bundle install 時にmysql2のインストールがエラーになる #Rails

bundle install時にだいたいmysql2のインストールがエラーになるのでメモ
※M1 mac book airにて動作

大体こんなエラーが出る

Make sure that `gem install mysql2 -v '0.5.3' --source 'https://rubygems.org/'` succeeds before bundling.

open sslの設定が必要なので、以下の順番に調べて設定

$ brew info openssl
openssl@1.1: stable 1.1.1k (bottled) [keg-only]
Cryptography and SSL/TLS Toolkit
https://openssl.org/
/opt/homebrew/Cellar/openssl@1.1/1.1.1k (8,071 files, 18MB)
  Poured from bottle on 2021-05-12 at 21:01:47
From: https://github.com/Homebrew/homebrew-core/blob/HEAD/Formula/openssl@1.1.rb
License: OpenSSL
==> Caveats
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"        ← ここが重要
  export CPPFLAGS="-I/opt/homebrew/opt/openssl@1.1/include".  ← ここが重要

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"

==> Analytics
install: 803,075 (30 days), 2,624,782 (90 days), 8,822,713 (365 days)
install-on-request: 62,439 (30 days), 260,077 (90 days), 1,146,614 (365 days)
build-error: 0 (30 days)

上の調べた結果を設定して解決

$ bundle config --local build.mysql2 "--with-cppflags=-I/opt/homebrew/opt/openssl@1.1/include"
$ bundle config --local build.mysql2 "--with-ldflags=-L/opt/homebrew/opt/openssl@1.1/lib"