If you’re using OpenSSH, the IdentityFile configuration directive selects the SSH key to use.

Add something like this to your SSH config file (~/.ssh/config):

Host github.com
  IdentityFile ~/.ssh/github_rsa

Host gitlab.com
  IdentityFile ~/.ssh/gitlab_rsa

This will use the github_rsa key for repositories hosted at github.com, and the gitlab_rsa key for repositories hosted at gitlab.com. Adjust as needed for your key names and hosts, obviously.

you dont have to switch

git will automatically select one that works

I have the same password protected ssh key for every git site i am on tho. The sites only know the public key so its fine.

have at it!

taken from Gitlab’s manual page for creating a key, but i wonder what else could be done to expand on it.

#~/.gitconfig
[includeIf "hasconfig:remote.*.url:https://gitlab.com/**"]
path = /path/to/gitlab.gitconfig
[includeIf "hasconfig:remote.*.url:https://github.com/**"]
path = /path/to/github.gitconfig

#example gitlab gitconfig from the included path
[user]
name = Your Name
email = [email protected]
signingkey = 0000999988887777

[commit]
gpgsign = true

if all works well, Git should be able to automatically use the selected key depending on the repo’s stated remote server.