Git: access a remote repository over ssh using a key file but without using ~/.ssh/config

Question

Is it possible to access (fetch/push) a remote repository using ssh and an identity file (with the private key) without adding an entry in the file ~/.ssh/config such as:

Host tingle
  HostName 111.222.333.444
  User git
  IdentityFile c/tmp/my_id_rsa

Everything works fine when configuring the ~/.ssh/config file. However we have a script which clones from a remote repo, checks out, starts testing, commits results and pushes them. The script need to run on any machine without touching the ssh config file.

Answer 1

You can use the variable $GIT_SSH, see the documentation, to set a program that is invoked instead of ssh.

That way you can, e.g. do GIT_SSH=/my/own/ssh git clone https://my.own/repo.git

Adapt the contents of /my/own/ssh to your own need, e.g.:

#!/bin/bash
# Wrapper for ssh, to use identity file and known hosts file
exec /usr/bin/ssh -i /my/own/identity_file-o UserKnownHostsFile=/my/own/hosts.file "$@"

As far as I know this is currently the only way to do this without rather untidy path manipulations.

Answer 2

You could override the $GIT_SSH environment variable to use your own private key:

First, create a wrapper script. Let assume we call it gitssh.sh:

#!/bin/bash
ssh -i /path/to/mykey "$@"

Then, point $GIT_SSH to it:

export GIT_SSH=/path/to/gitssh.sh

Now, whenever you run a git command over ssh, it will be substituted with this script, and references your key.