webhook-processor

Webhook Processor

A webhook ingestion and processing system built with Encore.ts, demonstrating Pub/Sub fan-out patterns.

Architecture

This app has three services:

• ingest — Receives webhooks via HTTP, validates signatures, and publishes events to a Pub/Sub topic.
• processor — Subscribes to the topic, stores all events in Postgres, and exposes a query API.
• notifications — Subscribes to the same topic independently, stores important events (payments, releases, etc.) and provides stats. Demonstrates the fan-out pattern.

Both processor and notifications receive every event, but handle them differently. This is the fan-out pattern — one event published, multiple subscribers process it independently.

Getting Started

1. Optionally set webhook secrets for signature validation:

encore secret set --type dev,local,pr,prod WebhookSecretStripe
encore secret set --type dev,local,pr,prod WebhookSecretGitHub

2. Run the app:

encore run

The Postgres databases are provisioned automatically on startup. No manual database setup required.

Open http://localhost:4000 for usage instructions, or http://localhost:9400 for the Local Dashboard. When deployed to Encore Cloud, use the Service Catalog to call endpoints and view traces to see how requests flow between services.

Signature Validation

When secrets are configured, incoming webhooks are verified using the official SDKs:

• Stripe — Uses the Stripe Node SDK (stripe.webhooks.constructEvent) to verify the Stripe-Signature header. Stripe signs payloads using a timestamp and HMAC-SHA256 signature in the format t=...,v1=....
• GitHub — Uses HMAC-SHA256 with crypto.timingSafeEqual to verify the X-Hub-Signature-256 header. GitHub signs payloads with HMAC-SHA256, prefixed with sha256=.

Without secrets configured, all webhooks are accepted without signature checks.

API Endpoints

Receive a webhook

# Stripe webhook (without signature validation)
curl -X POST http://localhost:4000/webhooks/stripe \
  -H "Content-Type: application/json" \
  -d '{"type": "payment_intent.succeeded", "data": {"object": {"amount": 2000}}}'

# GitHub webhook (without signature validation)
curl -X POST http://localhost:4000/webhooks/github \
  -H "Content-Type: application/json" \
  -H "X-GitHub-Event: push" \
  -d '{"ref": "refs/heads/main"}'

To test with signature validation, set the secrets and include the appropriate headers:

# GitHub with signature
SECRET="your-github-secret"
PAYLOAD='{"ref":"refs/heads/main"}'
SIG="sha256=$(echo -n "$PAYLOAD" | openssl dgst -sha256 -hmac "$SECRET" | awk '{print $2}')"
curl -X POST http://localhost:4000/webhooks/github \
  -H "Content-Type: application/json" \
  -H "X-Hub-Signature-256: $SIG" \
  -H "X-GitHub-Event: push" \
  -d "$PAYLOAD"

For Stripe, use the Stripe CLI to forward and sign webhooks locally:

stripe listen --forward-to localhost:4000/webhooks/stripe
stripe trigger payment_intent.succeeded

List processed events

curl http://localhost:4000/webhooks/events

Get a specific event

curl http://localhost:4000/webhooks/events/1

List important notifications

curl http://localhost:4000/notifications

Get notification stats

curl http://localhost:4000/notifications/stats