February 23, 2021 in Only Happened In India, Php, Technology, Tips and Tricks
Testing Webhooks Locally for Amazon SNS
Testing Tools
To test the code I wrote for the blog post, I used PHP’s built-in web server (available in PHP 5.4 and later) to serve the code locally. I used another tool called ngrok to expose the locally running PHP server to the public internet. Ngrok does this by creating a tunnel to a specified port on your local machine.
You can use PHP’s built-in web server and ngrok on Windows, Linux, and Mac OS X. If you have PHP 5.4+ installed, then the built-in server is ready to use. To install ngrok, use the simple instructions on the ngrok website. I work primarily in OS X, so you may need to modify the commands I use in the rest of this post if you are using another platform.
Setting Up the PHP Code
First, you’ll need the PHP code that will handle the incoming messages. My post about receiving SNS messages provides a complete code example for doing this.
Let’s create a new folder in your home directly to use for this test. We’ll also install Composer, the AWS SDK for PHP, create a directory for the webroot, and create files for the PHP code and a log.
mkdir ~/sns-message-test && cd ~/sns-message-test curl -sS https://getcomposer.org/installer | php php composer.phar require aws/aws-sdk-php:~2.6.0 touch messages.log mkdir web && touch web/index.php
Now take the PHP code from the other blog post and put it in index.php. Here is that same code, but with the require statement needed to load the SDK with our current file structure. I am also going to update the code to log the incoming messages to a file so we can easily see that the messages are being handled correctly.
<?php
require __DIR__ . '/../vendor/autoload.php';
use AwsSnsMessageValidatorMessage;
use AwsSnsMessageValidatorMessageValidator;
use GuzzleHttpClient;
// Make sure the request is POST
if ($_SERVER['REQUEST_METHOD'] !== 'POST') {
http_response_code(405);
die;
}
try {
// Create a message from the post data and validate its signature
$message = Message::fromRawPostData();
$validator = new MessageValidator();
$validator->validate($message);
} catch (Exception $e) {
// Pretend we're not here if the message is invalid
http_response_code(404);
die;
}
if ($message->get('Type') === 'SubscriptionConfirmation') {
// Send a request to the SubscribeURL to complete subscription
(new Client)->get($message->get('SubscribeURL'))->send();
}
// Log the message
$file = new SplFileObject(__DIR__ . '/../messages.log', 'a');
$file->fwrite($message->get('Type') . ': ' . $message->get('Message') . "n");
Creating an Amazon SNS Topic
Before you can perform any tests, you must set up an Amazon SNS topic. You can do this easily in the AWS Management Console by following the Getting Started with Amazon Simple Notification Service guide. This guide also shows how to subscribe to a topic and publish a message, which you will also need to do in a moment.
Setting Up the Server
OK, we have an Amazon SNS topic ready and all of the files we need in place. Now we need to start up the server and make it accessible to Amazon SNS. To do this, create 3 separate terminal windows or tabs, which we will use for 3 separate long-running processes: the server, ngrok, and tailing the messages log.
Launching the PHP Built-in Server
In the first terminal window, use the following command to start up the PHP built-in web server to serve our little test webhook. (Note: you can use a different port number, just make sure you use the same one with ngrok.)
php -S 127.0.0.1:8000 -t web/
This will create some output that looks something like the following:
PHP 5.4.24 Development Server started at Mon Mar 31 11:02:14 2014 Listening on http://127.0.0.1:8000 Document root is /Users/your-user/sns-message-test/web Press Ctrl-C to quit.
If you access http://127.0.0.1:8000 from your web browser, you will likely see a blank page, but that request will show up in this terminal window. Since our code is set up to respond only to POST requests, we will see the expected behavior of a 405 HTTP code in the response.
[Mon Mar 31 11:02:44 2014] 127.0.0.1:61409 [405]: /
Creating a Tunnel with ngrok
In the second terminal window, use the following command to create an ngrok tunnel to the PHP server. Use the same port as you did in the previous section.
ngrok 8000
That was easy! The output of this command will contain a publicly accessible URL that forwards to your localhost.
Tunnel Status online Version 1.6/1.5 Forwarding http://58565ed9.ngrok.com -> 127.0.0.1:8000 Forwarding https://58565ed9.ngrok.com -> 127.0.0.1:8000 Web Interface 127.0.0.1:4040 # Conn 1 Avg Conn Time 36.06ms
ngrok also provides a small web app running on localhost:4040 that displays all of the incoming requests through the tunnel. It also allows you to click a button to replay a request, which is really helpful for testing and debugging your webhooks.
Tailing the Message Logs
Let’s use the third terminal window to tail the log file that our PHP code writes the incoming messages to.
tail -f messages.log
This won’t show anything yet, but once we start publishing Amazon SNS messages to our topic, they should be printed out in this window.
Testing the Incoming SNS Messages
Now that everything is running and wired up, head back to the Amazon SNS console and subscribe the URL provided by ngrok as an HTTP endpoint for your SNS topic.
If all goes well, you should see output similar to the following on each of the 3 terminal windows.
PHP Server:
[Tue Apr 1 08:51:13 2014] 127.0.0.1:50190 [200]: /
ngrok:
POST / 200 OK
Log:
SubscriptionConfirmation: You have chosen to subscribe to the topic arn:aws:sns:us-west-2:01234567890:sdk-test. To confirm the subscription, visit the SubscribeURL included in this message.
Back in the SNS console, you should see that the subscription has been confirmed. Next, publish a message to the topic to test that normal messages are processed correctly. The output should be similar:
PHP Server:
[Tue Apr 1 10:08:14 2014] 127.0.0.1:51235 [200]: /
ngrok:
POST / 200 OK
Log:
Notification: THIS IS MY TEST MESSAGE!
Nice work!
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