ssh-url-with-ssh-key

#!/bin/bash
if [[ "$1" == --help ]] ; then
  sed -e 's/^  //' <<EOF
  $0 is a wrapper for ssh that extracts a base64 encoded SSH key
  from the SSH user~key@host URL and launches SSH with that key.

  Set the GIT_SSH environment variable to this script ($0)
  to activate it for your git usage.

  Usage:

  $0 [--help | --create | user~key@host] [command]

  --create    Create a new private and public SSH key. This will print
              out the private key as you should append it to the SSH
              user and the public key to add to a remote system.

  Example usage:

  GIT_SSH=$0 git clone git~LS0tLS1CRUdJTiBP....SDFWENF324DS=@github.com:user/repo.git

  $0 user~LS0tLS1CRUdJTiBP....SDFWENF324DS=@host


  Written to support GitHub Deploy Keys with tools that cannot manage
  SSH keys but only offer to store a GitHub URL.

  License: © 2017 Schlomo Schapiro, Zalando SE

  Permission is hereby granted, free of charge, to any person obtaining a
  copy of this software and associated documentation files (the "Software"),
  to deal in the Software without restriction, including without limitation
  the rights to use, copy, modify, merge, publish, distribute, sublicense,
  and/or sell copies of the Software, and to permit persons to whom the
  Software is furnished to do so, subject to the following conditions:

  The above copyright notice and this permission notice shall be included
  in all copies or substantial portions of the Software.

  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
  WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR
  IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
EOF
elif [[ "$1" == --create ]] ; then
  shift
  key_file=$(mktemp -u)
  trap "rm -f $key_file" EXIT
  ssh-keygen -q -b 256 -t ecdsa -N "" -C "$*" -f $key_file
  echo Append this base64-encoded private key to the username:
  echo "~$(base64 <$key_file | tr -d "\n\r")"
  echo Public Key:
  cat $key_file.pub
elif [[ "$1" == *~*@* ]] ; then
  IFS="~@" read user key host <<<"$1"
  shift
  remote="$user@$host"
  key_file=$(mktemp)
  trap "rm -f $key_file" EXIT
  base64 -d <<<"$key" >$key_file
  ssh -i $key_file "$remote" "$@"
else
  exec ssh "$@"
fi