Authentication on Heroku uses one of three mechanisms, depending on the situation:

• Email and password
• API token
• SSH key

The email address and password are used by the heroku command to obtain an API token. This token is used for authentication in all other Heroku API requests, and can be regenerated at will by the user, in the heroku.com web interface. Regenerating an API token invalidates the current token and creates a new one.

The SSH key is used for git push authentication when using SSH Git transport. You can use heroku keys to manage your SSH keys on Heroku.

API token storage

The Heroku command-line tool stores API tokens in the standard Unix file ~/.netrc ($HOME\_netrc on Windows).

The netrc format is well-established and well-supported by various network tools on unix. With Heroku credentials stored in this file, other tools such as curl can access the Heroku API with little or no extra work. When using the default HTTP transport, Git uses cURL, and cURL will use the API key stored in .netrc to authenticate with the Heroku HTTP Git service.

Tips:Setting the HEROKU_API_KEY environment variable on your machine will interfere with normal functioning of auth commands from Toolbelt.

Usage examples

Running heroku login (or any other heroku command that requires authentication) will create or update your ~/.netrc:

$ ls .netrc
ls: .netrc: No such file or directory
$ heroku login
Enter your Heroku credentials.
Email: me@example.com
Password:
$ cat .netrc
machine api.heroku.com
  login me@example.com
  password c4cd94da15ea0544802c2cfd5ec4ead324327430
machine git.heroku.com
  login me@example.com
  password c4cd94da15ea0544802c2cfd5ec4ead324327430
$

Retrieving the API token

You can display the token via the CLI:

$ heroku auth:token
c4cd94da15ea0544802c2cfd5ec4ead324327430

Authenticating with the API token

Having logged in, you can use curl to access the Heroku API:

$ curl -H "Accept: application/json" -n https://api.heroku.com/apps

You can also create a file ~/.curlrc, containing extra command-line options for curl:

~/.curlrc

--netrc
--header "Accept: application/json"

With this file, the command is simply:

$ curl https://api.heroku.com/apps

File format

The file contains a list of free-form records and comments. Comments start with a # (hash) symbol and continue to the end of the line. Each record is of the form:

machine api.heroku.com
  login me@example.com
  password ABC123

One other type of record, macdef, can appear in .netrc files, but it is not commonly used and is ignored by the heroku command.