macでpip install psycopg2が通らない時

macにposgreをインストールして、djangoと連携させたいだけだったんです。

    ld: library not found for -lssl
    clang: error: linker command failed with exit code 1 (use -v to see invocation)
    error: command '/usr/bin/clang' failed with exit code 1

こんなメッセージがでてきて悲しいとき。

結論

export LDFLAGS="-L/opt/homebrew/opt/openssl@1.1/lib"
export PKG_CONFIG_PATH="/opt/homebrew/opt/openssl@1.1/lib/pkgconfig"
export CPPFLAGS="-I/opt/homebrew/opt/openssl@1.1/include"

を叩いたらいけた。

もともとPostgreSQLをインストールしたときに、

==> openssl@1.1
A CA file has been bootstrapped using certificates from the system
keychain. To add additional certificates, place .pem files in
  /opt/homebrew/etc/openssl@1.1/certs

and run
  /opt/homebrew/opt/openssl@1.1/bin/c_rehash

openssl@1.1 is keg-only, which means it was not symlinked into /opt/homebrew,
because macOS provides LibreSSL.

If you need to have openssl@1.1 first in your PATH, run:
  echo 'export PATH="/opt/homebrew/opt/openssl@1.1/bin:$PATH"' >> ~/.zshrc

For compilers to find openssl@1.1 you may need to set:
  export LDFLAGS="-L/opt/homebrew/opt/openssl@1.1/lib"
  export CPPFLAGS="-I/opt/homebrew/opt/openssl@1.1/include"

For pkg-config to find openssl@1.1 you may need to set:
  export PKG_CONFIG_PATH="/opt/homebrew/opt/openssl@1.1/lib/pkgconfig"

というメッセージがでてたはずなのでそれを叩いた上で pip install したらいけたというオチ。