Heroku Cloudflare App Domain

Creating branded herokuapp.com-like domains using Cloudflare, based on the app name (eg my-app-prod.example.com).

Features

• Set records for domains which don't exist
• Update records which are set incorrectly
• Delete records which aren't referenced any more in Heroku
• Enable / refresh ACM when an app has its domain updated.

Usage

Install the dependencies listed in requirements.txt, ideally into a virtual environment.

Set some environment variables:

• CF_API_KEY: A Cloudflare API key, with access to the zone you wish to edit. "DNS Edit" is required for those zones.
• HEROKU_API_KEY: API key from Heroku
• CF_ZONE_ID: The Cloudflare zone id of the domain to automatically create

Optionally:

• APP_NAME: A regex of app names to act on. Any not matching this will be skipped.
• HEROKU_TEAMS: A comma separated list of Heroku teams to operate on. By default will use all apps the account has access to.
• ALLOWED_CNAME_TARGETS: A comma-separated list of regexes which match CNAMEs. If these CNAMEs are found in place of the correct Heroku CNAME, they won't be overridden.

These can also be set in a .env file.

Then, simply run the main.py. To have the application loop for you, specify an interval in seconds with $INTERVAL.

Deployment

In some hosting environments, it may not be possible to run the container as a background job (eg Cloud Run).

To account for this, the default container wraps the command in webhook.

To trigger the hook, send a GET request to /hooks/trigger. The webhook is protected by a token, which can be set using $WEBHOOK_TOKEN, and should be sent in the X-Webhook-Token header.

To run in a loop instead of a webhook, set $INTERVAL in the container.

Alternatively, it's possible to run on Heroku using its scheduler. Just add a job for /app/main.py, and stop the web processes.