BlogFly.io Webhooks

How to Test Fly.io Webhooks

Fly.io machine and app webhooks notify your systems about deployment events, health checks, and machine state transitions.

Fly.io Official Webhook Docs

1. Fly.io Webhook Events

Fly.io can send the following webhook events to your endpoint:

machine.created
machine.started
machine.stopped
machine.destroyed
machine.updated

2. Set Up a Test Endpoint with HookRay

Follow these steps to start receiving Fly.io webhooks for testing:

  1. Go to HookRay and click "Start Testing — Free" to get your unique webhook URL.
  2. Copy the URL (e.g., https://h.hookray.com/abc123).
  3. In your Fly.io dashboard, navigate to the webhook settings and paste the HookRay URL as your endpoint.
  4. Select the events you want to receive (see list above).
  5. Trigger a test event — HookRay will show the incoming webhook in real-time.

3. Sample Fly.io Webhook Payload

Here's an example of what a Fly.io webhook payload looks like:

payload.json
{
  "type": "machine.started",
  "app": "hookray-production",
  "machine": {
    "id": "e784079b449483",
    "name": "hookray-api-1",
    "state": "started",
    "region": "nrt",
    "image": "registry.fly.io/hookray:latest"
  },
  "timestamp": "2026-03-20T20:00:00.000Z"
}

4. Common Issues & Troubleshooting

Webhook not arriving?

Check that your endpoint URL is correct and publicly accessible. Fly.io cannot reach localhost URLs — use HookRay's cloud URL instead.

Getting 400 or 500 errors?

HookRay accepts any payload and returns 200 OK by default, so the issue is likely on Fly.io's side. Check your webhook configuration and event selection.

Need to verify webhook signatures?

Fly.io signs webhook requests for security. Use HookRay to capture the raw headers and body, then implement signature verification in your application code.

5. Next Steps

  • Use HookRay's webhook replay feature to re-send captured webhooks while building your handler
  • Enable smart parsing (Pro plan) to see Fly.io-specific fields highlighted automatically
  • Check the Fly.io webhook documentation for the complete event reference

Ready to test Fly.io webhooks?

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