[mac] bundle installでmysql2のインストールが失敗する

問題

bundle install時にMysql2の箇所でエラーが発生した。

/vendor/bundle/ruby/2.5.0/extensions/x86_64-darwin-17/2.5.0-static/mysql2-0.5.2/gem_make.out

checking for my_bool in mysql.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/vendor/bundle/ruby/2.5.0/gems/mysql2-0.5.2/ext/mysql2
make "DESTDIR=" clean

current directory: /path/vendor/bundle/ruby/2.5.0/gems/mysql2-0.5.2/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

解決策

xcodeをアップデートして、再実行で解決しました。

$ xcode-select --install
$ bundle install --path vendor/bundle