Running ssh-agent on macOS Sierra

Previously macOS shipped with its own build of openssh that had some special additions to store the keys and passphrase in your keychain. They've finally come to their senses and reverted back to a more standard openssh. But this naturally cause some frustration when things stop working like they used to.

To mimic the same kind of functionality you have to instruct ssh to add your keys on startup, and alternatively store the passphrase in your keychain. In my opinion this is a lot cleaner approach than running ssh-add when you start a new shell, since you don't try to add them to ssh-agent every time.

Caution! When adding keys to your ssh-agent consider that any host you forward your keys to potentially will have access to these keys. You also potentially leak a lot of information about yourself when connecting to a host.

Host *
  IdentityFile  ~/.ssh/id_rsa
  UseKeychain    yes

  # Use with caution, see comment
  AddKeysToAgent yes