This folder contains the source for a Cloud Function implementing a GitHub WebHook endpoint which can react to issues being labeled and send notifications to subscribers.

It also can inspect newly opened issues for specific keywords and treat matches as if a specific label was assigned to an issue.

Testing

To run local tests use test.sh script from this folder.

Deployment

To deploy use deploy.sh script.

Note that deploying requires configuring two environment variables:

• GITHUB_SECRET should be equal to the Hook Secret which you will use when creating a GitHub Hook at https://github.com/{org}/{repo}/settings/hooks
• SENDGRID_SECRET should be equal to SendGrid API secret which you get when you add SendGrid to your Cloud Project (see docs for the initial setup).

Firestore

Firestore needs to contain github-label-subscriptions collection.

The following Security Rules must be configured to ensure that each user can only edit its own subscriptions

rules_version = '2';
service cloud.firestore {
  match /databases/{database}/documents {
    match /github-label-subscriptions/{userId} {
      allow read, update, delete: if request.auth.uid == userId;
      allow create: if request.auth.uid != null;
    }

    match /github-keyword-subscriptions/{repo} {
      allow read: if true;
      allow write, create, update, delete: if false
    }

    match /{document=**} {
      allow read, write: if false;
    }
  }
}

Implementation Details

Subscriptions to labels are stored in the Firestore collection called github-label-subscriptions with each document at github-label-subscriptions/{userId} path has the following format

message Subscription {
    string email = 1;

    // Each subscription has format repo-name:label-name. For example
    // subscribing to label 'bug' in 'dart-lang/sdk' repo would be
    // recorded as 'dart-lang/sdk:bug'.
    repeated string subscriptions = 2;
}

Subscriptions are intended to be managed by users themselves so they are indexed by Firebase UID issued by Firebase authentification.

Subscriptions to keywords for specific repositories are stored at github-keyword-subscriptions/{repositoryName}, where {repositoryName} is full repository name with / replaced with $.

// Represents a subscription to keywords inside issue body. If the match is
// found then this is treated as if the issue is labeled with the given label.
message KeywordSubscription {
    string label = 1;
    repeated string keywords = 2;
}

Note: security rules prevent editing keyword subscriptions by anybody - so they can only be changed via Firebase Console UI.

Mails are sent via SendGrid.