Use Custom SSH key buildpack if you need to, for example, download a dependency stored in a private repository.

Based on http://stackoverflow.com/a/29677091/3303182.

• Add the buildpack to your app: heroku buildpacks:add --index 1 https://github.com/simon0191/custom-ssh-key-buildpack

• Generate a new SSH key (https://help.github.com/articles/generating-a-new-ssh-key-and-adding-it-to-the-ssh-agent/)

  For this example I will assume that you named the key deploy_key.

• Add the ssh key to your private repository account.

  • Github: https://help.github.com/articles/adding-a-new-ssh-key-to-your-github-account/

  • Bitbucket: https://confluence.atlassian.com/bitbucket/add-an-ssh-key-to-an-account-302811853.html

• Encode the private key as a base64 string and add it as the CUSTOM_SSH_KEY environment variable of the heroku app.

• Make a comma separated list of the hosts for which the ssh key should be used and add it as the CUSTOM_SSH_KEY_HOSTS environment variable of the heroku app.

  # OSX
  $ heroku config:set CUSTOM_SSH_KEY=$(base64 --input ~/.ssh/deploy_key) CUSTOM_SSH_KEY_HOSTS=bitbucket.org,github.com
  
  # Linux
  $ heroku config:set CUSTOM_SSH_KEY=$(base64 ~/.ssh/deploy_key) CUSTOM_SSH_KEY_HOSTS=bitbucket.org,github.com
  

• Deploy your app and enjoy :)

I needed to install dependencies stored in private repositories but I didn't want to hardcode passwords in the code. I found a solution in StackOverflow but it only worked for the node buildpack so I decided to create this technology agnostic buildpack.