How Do I Get Git to Default to Ssh and Not Https for New Repositories

• GitHub

  git config --global url.ssh://git@ 
  

• BitBucket

  git config --global url.ssh://git@ 
  

That tells git to always use SSH instead of HTTPS when connecting to GitHub/BitBucket, so you'll authenticate by certificate by default, instead of being prompted for a password.

The response provided by Trevor is correct.

But here is what you can directly add in your .gitconfig:

# Enforce SSH
[url "ssh://git@"]
  insteadOf = 
[url "ssh://git@"]
  insteadOf = 
[url "ssh://git@"]
  insteadOf = 

You need to clone in ssh not in https.

$ ssh-keygen -t ed25519 -C ""

Add content of ~/.ssh/id_rsa.pub to your ssh keys on github.com.

If you need to have separate keys for different hosts, you can use this script:

#!/usr/bin/env bash

if [ $# -lt 2 ]; then
  echo "Provide email and hostname"
  exit 1
fi

email="$1"
hostname="$2"
keypath="$HOME/.ssh/${hostname}_rsa"
ssh-keygen -t ed25519 -C $email -f $keypath

if [ ! $? -eq 0 ]; then
  echo "Error when running ssh-keygen"
  exit 1
fi

exit 0
cat >> $HOME/.ssh/config <<EOF
Host $hostname
        Hostname $hostname *.$hostname
        User git
    IdentitiesOnly yes
        IdentityFile $keypath
EOF

and run it like

bash generate_ssh.sh  github.com

Change your remote url

git remote set-url origin :user/foo.git

(or just edit .git/config)

Add content of ~/.ssh/github.com_rsa.pub to your ssh keys on github.com

Check connection

ssh -T 

You may have accidentally cloned the repository in https instead of ssh. I've made this mistake numerous times on github. Make sure that you copy the ssh link in the first place when cloning, instead of the https link.

SSH File

~/.ssh/config file
Host *
    StrictHostKeyChecking no
    UserKnownHostsFile=/dev/null
    LogLevel QUIET
    ConnectTimeout=10
Host github.com
        User git
        AddKeystoAgent yes
        UseKeychain yes
        Identityfile ~/github_rsa

Edit reponame/.git/config

[remote "origin"]
        url = :username/repo.git

FYI - I'm using this due to github no longer allowing ssh:

[url ":"]
    insteadOf = 
[url ":"]
    insteadOf = 

While the other answers here directly answer the titular question (in a way that I didn't know was possible! TIL something new about git!) about automagically turning https based remotes into git+ssh ones, the "normal" way to do this "right" from the start is to not give git the https url.

GitHub (along with other popular git hosting services) always has a little button that lets you get the URL that git should clone. You just need to click the small "SSH" button:

Alternatively for a new project

Once you select the "SSH" option, GitHub (and others) will remember (as long as you're logged in) and make it the default in the future.