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Buildkite Webhooks

TL;DR

To integrate Buildkite webhooks with ngrok:

  1. Launch your local webhook. npm start
  2. Launch ngrok. ngrok http 3000
  3. Configure Buildkite webhooks with your ngrok URL.
  4. Secure your webhook requests with verification.

This guide covers how to use ngrok to integrate your localhost app with Buildkite by using Webhooks. Buildkite webhooks can be used to notify an external application whenever specific events occur in your Buildkite account.

By integrating ngrok with Buildkite, you can:

  • Develop and test Buildkite webhooks locally, eliminating the time in deploying your development code to a public environment and setting it up in HTTPS.
  • Inspect and troubleshoot requests from Buildkite in real-time via the inspection UI and API.
  • Modify and Replay Buildkite Webhook requests with a single click and without spending time reproducing events manually in your Buildkite account.
  • Secure your app with Buildkite validation provided by ngrok. Invalid requests are blocked by ngrok before reaching your app.

Step 1: Start your app​

For this tutorial, we'll use the sample NodeJS app available on GitHub.

To install this sample, run the following commands in a terminal:

git clone https://github.com/ngrok/ngrok-webhook-nodejs-sample.git
cd ngrok-webhook-nodejs-sample
npm install

This will get the project installed locally.

Now you can launch the app by running the following command:

npm start

The app runs by default on port 3000.

You can validate that the app is up and running by visiting http://localhost:3000. The application logs request headers and body in the terminal and responds with a message in the browser.

Step 2: Launch ngrok​

Once your app is running successfully on localhost, let's get it on the internet securely using ngrok!

  1. If you're not an ngrok user yet, just sign up for ngrok for free.

  2. Download the ngrok agent.

  3. Go to the ngrok dashboard and copy your Authtoken.
    Tip: The ngrok agent uses the auth token to log into your account when you start a tunnel.

  4. Start ngrok by running the following command:

    ngrok http 3000

  5. ngrok will display a URL where your localhost application is exposed to the internet (copy this URL for use with Buildkite). ngrok agent running

Step 3: Integrate Buildkite​

To register a webhook on your Buildkite account follow the instructions below:

  1. Access Buildkite and sign in using your Buildkite account.

  2. On the welcome page, click Settings on the top menu and click Notification Services on the left menu.

  3. On the Notification Services page, click Add for the Webhook line.

  4. On the Add Webhook Notification page, enter My LocalHost App in the Description field and enter the URL provided by the ngrok agent to expose your application to the internet in the Webhook URL field (i.e. https://1a2b-3c4d-5e6f-7g8h-9i0j.sa.ngrok.io). Webhook URL

  5. In the Events section, select all events.

  6. In the Pipelines section, select All Pipelines, and then click Add Webhook Notification.

Run Webhooks with Buildkite and ngrok​

Buildkite sends different request body contents depending on the event that is being triggered. You can trigger new calls from Buildkite to your application by following the instructions below.

  1. On the welcome page, click Pipelines on the top menu and then click one of your pipelines. Note: Create a pipeline if you don't have one by clicking Create your first pipeline and following the instructions on the screen.

  2. On your pipeline page, click New Build, enter a message in the Message field, and then click Create Build.

    Confirm your localhost app receives event notifications and logs both headers and body in the terminal.

Alternatively, you can verify the log of the webhook call in Buildkite:

  1. Click Settings on the top menu, click Notification Services on the left menu, click the My LocalHost App webhook tile, scroll down to the Request Log section, and then click one of the logs: Webhook Logs

Inspecting requests​

When you launch the ngrok agent on your local machine, you can see two links:

  • The URL to your app (it ends with ngrok-free.app for free accounts or ngrok.app for paid accounts when not using custom domains)
  • A local URL for the Web Interface (a.k.a Request Inspector).

The Request Inspector shows all the requests made through your ngrok tunnel to your localhost app. When you click on a request, you can see details of both the request and the response.

Seeing requests is an excellent way of validating the data sent to and retrieved by your app via the ngrok tunnel. That alone can save you some time dissecting and logging HTTP request and response headers, methods, bodies, and response codes within your app just to confirm you are getting what you expect.

To inspect Buildkite's webhooks call, launch the ngrok web interface (i.e. http://127.0.0.1:4040), and then click one of the requests sent by Buildkite.

From the results, review the response body, header, and other details:

ngrok Request Inspector

Replaying requests​

The ngrok Request Inspector provides a replay function that you can use to test your code without the need to trigger new events from Buildkite. To replay a request:

  1. In the ngrok inspection interface (i.e. http://localhost:4040), select a request from Buildkite.

  2. Click Replay to execute the same request to your application or select Replay with modifications to modify the content of the original request before sending the request.

  3. If you choose to Replay with modifications, you can modify any content from the original request. For example, you can modify the id field inside the body of the request.

  4. Click Replay.

Verify that your local application receives the request and logs the corresponding information to the terminal.

Secure webhook requests​

The ngrok signature webhook verification feature allows ngrok to assert that requests from your Buildkite webhook are the only traffic allowed to make calls to your localhost app.

Note: This ngrok feature is limited to 500 validations per month on free ngrok accounts. For unlimited, upgrade to Pro or Enterprise.

This is a quick step to add extra protection to your application.

  1. Access Buildkite and sign in using your Buildkite account.

  2. On the organization page, click Settings on the top menu and click Notification Services on the left menu.

  3. On the Notification Services page, click the My LocalHost App webhook tile, copy the value of the Token field, select Send an HMAC signature, and then click Save Webhook Settings.

  4. Restart your ngrok agent by running the command, replacing {your token} with the value you have copied before:

    ngrok http 3000 --verify-webhook buildkite --verify-webhook-secret {your token}

  5. Click Pipelines on the top menu, select one of your pipelines and create a new build.

Verify that your local application receives the request and logs information to the terminal.