcode-select --install and it should show up. Then, once you have the package at that path force the install like so sudo installer -pkg macOS_SDK_headers_for_macOS_10.14.pkg -target / (executing from /Library/Developer/CommandLineTools/Packages) – Taeniacide

Answer 6

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.

Buckwheat

This fixed the problem for me. – Ganges

Didn't work for me. I am prompted to add -allowUntrusted flag. But then it still failed at the end. The error message is installer: The install failed (The Installer encountered an error that caused the installation to fail. Contact the software manufacturer for assistance.) – Wilkison

after trying every thing, you saved my life man thanks – Hoax

Answer 7

I had the same problem while installing fastlane. The tadman's answer is correct, but the command lines don't work for me with Xcode 10.2.1 (I'm not sure with other versions). You need to open Xcode, then open Preferences, select Locations and choose Command Line Tools. In my case, Command Line Tools field is empty.

Schwejda

This worked for me after searching for hours. Thanks! – Tamworth

Thanks alot Man, this worked for me too. My Xcode version is also 10.2.1 – Geelong

Answer 8

As @bdorfman said in his comment, the Ruby headers are no longer included as of Xcode 11 build but they seem to try to make a new build for this as soon as possible (?): https://discuss.circleci.com/t/xcode-11-gm-seed-2-released/32505/12.

What worked for me was to use rbenv like @bdorfman said:

rbenv install 2.6.4
rbenv global 2.6.4
eval "$(rbenv init -)"

But with the extra step of adding docker-sync to your new ruby version. Since after you change the ruby version (for example)

$ ruby -v
ruby 2.6.4p104 (2019-08-28 revision 67798) [x86_64-darwin18]

And then running gem list:

$ gem list
bigdecimal (default: 1.4.1)
bundler (default: 1.17.2)
cmath (default: 1.0.0)
csv (default: 3.0.9)
date (default: 2.0.0)
dbm (default: 1.0.0)
did_you_mean (1.3.0)
e2mmap (default: 0.1.0)
etc (default: 1.0.1)
fcntl (default: 1.0.0)
fiddle (default: 1.0.0)
fileutils (default: 1.1.0)
forwardable (default: 1.2.0)
io-console (default: 0.4.7)
ipaddr (default: 1.2.2)
irb (default: 1.0.0)
json (default: 2.1.0)
logger (default: 1.3.0)
matrix (default: 0.1.0)
minitest (5.11.3)
mutex_m (default: 0.1.0)
net-telnet (0.2.0)
openssl (default: 2.1.2)
ostruct (default: 0.1.0)
power_assert (1.1.3)
prime (default: 0.1.0)
psych (default: 3.1.0)
rake (12.3.2)
rdoc (default: 6.1.2)
rexml (default: 3.1.9)
rss (default: 0.2.7)
scanf (default: 1.0.0)
sdbm (default: 1.0.0)
shell (default: 0.7)
stringio (default: 0.0.2)
strscan (default: 1.0.0)
sync (default: 0.5.0)
test-unit (3.2.9)
thwait (default: 0.1.0)
tracer (default: 0.1.0)
webrick (default: 1.4.2)
xmlrpc (0.3.0)
zlib (default: 1.0.0)

(does not contains docker-sync)

If you run the gem install for docker-sync you will use the docker-sync for your rbenv managed ruby.

$ gem install docker-sync

Stiver

Answer 9

If you want to get a deeper insight into the issue:

Mac OS X 10.14 has stopped placing the include libraries in their usual location, /usr/include, keeping them only inside the XCode directory.

To confirm that this is the problem, simply run ls /usr/include. If the result comes out empty, its really this problem.

Apple ships a “legacy installer” for you to be able to install the headers in the “old location”. To fix the problem just run this:

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

https://silvae86.github.io/sysadmin/mac/osx/mojave/beta/libxml2/2018/07/05/fixing-missing-headers-for-homebrew-in-mac-osx-mojave/

Jejunum

Answer 10

Running open /Library/Developer/CommandLineTools/Packages/macOS_SDK_headers_for_macOS_10.14.pkg in the terminal opens the package installation wizard. After properly installing was I able to proceed.

MacOS 10.4.4

Heptachord

Answer 11

Open Terminal

xcode-select --install
sudo xcodebuild -license accept
curl -L https://get.rvm.io | bash -s stable

Close and Reopen Terminal

rvm install ruby-2.6

sudo gem install cocoapods
pod install 

After completing right click on project top-left on android studio then click on Flutter -> Open IOS Module in Xcode

Varro