Sometimes, your infrastructure is all healthy except applications having an issue due to some bug in your code or any third-party software issues. You may have applied some vendor-provided operating system security patch that messed up your application. Application monitoring may include metrics, such as following:
- Endpoint invocation: Number of requests in a given period
- Response time: Average response time to fulfill the request
- Throttle: Number of valid requests spilled out as the system runs out of capacity to handle the additional requests
- Error: Application throws an error while responding to a request
The following screenshot shows a sample application endpoint-monitoring dashboard:
![](https://static.packt-cdn.com/products/9781838645649/graphics/assets/3b15b23b-5a2d-4dd8-ba2a-3f6bd323966e.png)
Application monitoring dashboard
There could be many more metrics based on application and technology—for example, a memory garbage collection amount for a Java application, a number of HTTP POST and GET requests for a RESTful service, a count of 4XX client errors,...