A Working Eclipse MicroProfile Code Sample

In this chapter, we will discuss a sample application that makes use of the various MicroProfile features introduced earlier in this book. The MicroProfile runtime we will use in this chapter is the Quarkus runtime, a Kubernetes-native Java stack tailored for GraalVM and OpenJDK HotSpot, crafted from best of breed Java libraries and standards. Key topics that we will cover include the following:

• Use of configuration for both application and MicroProfile container behaviors
• Realistic health checks
• Securing an application with an external JWT security provider
• Integrating and viewing trace information with a Jaeger instance
• Inspecting microservice endpoint information using Swagger
• Viewing individual and complete application metrics
• Accessing both intra-cloud and external microservices using the rest client

The purpose of these topics...

Technical requirements

For this chapter, we'll require the following:

• An IDE
• JDK 1.8+ installed with JAVA_HOME configured appropriately
• Apache Maven 3.5.3+
• A running Docker environment

The code for this chapter can be found at https://github.com/PacktPublishing/Hands-On-Enterprise-Java-Microservices-with-Eclipse-MicroProfile/tree/master/Chapter08-mpcodesample.

The sample in this chapter can be compiled into a native binary using the GraalVM (https://github.com/oracle/graal/releases/tag/vm-1.0.0-rc16) integration of Quarkus. This has additional requirements for the installation of the 1.0-RC16 version Graal VM and a working C development environment. The details of the native image generation requirements can be found at https://quarkus.io/guides/building-native-image-guide.

Sample architecture of a multiservice MicroProfile application

The sample application we will go over in this chapter is composed of an HTML frontend, two MicroProfile-based microservices, two external services we spin up using Docker, and an external time service on the web we have no control over. The architecture of our sample application is shown in the following diagram:

The key elements in this diagram include the following:

• Svcs1 Image: This is a collection of REST endpoints that make use of MP-HC, MP-Metrics, MP-OT, MP-JWT, MP-OAPI, MP-FT, and MP-RC in a Quarkus runtime.
• Svcs2 Image: This is a collection of REST endpoints that make use of MP-HC and MP-Metrics in a Quarkus runtime.
• Jaeger: This a Docker image that runs the Jaeger server for the collection of trace loggings.
• KeyCloak: This is a Docker image that runs a KeyCloak 6.0.0 server instance.
• WorldClock: This is...

Summary

This chapter has walked us through a sample service mesh composed of a web application, two microservice images using MP features in a new Quarkus implementation, an external web service, and two Docker-based services. This showed the interplay between the various MP features and external services you will find in cloud environments, along with integration with web services external to the local mesh environment. This should give you a feeling of the steps involved when composing microservices using the MicroProfile APIs and implementations.

In the next chapter, we will take a look at MicroProfile specifications that are under development to have an idea of what directions are being explored. While these specifications are currently outside of the MicroProfile core feature set, they are candidates for future inclusion, and looking at them will give us an idea of where...

Questions

1. Do the MP-Config settings affect application code, MP feature code, or both?
2. Were you able to update health.pathToMonitor to a valid path and see an updated health status reply?
3. What does the Svcs2 health status link (http://localhost:8082/health) on the Health tab show as its output? If you stop the KeyCloak Docker image and click on the link again, does the output change?
4. What happens if you select the MetricController.timed-request link (http://localhost:8080/metrics/application/io.packt.sample.metric.MetricController.timed-request) in the Metrics tab without first hitting the Timed endpoint link (http://localhost:8080/demo1/metric/timed) at least once?
5. Go to the RestClient tab and hit the link, making sure you have a valid JWT. Next, go to the OpenTracing tab and open the Jaeger UI, and pull up the current traces by clicking the Find Traces button. You should see...

Further reading

Going over the code, trying changes, and then interacting with the updated code is a good way to understand more of the details behind the sample services. The Quarkus MicroProfile implementation supports live reload features that allow you to make changes without having to rebuild. For more information on this topic, see Maven Tooling (https://quarkus.io/guides/maven-tooling.html) on the Quarkus site.