Okay, so you're a micro-services developer and, several years ago, you decided to adopt Spring in general, and Spring Boot/Cloud in particular, as a development platform. You're a Java fullstack developer, meaning that you're working on the back-end side, as well as on the front-end side.
In your previous projects, you have implemented back-end micro-servicves with Spring Boot and you decided to use its out-of-the-box support of the Oauth 2.0 protocol, for authorization purposes and for its RBAC (Role Based Access) features. You've found this support very usefull and practical, hence, you'd like to continue using it in your future projects.
Should this be your case, please continue reading as you might have heard that that the mentioned support got deprecated.
What does this mean, exactly ?
As a Java developer, even if you don't care much about deprecated features, you realize that it doesn't sound good. As a matter of fact, deprecation doesn't mean that you won't be able to continue using the given feature as long as you keep with the same release. As the Oracle Java SE documentation explains, deprecation means that the given class or package is not longer important. It is so unimportant that it's being superseeded by another class or package and, hence, you're not supposed to use it any more, as it will cease to exist in the future.
How bad is it ?
Of course, you may choose to continue using the deprecated artifact and to take on your IDE insistent warnings, which makes appear your code like a Christmass tree. To come back to our concern, which is Spring Security Oauth, if you're compiling against Spring Boot 2.2.7.RELEASE or older, nothing could prevent you to continue using Spring Security OAuth. But if you're like me, i.e. cautious about your code quality and, additionally, you want to be able to easily upgrade to future Spring Boot releases, then you need to address this issue ASAP.
It is worth noting however that the deprecation we're talking about here only concerns the OAuth providers of the Spring Security Oauth project, but not the consumers. The later are simply moved to Spring Security, as mentioned by the OAuth Migration Guide.
Since Spring Security doesn’t provide Authorization Server support, migrating a Spring Security OAuth Authorization Server is out of scope for this document.
So, what this means in clear is that, if you relay on OAuth service providers, as implemnted by Spring Security OAuth project, then don't do it anymore. Just manage yourself to find another solution. And don't come asking us how to do it 'cause this is out of our scope.
Governance, methodology and deontology
As everyone knows, Java is an open-source programming language and computing platform. Its real open-source nature is a long and complicated story but at least most of its compoenents are available under open-source licences.
The Java governance model is based on Java Community Process (JCP), a program which aims at standardizing its specification and development process. Things might have become a bit different in the last years, with the purchase of SunMicrosystems by Oracle but, in clear, it's the JCP who decides what a given JVM release will contain. It's also the JCP responsibility to provide specifications for all the Java sub-technologies like Servlet, EJB (Enterprise Java Beans), JMS (Java Messaging Service), CDI, (Context and Dependency Injection), JAX-WS (Java API for XML Services), JAX-RS (Java API for RESTful Web Services), JDBC (Java Data Base Connection), JPA (Java Persistance API), JTA (Java Transaction API), JAX-B (Java Architecture for XML Binding) and dozens of others. All these sub-technologies were included initially in Java EE (Enterprise Edition) and are currently owned by the Eclipse Foundation, under the name of Jakarta EE.
Spring, and all its sub-technologies like Spring Boot, Spring Cloud, Spring Security, etc., are open-source and Java as well but they obey to a different governance model. After a long and involved history, Spring finished by belonging to Pivotal, a private oragnization like Oracle. From this point of view there is no difference. But as opposed to Java that, before being owned by Oracle, used to have a very opened a democratic governance model based on community, Spring is driven by Pivotal in a quite unilateral manner.
As oposed to Java where everything is object of detailed specifications approved by the comunity through JCP, in the form of JSRs (Java Specification Requests), Spring doesn't even have any specification. Spring is a set of libraries providing the services, the APIs and the documentation that its owner decided to provide. And should this owner decide to stop providing some services, APIs or documentation then there is nothing you can do about.
This is exactly what happened with the Spring Security Oauth project. It has simply been decomissioned ! Okay, it seems that further to the users formal protests, Pivotal decided that the subject merits further examonation. But as per today, there is no final decision. Which, of course, results in deontological problems.
What everything is about ?
Spring Security Oauth project aimes at supplying OAuth 1(a) and OAuth 2.0 providers and consumers support. This is somehow not completely in line with the Spring general philosophy which consists in proposing SPIs (Software Provider Interface) to almost everything, but not the service providers themself.
As a matter of fact, if we take for example the transaction management, Spring is able to interface with your platform's transaction manager via delegates like
JtaTransactionManager, etc. But the transaction manager itself needs to be provided by the platform.
If we take for example LDAP or
ActiveDirectory, Spring is giving you all the required features such to interface with most of the implementations, but it doesn't provide an LDAP service.
There are dozens of other similar examples but the main idea is that Spring, all sub-technologies included, fulfills the rule "wraps everything, provides nothing". In this manner, deprecating the Spring Security OAuth project, removing the OAuth providers and migrating the consumers to Spring Security 5.2.x, might make sense.
What now ?
Okay, since Pivotal has retired the Spring Security Oauth project, leaving in a daze all the users and developers, another solution is needed. One of the most suitable one is Keycloak, an open-source IAM (Identity Access Management) solution maintained by Red Hat. Its commercial counterpart is Red Hat SSO Server.
There are several samples and tutorials demonstrating how to integrate Spring Boot micro-services with Keycloak but, if you want to see mine, please look here.