Missing Spring Boot Starter Undertow 4.0.0 Release: Causes And Fixes

by Alex Johnson 69 views

Are you encountering a frustrating dependency error when upgrading to Spring Boot 4.0.0? You're not alone! Many developers have reported a missing spring-boot-starter-undertow release, leading to build failures. In this article, we'll dive deep into the cause of this issue, explore potential solutions, and guide you through workarounds to get your Spring Boot application up and running smoothly.

Understanding the Missing Release

The core of the problem lies in the absence of a stable 4.0.0 release for spring-boot-starter-undertow. While Spring Boot 4.0.0 has been released, its Undertow starter dependency seems to be stuck at the Milestone 1 (M1) version. This discrepancy causes build tools like Gradle to fail when they can't resolve the expected 4.0.0 artifact.

Why is Undertow Important? Undertow is a flexible and high-performance web server that can be used as an alternative to Tomcat in Spring Boot applications. By excluding the default Tomcat starter and including spring-boot-starter-undertow, developers can leverage Undertow's capabilities. However, the missing release disrupts this seamless integration.

The error message typically encountered looks like this:

Caused by: org.gradle.internal.resolve.ModuleVersionNotFoundException: Could not find org.springframework.boot:spring-boot-starter-undertow:4.0.0.

This message clearly indicates that the build system is unable to locate the 4.0.0 version of the Undertow starter.

How Does This Affect Your Build? If you're using a Gradle dependency snippet like this:

implementation('org.springframework.boot:spring-boot-starter-web') {
 exclude group:'org.springframework.boot', module:'spring-boot-starter-tomcat'
}
implementation 'org.springframework.boot:spring-boot-starter-undertow'

you're likely to encounter this issue when upgrading to Spring Boot 4.0.0. The exclude directive removes Tomcat, and the implementation line adds Undertow, but the missing release breaks the chain.

Diving Deeper into the Issue: Why No 4.0.0 Release?

It's essential to understand why this discrepancy exists. While the official reasons may vary, it's common for specific modules or starters within a larger framework like Spring Boot to have different release cycles. Sometimes, a particular component might require additional testing, bug fixes, or alignment with other dependencies before a stable release can be made.

Potential Reasons for the Delay:

  • Unresolved Bugs: There might be critical bugs or issues discovered during the 4.0.0 development cycle specifically related to the Undertow integration. These need to be addressed before a stable release can be made.
  • Dependency Conflicts: Undertow itself has dependencies, and there might be conflicts or compatibility issues with other libraries used in Spring Boot 4.0.0. Resolving these conflicts can take time.
  • Testing and Stabilization: Thorough testing is crucial for any software release. The Undertow starter might require additional testing to ensure stability and performance under various conditions.
  • Feature Development: It's also possible that new features or improvements are being implemented in the Undertow starter, delaying the release until these are complete and tested.

While the exact reason might not be publicly documented, understanding these possibilities helps manage expectations and explore potential workarounds.

Workarounds and Solutions for the Missing Release

Now, let's get to the practical part: how to address this missing release and get your Spring Boot application building successfully. Here are several workarounds and solutions you can consider:

1. Revert to a Stable Spring Boot Version

The simplest solution, if feasible, is to temporarily revert to a stable Spring Boot version where the spring-boot-starter-undertow release is available (e.g., a 3.x version). This will allow you to continue development without encountering the dependency error. Of course, this means you won't be able to leverage the new features and improvements in Spring Boot 4.0.0 just yet.

How to Revert:

In your build.gradle or pom.xml file, change the springBootVersion property or the Spring Boot starter dependencies to a stable 3.x version. For example:

ext {
 springBootVersion = '3.2.0'
}

dependencies {
 implementation('org.springframework.boot:spring-boot-starter-web') {
 exclude group:'org.springframework.boot', module:'spring-boot-starter-tomcat'
 }
 implementation 'org.springframework.boot:spring-boot-starter-undertow'
}

2. Use the Milestone Release (4.0.0-M1)

While not ideal for production environments, you can temporarily use the 4.0.0-M1 milestone release of spring-boot-starter-undertow. This will allow your build to succeed, but be aware that milestone releases might contain bugs or instability.

