Heroku buildpack to let you add an SSH private key to an heroku app so it can access private GitHub repositories during bundle install
Create a GIT_DEPLOY_KEY environment variable with the private key that you registered on your Heroku
Heroku Instructions
I do
heroku config:set GIT_DEPLOY_KEY="`cat /path/to/key`"
Optionally configure GIT_HOST, GIT_USER and GIT_HOST_HASH. If not provided, they will default to github.com,git and github hashes respectively.
heroku config:set GIT_HOST=my-git-host.example.com
heroku config:set GIT_USER=git-party
heroku config:set GIT_HOST_HASH="git-host.example.com ssh-rsa AAABBBCCC...CCCXXX"
Getting the host key can be a pain so the following is a quick and dirty solution; 1st backup and clear out your ~/.ssh/known_hosts file, then connect to each host with ssh, which will prompt you with host hash fingerprint. Verify these and accept the connection. When you're done doing that you can do
heroku config:set GIT_HOST_HASH="`cat ~/.ssh/known_hosts`"
Then restore your known_hosts backup file.
Use this custom repository as custom buildpack for heroku deployment. This buildpack should be executed first as it takes care of setting up the SSH environment, for accessing private repos.
heroku buildpacks:set --index 1 "https://github.com/siassaj/heroku-buildpack-git-deploy-keys.git#master"
heroku buildpacks:add 'heroku/ruby'
The --index 1 tells heroku to run this custom buildpack before other buildpacks.
Read more about using third-party buildpacks in heroku https://devcenter.heroku.com/articles/third-party-buildpacks#using-a-custom-buildpack
heroku buildpacks:add 'heroku/ruby' tells heroku to use the default buildpack for Ruby applications.
Use the appropriate buildpack for your application.
Default buildpacks available in Heroku https://devcenter.heroku.com/articles/buildpacks#officially-supported-buildpacks
Testing on your local machine with the test runner will clobber ~/.ssh/known_hosts and ~/.ssh/private_key file if they exist. I just destroyed my ~/.ssh/id_rsa and ~/.ssh/known_hosts testing this. I renamed the key being used to private_key (also because we can't be sure it'll be an RSA id anyway) so it should be less devastating but you've been warned. Best is probably to chmod everything in ~/.ssh to 0400.
A great way to test is using Heroku's buildpack test runner. See https://github.com/heroku/heroku-buildpack-testrunner. To set up, run these commands:
This package draws very heavily from https://github.com/fs-webdev/heroku-buildpack-ssh-keys That project's gone now, but I'd still like to thank it's main writer Tim Shadel (https://github.com/timshadel) for the work.