# Exercise #4¶

In this exercise we’re going to explore some of the things that we have created so far and how we can monitor them.

AWS X-Ray is a distributed tracing system. AWS X-Ray helps developers analyze and debug production, distributed applications, such as those built using a microservices architecture. With X-Ray, you can understand how your application and its underlying services are performing to identify and troubleshoot the root cause of performance issues and errors. We can use it to have a look at what is going on inside our new deployed setup. We can have a look at not only our Frontend application but trace all the way through to our Backend API within the same request.

Note

Many AWS services have automatic or simplified integrations with AWS X-Ray. For additional information about how to integrate and leverage the SDK, take a look at the documentation.

To start with, make sure you have a Tab in a browser opened with the Shop in it. If you can’t remember how to do that, pop back to Exercise #1 - Checklist for completion to find out how to load that from Step 4.

In another tab, open up the AWS X-Ray Console. You can do this by holding down ⌘ (CTRL on Windows) and clicking the link.

By default AWS X-Ray will show a Service Map from the last 5 minutes.

Click to expand sample AWS X-Ray Service Map Picture

On the left hand side, click Traces.

This will display a lot of information, but we can filter it down to show only what we care about. Let’s test this:

In the main search box, enter the following:

http.url ENDSWITH "baitcasting-reel/"


What this apply a filter to the search view to show only so traces where the URL ends in ‘baitcasting-reel’; so within the Shop browse Reels and then Baitcasting Reel.

Go back to the tab with AWS X-Ray in it and click refresh and you will see an item in the Trace List. Now click it and you’ll see the detail behind the trace.

You can see within the trace that not only does it show how long the page took to load, but also the SQL query. Let’s go a bit further and see what a call to the backend looks like.

Go back and replace the search box with:

http.url ENDSWITH "basket/ping"


Go to the shop tab and browse to /basket/ping by putting the URL in the browser directly. It should be https://<the domain>/basket/ping.

You should see a response that says: Artifishial Intelligence says: PONG.

Now go back to the X-Ray tab and tap refresh, you’ll see a trace and if you click into it you’ll see something like this:

What’s good here is that you can see the call through the API Gateway through to the Lambda function. If the Lambda function (our Backend service) was then to call services like Amazon RDS or Amazon DynamoDB, you would see that here.

This exercise scratches the surface of the kinds of tracing you can do with AWS X-Ray. You can find more information about X-Ray here.