In the microservice field, end-to-end testing is not limited to requirement testing. Taking one step ahead, performance testing should be considered in this. As in a microservice architecture, every service runs on different machines and there is an endpoint in all the services that are called by other services. So, there would be a question as to whether load testing of these endpoints should be done on the component level in isolation or the application level.

If load/performance testing is done on the component level, then it will be very helpful to identify which service is performing slowly. In addition to that, different layers' issues, network layer issues, and machine level issues are also highlighted in this testing. This type of testing points out the bottlenecks of performance. It will also help to identify application strength in network latency, packet loss, and scaling policies of components. Performance testing becomes a challenge for testers. Any new release can cause slow performance at the UI level; then, identifying which microservice is slow becomes a challenge. At this level, monitoring plays an important role in the microservice architecture. We will learn about monitoring in Chapter 9, Monitoring and Scaling.