API & SDKs

Webhooks

Subscribe to deployment and health events with signature verification.

Relay delivers signed webhook events when deployments finish, quotas change, or origin health flips. Verify signatures before acting on payloads.

Event types

Event	When	Action
function.deployed	Deploy reaches ready	Invalidate caches
function.failed	Deploy rejected	Alert on-call
origin.unhealthy	Health check fails	Fail over
quota.warning	80% of limit used	Plan capacity

Verification sketch

tsverify.ts

const expected = hmacSha256(secret, rawBody);
if (!timingSafeEqual(expected, headerSignature)) {
  return new Response('invalid signature', { status: 401 });
}

Tip

Return 2xx quickly and process asynchronously. Slow webhook handlers are disconnected after 5 seconds.

Store the signing secret outside source control.
Reject timestamps older than five minutes.
Idempotently handle duplicate deliveries.

SDK examples

Observability