CI Jobs Not Working: OpenFeign Compilation Issues with Spring Boot 2.5.3 After September 29, 2024

Unexpected Compilation Issues with Spring Boot 2.5.3 in CI Environments

Starting from September 29, 2024, developers using Spring Boot 2.5.3 have reported facing unexpected compilation errors. Notably, these errors occur despite no changes in the codebase, causing considerable disruption in Continuous Integration (CI) workflows. This issue seems to be linked to the dependency resolution within Maven builds, particularly affecting projects using Spring Cloud dependencies.

The problem manifests as Maven builds failing with errors indicating missing dependencies. Specifically, the package org.springframework.cloud.openfeign is flagged as non-existent. This points to an issue with the OpenFeign dependency, causing errors like "cannot find symbol" and referencing missing classes like FeignClient.

For developers facing this situation, traditional debugging methods such as generating dependency trees or forcing Maven to go offline haven’t been effective. This scenario suggests a deeper issue possibly related to dependency updates or changes in the repositories.

In this article, we will explore the nature of these compilation errors, potential causes, and provide some troubleshooting steps to help you regain control over your Maven builds.

Analyzing and Resolving Spring Boot Compilation Issues in Maven

The scripts provided earlier focus on addressing a critical issue where Maven builds start failing with compilation errors in Spring Boot applications after September 29, 2024. These errors are centered around the missing OpenFeign dependency, causing the class FeignClient to become unavailable. The primary approach involves identifying and resolving these missing dependencies through specific Maven commands. For instance, the command `mvn dependency:tree -Dverbose` allows developers to visualize the entire dependency hierarchy in detail. This is crucial because it highlights transitive dependencies that might be missing or incorrectly resolved, leading to the observed error.

Another key command, `mvn dependency:go-offline`, enables a dependency resolution process in offline mode. This is particularly useful for determining if an external repository is the cause of the issue. In CI environments, network-related problems or changes in external repositories could result in inconsistencies in the resolution of dependencies like Spring Cloud OpenFeign. Running Maven in offline mode helps validate whether the issue stems from missing or corrupted artifacts in the local cache.

Further, the solution involves specifying a custom local repository for the Maven build using the command `mvn clean package -Dmaven.repo.local=./custom-m2`. This approach effectively isolates the default Maven repository by pointing Maven to a fresh, empty directory, forcing it to re-download all necessary dependencies. This helps to rule out any local caching issues that might lead to a corrupted or outdated dependency version. Additionally, manually clearing specific packages from the local repository, like `org/springframework/cloud/openfeign`, ensures that Maven downloads a fresh version of these artifacts.

Finally, to ensure the resolution of the problem, it is essential to conduct unit tests. The script provided earlier introduces test cases using JUnit to verify the configuration of Feign clients. These tests use the Spring Boot test framework to load the application context and perform checks on the presence and configuration of beans, such as Feign clients. Assertions like `assertNotNull` and `assertEquals` help verify that beans are correctly initialized and configured with the expected properties. By implementing these tests, developers gain a mechanism to validate that the issue has been resolved and that the Feign client configurations are correctly applied in the project.

# Step 1: Generate a fresh dependency tree to inspect possible issues
mvn dependency:tree -Dverbose > dependency-tree.log

# Step 2: Run Maven in offline mode to identify missing or outdated artifacts
mvn dependency:go-offline > dependency-offline.log

# Step 3: Clear your local Maven repository (optional, ensures a clean state)
rm -rf ~/.m2/repository/org/springframework/cloud/openfeign

# Step 4: Rebuild the project with debug information and custom local repository
mvn clean package -Dmaven.repo.local=./custom-m2 -DskipTests -X > build-debug.log

# Step 5: Review the generated logs for errors and fix any missing dependencies

# Step 1: Create or update a custom settings.xml file in your Maven configuration directory
<settings xmlns="http://maven.apache.org/SETTINGS/1.0.0">
  <mirrors>
    <mirror>
      <id>custom-mirror</id>
      <url>https://repo.spring.io/milestone/</url>
      <mirrorOf>central</mirrorOf>
    </mirror>
  </mirrors>
</settings>

# Step 2: Specify the custom settings file during the Maven build
mvn clean install -s ./settings.xml -DskipTests

# Step 3: Validate if the dependency resolution issue is fixed

@RunWith(SpringRunner.class)
@SpringBootTest
public class FeignClientTest {

  @Autowired
  private ApplicationContext context;

  @Test
  public void testFeignClientBeanExists() {
    Object feignClient = context.getBean("feignClientName");
    assertNotNull(feignClient);
  }

  @Test
  public void testFeignClientConfiguration() {
    FeignClient client = (FeignClient) context.getBean("feignClientName");
    // Add relevant assertions for configurations
    assertEquals("https://api.example.com", client.getUrl());
  }

}

Addressing Dependency Conflicts and Updates in Maven Projects

One key aspect that may contribute to Maven build failures in Spring Boot applications is dependency conflicts. These conflicts often arise due to overlapping versions or incompatible updates to core Spring Boot dependencies, such as OpenFeign or Spring Cloud libraries. Dependency conflicts can result in runtime errors, and in some cases, the absence of critical packages like org.springframework.cloud.openfeign. Addressing these conflicts typically requires a deep dive into the project’s dependency management, ensuring that there are no conflicting or outdated versions.

Developers may also face unexpected build issues when certain repositories or artifacts are altered without notice. Maven projects often rely on external repositories, which can change or deprecate specific versions, making previously available dependencies temporarily or permanently unavailable. Regularly reviewing the project’s dependency management configuration and locking dependency versions can mitigate such risks. Additionally, maintaining an updated internal repository or mirror can serve as a backup in case of outages or unexpected changes in external repositories.

Another essential aspect to consider is the use of comprehensive logging and debugging. When Maven builds fail, the error messages may not always provide complete information. Enabling debug logging through the `-X` flag allows developers to gather detailed insights into what’s happening behind the scenes. This practice can reveal issues related to missing dependencies, misconfigurations, or repository access problems. Incorporating systematic logging and debugging methods will help identify and isolate complex errors more effectively.