How to Use the Milestone Release:

In your build.gradle or pom.xml, explicitly specify the 4.0.0-M1 version for the Undertow starter:

dependencies {
 implementation('org.springframework.boot:spring-boot-starter-web') {
 exclude group:'org.springframework.boot', module:'spring-boot-starter-tomcat'
 }
 implementation 'org.springframework.boot:spring-boot-starter-undertow:4.0.0-M1'
}

Important Note: If you choose this option, be sure to monitor for updates and switch to the stable 4.0.0 release as soon as it becomes available.

3. Wait for the Stable 4.0.0 Release

The most recommended solution is to patiently wait for the official 4.0.0 release of spring-boot-starter-undertow. Keep an eye on the Spring Boot project's release notes, GitHub repository, and community forums for updates. This ensures you're using a stable and well-tested version of the starter.

How to Stay Updated:

  • Spring Boot Release Notes: Check the official Spring Boot release notes for announcements about new releases and updates.
  • GitHub Repository: Monitor the Spring Boot GitHub repository for activity and discussions related to the Undertow starter.
  • Community Forums: Participate in Spring Boot community forums and discussions to stay informed about the release status.

4. Explore Alternative Web Servers

If using Undertow isn't a strict requirement, you could consider sticking with the default Tomcat server or exploring other embedded web server options available in Spring Boot, such as Jetty. This might involve adjusting your configuration and dependencies, but it can be a viable workaround if you need to move forward with Spring Boot 4.0.0 immediately.

How to Use Tomcat (Default):

Simply remove the exclude directive for Tomcat and remove the spring-boot-starter-undertow dependency from your build.gradle or pom.xml.

dependencies {
 implementation('org.springframework.boot:spring-boot-starter-web')
}

How to Use Jetty:

  1. Exclude Tomcat:

    implementation('org.springframework.boot:spring-boot-starter-web') {
 exclude group:'org.springframework.boot', module:'spring-boot-starter-tomcat'
}

  2. Add the Jetty starter:

    implementation 'org.springframework.boot:spring-boot-starter-jetty'

5. Custom Dependency Resolution (Advanced)

For advanced users, it might be possible to manually resolve the Undertow dependencies and include them in your project. This involves carefully analyzing the Undertow requirements and adding the necessary libraries. However, this approach is complex and can lead to dependency conflicts if not handled correctly. Therefore, it's generally not recommended unless you have a deep understanding of dependency management.

Best Practices and Recommendations

While you're navigating this missing release issue, keep these best practices in mind:

  • Stay Informed: Regularly check for updates on the Spring Boot project and community forums.
  • Test Thoroughly: If you use a milestone release or a custom workaround, test your application thoroughly to ensure stability.
  • Document Your Solution: Clearly document the workaround you've implemented so that other developers (and your future self) understand the situation.
  • Contribute to the Community: If you encounter a bug or find a solution, consider sharing it with the Spring Boot community to help others.

Real-World Implications and Scenarios

Let's consider some real-world scenarios to illustrate the impact of this missing release:

  • New Projects: Developers starting new Spring Boot 4.0.0 projects who want to use Undertow will immediately encounter this issue.
  • Upgrading Existing Projects: Teams upgrading existing applications to Spring Boot 4.0.0 will need to address this dependency problem.
  • Microservices Architectures: In microservices environments where different services might use different web servers, this issue can cause inconsistencies.
  • Cloud Deployments: Cloud deployment pipelines that automatically build and deploy applications might fail due to the missing dependency.

These scenarios highlight the importance of having a clear understanding of the issue and available workarounds.

The Importance of Community and Open Source

The Spring Boot ecosystem thrives on community contributions and open-source collaboration. When issues like this arise, it's a great opportunity to engage with the community, share your experiences, and potentially contribute to the solution. Reporting the issue, providing feedback, and even submitting pull requests can help improve the framework for everyone.

Conclusion

The missing 4.0.0 release for spring-boot-starter-undertow is a temporary setback in the Spring Boot 4.0.0 journey. While it can be frustrating, understanding the cause and exploring the workarounds discussed in this article will help you navigate the issue effectively. Remember to stay informed, test thoroughly, and engage with the Spring Boot community. By working together, we can ensure a smooth transition to the latest Spring Boot features and improvements.

Stay tuned for updates and the official 4.0.0 release! In the meantime, you can learn more about Spring Boot and its modules on the official Spring Boot website.