I have a github repo that I want to push to a heroku node. A 3rd host will be co-ordinating this. As I\'m going to be doing this on a large scale I want to avoid having to d
Codeship.io does this as a service now, and automatically configures the appropriate git webhooks on public or private github repos.
There are a few other "continuous integration as a service" (CIAAS) options out there, but in general they get around the problem you're specifically presenting: web hooks need to hit a 3rd-party service, which in turn can trigger the heroku build process.
These CIAAS hosts act as the 3rd-party, and usually offer a free tier for public projects. You can also roll your own by deploying a web hook receiving server, which can both pull and push git repos.