gem install mysql2

gistfile1.txt

➜  ~ gem install mysql2
Building native extensions.  This could take a while...
ERROR:  Error installing mysql2:
	ERROR: Failed to build gem native extension.

    current directory: /Users/rfoust/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/mysql2-0.4.5/ext/mysql2
/Users/rfoust/.rbenv/versions/2.3.1/bin/ruby -r ./siteconf20161030-77062-bxltsh.rb extconf.rb
checking for rb_absint_size()... yes
checking for rb_absint_singlebit_p()... yes
checking for ruby/thread.h... yes
checking for rb_thread_call_without_gvl() in ruby/thread.h... yes
checking for rb_thread_blocking_region()... no
checking for rb_wait_for_single_fd()... yes
checking for rb_hash_dup()... yes
checking for rb_intern3()... yes
checking for rb_big_cmp()... yes
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Using mysql_config at /usr/local/bin/mysql_config
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checking for mysql.h... yes
checking for SSL_MODE_DISABLED in mysql.h... yes
checking for SSL_MODE_PREFERRED in mysql.h... yes
checking for SSL_MODE_REQUIRED in mysql.h... yes
checking for SSL_MODE_VERIFY_CA in mysql.h... yes
checking for SSL_MODE_VERIFY_IDENTITY in mysql.h... yes
checking for errmsg.h... yes
checking for mysqld_error.h... yes
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Don't know how to set rpath on your system, if MySQL libraries are not in path mysql2 may not load
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Setting libpath to /usr/local/Cellar/mysql/5.7.16/lib
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creating Makefile

To see why this extension failed to compile, please check the mkmf.log which can be found here:

  /Users/rfoust/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/extensions/x86_64-darwin-16/2.3.0-static/mysql2-0.4.5/mkmf.log

current directory: /Users/rfoust/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/mysql2-0.4.5/ext/mysql2
make "DESTDIR=" clean

current directory: /Users/rfoust/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/mysql2-0.4.5/ext/mysql2
make "DESTDIR="
compiling client.c
compiling infile.c
compiling mysql2_ext.c
compiling result.c
compiling statement.c
linking shared-object mysql2/mysql2.bundle
ld: library not found for -lssl
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make: *** [mysql2.bundle] Error 1

make failed, exit code 2

Gem files will remain installed in /Users/rfoust/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/mysql2-0.4.5 for inspection.
Results logged to /Users/rfoust/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/extensions/x86_64-darwin-16/2.3.0-static/mysql2-0.4.5/gem_make.out