対応方法 for failing to install mysqlclient on m2 Mac with ld: library not found for -lzlib

On an M2 Mac, when you run the following command:

pip install mysqlclient

You might encounter the following error:

      running build_ext
      building 'MySQLdb._mysql' extension
      creating build/temp.macosx-13-arm64-cpython-310
      creating build/temp.macosx-13-arm64-cpython-310/MySQLdb
      clang -Wno-unused-result -Wsign-compare -Wunreachable-code -fno-common -dynamic -DNDEBUG -g -fwrapv -O3 -Wall -isysroot /Library/Developer/CommandLineTools/SDKs/MacOSX13.sdk -I/opt/homebrew/opt/openssl/include -I/opt/homebrew/include -I/opt/homebrew/opt/zlib/include -Dversion_info=(2,1,1,'final',0) -D__version__=2.1.1 -I/opt/homebrew/Cellar/mysql/8.0.33/include/mysql -I/Users/yotsuyanagi/workspace/ranking-html-generator/.venv/include -I/opt/homebrew/opt/python@3.10/Frameworks/Python.framework/Versions/3.10/include/python3.10 -c MySQLdb/_mysql.c -o build/temp.macosx-13-arm64-cpython-310/MySQLdb/_mysql.o -std=c99
      clang -bundle -undefined dynamic_lookup -isysroot /Library/Developer/CommandLineTools/SDKs/MacOSX13.sdk -L/opt/homebrew/opt/openssl/lib -L/opt/homebrew/lib -L/opt/homebrew/opt/zlib/lib -I/opt/homebrew/opt/openssl/include -I/opt/homebrew/include -I/opt/homebrew/opt/zlib/include build/temp.macosx-13-arm64-cpython-310/MySQLdb/_mysql.o -L/opt/homebrew/Cellar/mysql/8.0.33/lib -L/opt/homebrew/opt/openssl@1.1/lib -lmysqlclient -lzlib -lresolv -o build/lib.macosx-13-arm64-cpython-310/MySQLdb/_mysql.cpython-310-darwin.so
      ld: warning: directory not found for option '-L/usr/local/opt/openssl/lib/'
      ld: warning: directory not found for option '-L/usr/local/opt/openssl/lib/'
      ld: library not found for -lzlib
      clang: error: linker command failed with exit code 1 (use -v to see invocation)
      error: command '/usr/bin/clang' failed with exit code 1
      [end of output]

  note: This error originates from a subprocess, and is likely not a problem with pip.
error: legacy-install-failure

× Encountered error while trying to install package.
╰─> mysqlclient

note: This is an issue with the package mentioned above, not pip.
hint: See above for output from the failure.

This error indicates that the installation failed.

Initially, I had the following environment variables set in .zshrc:

BREW_PREFIX=$(brew --prefix)
export LDFLAGS="-L${BREW_PREFIX}/opt/openssl/lib -L${BREW_PREFIX}/lib"
export CPPFLAGS="-I${BREW_PREFIX}/opt/openssl/include -I${BREW_PREFIX}/include"

When I added the following lines, the installation succeeded (the last two lines are the additions):

BREW_PREFIX=$(brew --prefix)
export LDFLAGS="-L${BREW_PREFIX}/opt/openssl/lib -L${BREW_PREFIX}/lib"
export CPPFLAGS="-I${BREW_PREFIX}/opt/openssl/include -I${BREW_PREFIX}/include"
export MYSQLCLIENT_LDFLAGS="${LDFLAGS} -L${BREW_PREFIX}/opt/zlib/lib"
export MYSQLCLIENT_CFLAGS="${CPPFLAGS} -I${BREW_PREFIX}/opt/zlib/include"

% pip install mysqlclient
Collecting mysqlclient
  Using cached mysqlclient-2.1.1-cp310-cp310-macosx_13_0_arm64.whl
Installing collected packages: mysqlclient
Successfully installed mysqlclient-2.1.1

Reference page:

https://github.com/Homebrew/homebrew-core/issues/130258

Addendum

Later, I encountered the following error:

clang -Wno-unused-result -Wsign-compare -Wunreachable-code -fno-common -dynamic -DNDEBUG -g -fwrapv -O3 -Wall -isysroot /Library/Developer/CommandLineTools/SDKs/MacOSX13.sdk -I/opt/homebrew/opt/openssl/include -I/opt/homebrew/include -Dversion_info=(2,1,1,'final',0) -D__version__=2.1.1 -I/opt/homebrew/opt/openssl/include -I/opt/homebrew/include -I/opt/homebrew/opt/zlib/include -I/Users/yotsuyanagi/workspace/manga-server-django/.venv/include -I/opt/homebrew/opt/python@3.9/Frameworks/Python.framework/Versions/3.9/include/python3.9 -c MySQLdb/_mysql.c -o build/temp.macosx-13-arm64-cpython-39/MySQLdb/_mysql.o -std=c99
MySQLdb/_mysql.c:29:10: fatal error: 'mysql.h' file not found
#include "mysql.h"
       ^~~~~~~~~
1 error generated.
error: command '/usr/bin/clang' failed with exit code 1
[end of output]

I found that mysql.h was located in:

/opt/homebrew/Cellar/mysql-client/8.0.33/include/mysql/
/opt/homebrew/Cellar/mysql/8.0.33/include/mysql/

After adding this path to MYSQLCLIENT_CFLAGS, the build succeeded:

BREW_PREFIX=$(brew --prefix)
export LDFLAGS="-L${BREW_PREFIX}/opt/openssl/lib -L${BREW_PREFIX}/lib"
export CPPFLAGS="-I${BREW_PREFIX}/opt/openssl/include -I${BREW_PREFIX}/include"
export MYSQLCLIENT_LDFLAGS="${LDFLAGS} -L${BREW_PREFIX}/opt/zlib/lib"
export MYSQLCLIENT_CFLAGS="${CPPFLAGS} -I${BREW_PREFIX}/opt/zlib/include -I${BREW_PREFIX}/Cellar/mysql/8.0.33/include/mysql"