scripting your .ssh/config with scheme

Generating config files via programs is an old trick which I'm not going to rediscover now. But this one is my first scheme script I wrote for that purpose.

It's about generating a config file you ought to put in your ~/.ssh/config , so that there are some sane defaults when you are ssh-ing to your servers.



It's using the amazon cli interface to fetch the instances of your aws infrastructure. Then, concatenating it with a list of custome servers, and that's basically it (I'm using chicken scheme here, with the regex module which you can get via chicken-install):

	;; sudo chicken-install shell
	;; csi -ss ~/bin/generate-ssh-config-file.scm >~/.ssh/config
	(use shell)
	(define servers
	(string-split
	(capture "aws ec2 describe-instances --output text | grep TAGS | grep Name | cut -f3")))
	(define special-servers
	'(("user1" "host" "hostname")))
	(define (print-formatted server)
	(let ((user (car server))
	(host (cadr server))
	(hostname (caddr server)))
	(print "host " host)
	(print "hostname " hostname)
	(print "user " user)))
	(define (main args)
	(map print-formatted
	(append
	(map (lambda (server)
	(list "rgrau" server server))
	servers)
	special-servers)))

view raw generate-ssh-config-file.scm hosted with ❤ by GitHub

With just this, you can already ssh to the servers and have your username filled in, or have your aliases in there.

Also, as I'm super super lazy, I also have a readily available command to prompt me for the server I want to ssh to, and make it ssh there. Quite simple stuff, but hey, it works :)

urxvt -e ssh $(grep 'host ' .ssh/config | awk '{print $2}' | dmenu -l 10)