pubsub-webhook

Convert webhooks requests to PubSub messages.

This is a Google Cloud Function that takes an incoming HTTP POST payload and forwards it to a Pub/Sub topic. That's it. It's particularly useful if you want to serve a single webhook on Google Cloud and have it trigger multiple subscribers, whether it be Cloud Functions or App Engine applications, or anything else subscribing to the topic.

Requirements

• Google Cloud

Installation

Set some environment variables first:

• GOOGLE_CLOUD_PROJECT: the project in which to deploy the function
• TOPIC_NAME: the Pub/Sub topic to which to forward the POST payloads
• TOPIC_PROJECT: (optional) the project hosting the Pub/Sub topic; the default is the same project as the function
• IP_WHITELIST: (optional) comma delimited list of IP ranges from which the HTTP POST must originate, e.g. 1.2.3.4/32,1.2.3.5/24; defaults to allowing all requests

Create Topic

Create a Cloud Pub/Sub topic:

gcloud pubsub topics create $TOPIC_NAME

Configure IAM

Create a new service account for use by the Cloud Function:

gcloud iam service-accounts create webhook

Grant permissions to publish to the topic:

gcloud pubsub topics add-iam-policy-binding $TOPIC_NAME \
    --member "serviceAccount:webhook@${GOOGLE_CLOUD_PROJECT}.iam.gserviceaccount.com" \
    --role roles/pubsub.publisher \
    --project $TOPIC_PROJECT

Deploy

gcloud beta functions deploy webhook \
     --source . \
     --runtime python37 \
     --entry-point pubsub_webhook \
     --service-account webhook@${GOOGLE_CLOUD_PROJECT}.iam.gserviceaccount.com \
     --set-env-vars TOPIC_NAME=${TOPIC_NAME},TOPIC_PROJECT=${TOPIC_PROJECT},IP_WHITELIST=${IP_WHITELIST} \
     --trigger-http \
     --allow-unauthenticated

Test

Run an integration test against a deployed function:

make integration

Ensure you've set the environment variable TOPIC_NAME first.