Couldn't git push heroku master

Question

ruby 2.3.0 rails 5.0.3 Mac OS Sierra 10.12.5

I made rails app, and deployed.

git push heroku master

However, terminal said that

Gem::Ext::BuildError: ERROR: Failed to build gem native extension.
remote:        
remote:        current directory:
remote:        /tmp/build_4f29e71907fc179d3b55e72bff4e49ad/vendor/bundle/ruby/2.3.0/gems/rugged-0.25.1.1/ext/rugged
remote:        /tmp/build_4f29e71907fc179d3b55e72bff4e49ad/vendor/ruby-2.3.4/bin/ruby -r
remote:        ./siteconf20170615-225-sq7fnu.rb extconf.rb
remote:        checking for gmake... no
remote:        checking for make... yes
remote:        checking for cmake... no
remote:        ERROR: CMake is required to build Rugged.
remote:        *** extconf.rb failed ***
remote:        Could not create Makefile due to some reason, probably lack of necessary
remote:        libraries and/or headers.  Check the mkmf.log file for more details.  You may
remote:        need configuration options.
remote:        
remote:        Provided configuration options:
remote:        --with-opt-dir
remote:        --without-opt-dir
remote:        --with-opt-include
remote:        --without-opt-include=${opt-dir}/include
remote:        --with-opt-lib
remote:        --without-opt-lib=${opt-dir}/lib
remote:        --with-make-prog
remote:        --without-make-prog
remote:        --srcdir=.
remote:        --curdir
remote:        --ruby=/tmp/build_4f29e71907fc179d3b55e72bff4e49ad/vendor/ruby-2.3.4/bin/$(RUBY_BASE_NAME)
remote:        --use-system-libraries
remote:        
remote:        To see why this extension failed to compile, please check the mkmf.log which can
remote:        be found here:
remote:        
remote:        /tmp/build_4f29e71907fc179d3b55e72bff4e49ad/vendor/bundle/ruby/2.3.0/extensions/x86_64-linux/2.3.0/rugged-0.25.1.1/mkmf.log
remote:        
remote:        extconf failed, exit code 1
remote:        
remote:        Gem files will remain installed in
remote:        /tmp/build_4f29e71907fc179d3b55e72bff4e49ad/vendor/bundle/ruby/2.3.0/gems/rugged-0.25.1.1
remote:        for inspection.
remote:        Results logged to
remote:        /tmp/build_4f29e71907fc179d3b55e72bff4e49ad/vendor/bundle/ruby/2.3.0/extensions/x86_64-linux/2.3.0/rugged-0.25.1.1/gem_make.out
remote:        
remote:        An error occurred while installing rugged (0.25.1.1), and Bundler cannot
remote:        continue.
remote:        Make sure that `gem install rugged -v '0.25.1.1'` succeeds before bundling.
remote:  !
remote:  !     Failed to install gems via Bundler.
remote:  !
remote:  !     Push rejected, failed to compile Ruby app.
remote: 
remote:  !     Push failed
remote: Verifying deploy...
remote: 
remote: !       Push rejected to swtmp.
remote: 
To https://git.heroku.com/swtmp.git
 ! [remote rejected] master -> master (pre-receive hook declined)
error: failed to push some refs to 'https://git.heroku.com/swtmp.git'

I did 'gem install rugged' and 'bundle' but, this was not the solution.

Does anyone have the solution?

I installed cmake

$ brew install cmake
Warning: cmake 3.8.2 is already installed