Availability tests

1. Availability tests

Welcome back! So far we have covered key features of Azure Monitor and even explored Application Insights. Let's now take a look at Availability Tests!

2. Is my app up?

We've all done this, refreshing a website again and again to see if it’s working. But in cloud systems, waiting for customers to report outages is too late. You need a way to know your app is down before they do.

3. Availability tests

Availability tests in Application Insights act like a heartbeat monitor for your application. They check your app at regular intervals, potentially from different locations around the world, and alert you if something isn’t responding correctly.

4. What are availability tests

Availability tests are synthetic checks that simulate user requests to your app. They run automatically on a scheduled basis to check website or API health, verify responses, and alert you if the app is slow, broken, or unavailable. Think of them as synthetic users testing your app constantly and ensuring your users do not experience problems.

5. The cost of finding out too late

Imagine this: it's Saturday night, and your e-commerce site goes down. Your on-call engineer is asleep. Customers try to place orders, get error pages, and leave. By morning, you've lost thousands in revenue and damaged customer trust.

6. The cost of finding out too late

The worst part? Your servers looked healthy. CPU was fine. Memory was fine. But a mis-configured load balancer was dropping requests silently. Nobody knew until Monday when support tickets piled up.

7. The cost of finding out too late

This is why availability tests exist. They continuously probe your application from multiple locations worldwide, alerting you the moment something fails. Instead of customers discovering outages, you discover them first.

8. Types of availability tests

Azure gives you multiple test types. Ping tests are quick and lightweight. Standard tests run in a real browser and validate complex interactions. Code-based tests give developers full control over custom checks.

9. Ping test

A ping test sends an HTTP GET request to your site. You choose the URL, how often to test, and from which Azure locations. It's ideal for checking basic uptime and response codes for example 200 meaning OK or 404 meaning failure.

10. Standard test

Standard tests, sometimes called browser tests run your app in a real browser. These are great for ensuring entire user journeys work. It can consist of loading dashboards, signing in, loading a page or checking a cart. They catch issues plain HTTP checks might miss.

11. Custom track test

Custom tests let developers write their own logic using the Application Insights SDK. For example, you can test an API workflow, validate a database response, or run multi-step business logic all from code.

12. Test results and insights

Availability tests generate rich data. You can view graphs showing uptime percentage, performance trends, and detailed test run results. If a test fails, you can drill into the logs to see what happened, such as a timeout, network error, or unexpected response. Over time, these insights help you detect patterns, like recurring slowdowns or intermittent failures tied to specific locations or deployment times.

13. Best practices

To get the most value from availability tests, run tests from multiple regions to catch location-specific issues. Choose test frequencies that balance coverage with cost. Validate critical user journeys, not just your homepage. Connect tests to alert rules so failures notify your team immediately. Review results regularly to spot patterns. Recurring slowdowns at specific times might indicate scheduled jobs competing for resources.

14. Let's practice!

Let's jump in and explore Availability Tests!

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