I've worked around this by creating a ~/.ssh/config.d directory and splitting my configuration out into multiple files (normally by project). I then use dotdee[1] to watch that directory and automatically rebuild ~/.ssh/config anytime there is a change.

[1] https://launchpad.net/dotdee

I don't know of any, but one thing you can do is split up your config into multiple files and then use `cat` to combine them after making a change. There's also https://github.com/markhellewell/sshconfigfs

Here's what I put in my .bashrc:

  alias compile-ssh-config='echo -n > ~/.ssh/config && cat ~/.ssh/*.config > ~/.ssh/config'
  alias ssh='compile-ssh-config && ssh'

Compiles all your ~/.ssh/*.config files into a single ssh config file. It's simple and stupid and seems to do the trick.

I think storm[0] is what you are looking for.

[0] https://github.com/emre/storm

Aside from the ones already mentioned, there's a library called dot-ssh-config[1] that is useful for generating SSH configs.

[1] https://github.com/aelse/dot-ssh-config