While yes you can subscribe to a GitHub Issue for notifications, this is only after the Issue has been created. And sometimes you don't want all the details. This was designed to monitor a specific label when it is applied to an issue (like a breaking change notification) and notify a set of recipients with the details of the issue.

The following variables are required to be set:

• API Key for SendGrid (Get free API key). Set this in environment variable as SENDGRID_API_KEY. I recommend putting this in your repos Settings > Secrets and using like below.

You can now consume the action by referencing the v1 branch

uses: timheuer/issue-notifier@v1
env:
  SENDGRID_API_KEY: ${{ secrets.SENDGRID_API_KEY }}
with:
  fromMailAddress: 'no-reply@example.com'
  toMailAddress: 'example@example.com'
  subject: 'A new issue was labeled'
  labelsToMonitor: 'breaking-change,major-bug'