MicroProfile Health Check and JWT Propagation

In this chapter, we will introduce the MicroProfile Health Check and JSON Web Token (JWT) Propagation projects. The Health Check project is concerned with exposing the application-defined health to the outside world, and JWT Propagation is concerned with defining an interoperable security token and use of that token in an application. In this chapter, you will learn the concerns that these specifications address, their constructs, and how to use them in your application. The code snippets throughout this chapter are for reference only. If you would like a working code version of this specification, please refer to Chapter 8, A Working Eclipse MicroProfile Code Sample.

We will cover the following topics:

• What a health check is
• How MicroProfile Health Check exposes the health check endpoint and the format of a query to that endpoint...

Technical requirements

To build and run the samples in this chapter, you need Maven 3.5+ and a Java 8 JDK. The code for this chapter can be found at https://github.com/PacktPublishing/Hands-On-Enterprise-Java-Microservices-with-Eclipse-MicroProfile/tree/master/Chapter04-healthcheck and https://github.com/PacktPublishing/Hands-On-Enterprise-Java-Microservices-with-Eclipse-MicroProfile/tree/master/Chapter04-jwtpropagation for the MicroProfile Health Check and MicroProfile Propagation JWT sections, respectively.

Understanding health checks and how MicroProfile handles them

In cloud-native architectures, health checks are used to determine whether a computing node is alive and ready to perform work. The concept of readiness describes the state when containers start up or roll over (that is, redeployment). During this time, the cloud platform needs to ensure that no network traffic is routed to that instance before it is ready to perform work.

Liveness, on the other hand, describes the state of a running container; that is, can it still respond to requests? If either the liveness or readiness states are seen as invalid, the computing node will be discarded (terminated or shut down) and eventually replaced by another, healthy, instance.

Health checks are an essential contract with the orchestration framework and scheduler of the cloud platform. The check procedures are provided by the application...

Using JSON Web Token Propagation in MicroProfile

A JSON Web Token (JWT) is a common format for carrying security information that is used by many different web-based security protocols. However, there is a lack of standardization around exactly what the contents of the JWT are and what security algorithms are used with signed JWTs. The MicroProfile JWT (MP-JWT) Propagation project specification looked at the OpenID Connect (OIDC)-based (http://openid.net/connect/) JWT (https://tools.ietf.org/html/rfc7519) specifications and built upon those to define a set of requirements to promote interoperability of JWTs for use in MicroProfile-based microservices, along with APIs to access information from the JWTs.

For a description of how OIDC and JWT work, including how an application/microservice intercepts bearer tokens, please refer to the Basic Client Implementer's Guide at http...

Summary

In this chapter, we learned about the MicroProfile Health Check and JWT Propagation projects. You should now understand what a health check is and how to add application-specific checks, known as procedures. These allow your microservice to describe its non-trivial health requirements in a cloud environment. You should also understand how JWTs can be used to provide an authentication and authorization capability on top of your microservices to control access to your endpoints. You should also understand how content from the JWT can be used to augment your microservice in user-specific ways.

The next chapter will introduce the MicroProfile Metrics and OpenTracing features. These allow your microservices to provide additional information regarding common and application metrics and to trace the interactions between microservices.

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Questions

1. Is the MP-HC wire format useful in all environments?
2. Can an MP-HC response contain arbitrary properties?
3. What if my application has different types of services that need to report health status?
4. What is a JWT?
5. What is a claim?
6. Are there restrictions on what can be in a JWT?
7. What is/are the main step(s) in authenticating a JWT?
8. Beyond the security annotations, how might we perform an authorization check using JWTs?