gemのmysql2をインストールする際にハマったのでメモ
エラーログ
Fetching mysql2 0.3.21
Installing mysql2 0.3.21 with native extensions
Gem::Ext::BuildError: ERROR: Failed to build gem native extension.
current directory: /path/to/vendor/bundle/ruby/2.4.0/gems/mysql2-0.3.21/ext/mysql2
/path/to/.rbenv/versions/2.4.1/bin/ruby -I /path/to/.rbenv/versions/2.4.1/lib/ruby/site_ruby/2.4.0 -r ./siteconf20190218-87873-15epx9f.rb extconf.rb
--with-cppflags\=-I/usr/local/opt/openssl/include
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
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Using mysql_config at /usr/local/opt/mysql@5.7/bin/mysql_config
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checking for 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/opt/mysql@5.7/lib
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creating Makefile
current directory: /path/to/vendor/bundle/ruby/2.4.0/gems/mysql2-0.3.21/ext/mysql2
make "DESTDIR=" clean
current directory: /path/to/vendor/bundle/ruby/2.4.0/gems/mysql2-0.3.21/ext/mysql2
make "DESTDIR="
compiling client.c
compiling infile.c
compiling mysql2_ext.c
compiling result.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 /path/to/vendor/bundle/ruby/2.4.0/gems/mysql2-0.3.21 for inspection.
Results logged to /path/to/vendor/bundle/ruby/2.4.0/extensions/x86_64-darwin-18/2.4.0-static/mysql2-0.3.21/gem_make.out
An error occurred while installing mysql2 (0.3.21), and Bundler cannot continue.
Make sure that `gem install mysql2 -v '0.3.21' --source 'https://rubygems.org/'` succeeds before bundling.
In Gemfile:
mysql2
パスが通っていないのが原因
bundle config --local build.mysql2 "--with-ldflags=-L/usr/local/opt/openssl/lib"