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You can move a Spring Boot application to Quarkus in either of two ways: keep supported Spring programming patterns with Quarkus compatibility extensions, or refactor toward Quarkus-native APIs such as Jakarta REST, CDI, and Panache. Compatibility can reduce early code changes; native APIs demand more refactoring but give the service a clearer Quarkus model. You can migrate incrementally rather than switching an entire application at once.
Choose a migration destination
Quarkus documents both native APIs and Spring compatibility extensions as valid targets. The right first step depends on whether the immediate priority is reducing code churn or aligning the service with Quarkus conventions. A team can also mix the approaches rather than making one choice for every feature.
| Decision axis | Spring compatibility extensions | Quarkus-native APIs |
|---|---|---|
| Initial code churn | Usually lower where the Spring feature is supported; familiar annotations and patterns can remain. | Higher when endpoints, injection, or data access need to be rewritten. |
| Unsupported-feature coverage | Partial by design. Compatibility does not mean that every Spring or Spring Boot feature is available. | Not applicable as Spring feature coverage: replace the feature with a Quarkus API or another supported extension and validate its behavior. |
| Long-term Quarkus alignment | Retains Spring-oriented patterns where supported. | Uses Quarkus’s own APIs and programming model. |
| Team learning cost | Can make an initial move easier for a Spring-focused team, though Quarkus build and runtime behavior still need learning. | Requires the team to learn and apply the relevant Quarkus APIs. |
| Automation repeatability | OpenRewrite can help apply repeatable dependency, annotation, configuration, and build edits; supported coverage still needs checking. | OpenRewrite can help with mechanical transformations, but API choices and application-specific behavior require review. |
| Native-image readiness | Not established by choosing compatibility alone; assess the actual application and extensions. | Not guaranteed by choosing native APIs; assess the actual application and extensions. |
| Operational risk | Requires validation of unsupported Spring behavior and differences in build, runtime, and deployment. | Requires validation of refactored behavior, build, runtime, and deployment. |
When compatibility is a useful first milestone
Choose compatibility when preserving familiar code is important to getting an initial service migration underway. Quarkus lists extensions covering Spring Web, Spring DI, Spring Data JPA, Spring Data REST, Spring Security, Spring Cache, Spring Boot properties, Spring Scheduled, and Spring Cloud Config. That list describes extension areas, not a guarantee that every Spring feature or behavior within them is supported.
When native APIs are the better destination
Prefer native APIs for a new or long-lived service when the team is ready to refactor and wants to work directly with Quarkus’s programming model. Quarkus’s guidance encourages Jakarta REST for new endpoint definitions. Native APIs can also make the intended Quarkus design more explicit, but they do not remove the need to test application behavior or deployment requirements.
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Check prerequisites and analyzer limits
The Snowdrop migration guide covers the Spring Boot 3.x to Quarkus 3.x path. It states that Quarkus 3.x requires Java 17 or later and lists Apache Maven 3.9.x. These are requirements and tooling details for that documented path; confirm the requirements for the specific Quarkus release you select before changing the build.
- The Snowdrop analyzer supports Maven only.
- It cannot migrate Maven multi-module projects.
- Quarkus extension support and configuration keys are version-sensitive, so select a target Quarkus version before applying build or configuration changes.
If the application is a Maven multi-module project, the analyzer constraint does not make migration impossible; it means that tool cannot migrate that project in its current form. Plan a different assessment or transformation approach and account for module boundaries in your own review.
Map Spring features deliberately
Annotation names can suggest a mapping, but they do not prove that lifecycle, transactions, validation, security, serialization, or testing semantics are identical. Choose the replacement feature by feature and verify the behavior that matters to the application.
| Spring pattern | Possible Quarkus direction | What to verify |
|---|---|---|
@RequestMapping and Spring Web endpoints |
Jakarta REST, using @Path; alternatively, a supported Spring Web compatibility extension. |
Route matching, request and response handling, validation, serialization, and security integration. |
@Autowired and Spring dependency injection |
CDI injection with @Inject, or supported Spring DI compatibility. |
Bean discovery, scopes, lifecycle, qualifiers, and startup behavior. |
Spring Data repositories such as JpaRepository |
Quarkus Panache or supported Spring Data compatibility. | Query behavior, transactions, persistence configuration, and test coverage. |
| Spring Security, caching, scheduling, properties, or Cloud Config | Use the relevant Quarkus extension or a supported compatibility extension where available. | Do not assume configuration keys, policy behavior, scheduling semantics, or integration details carry over unchanged. |
The Spring Web compatibility guide supports familiar Spring Web annotations while encouraging Jakarta REST for new endpoint definitions. The Spring DI compatibility guide documents the compatibility layer and warns that some Spring Boot test features are not supported by Quarkus. Treat tests that rely on those features as migration work, not as proof that the production code is incompatible.
Update the Maven build in a controlled sequence
For the documented Spring Boot 3.x to Quarkus 3.x migration, Snowdrop gives this representative Maven sequence. It is a starting template, not a drop-in replacement for every project’s build.
- Remove the Spring Boot parent from
pom.xml. - Import the Quarkus BOM under dependency management.
- Set
quarkus.platform.versionto the selected Quarkus platform version. - Align compiler source and target with Java 17 or later where required by the target version.
- Remove
spring-boot-maven-plugin. - Add
quarkus-maven-pluginand configure its build, code-generation, and test-code-generation goals.
After the structural changes, reconcile the complete build: dependencies, plugins, profiles, tests, and deployment target. Do not copy an old Quarkus plugin or extension configuration without checking it against the selected release.
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Use assessment and automation for the work they can repeat
Konveyor’s Migration Toolkit for Applications (MTA) is presented as a rule-based option for estimating migration effort across a portfolio and generating an assessment report. OpenRewrite’s SpringBootToQuarkus recipe targets repeatable dependency, annotation, configuration, and build changes. Its Quarkus recipe catalog also includes transformations for adding Spring compatibility extensions, replacing Spring Boot Actuator with Quarkus Health and Metrics, mapping the Spring Boot OAuth2 client to a Quarkus OIDC client, and replacing Spring Boot database drivers with Quarkus JDBC extensions.
- Assess first. Use MTA or equivalent rules to identify the technologies and features in scope, unsupported areas, and any analyzer constraints.
- Automate repeatable edits. Apply OpenRewrite recipes or equivalent transformations to mechanical build and source changes.
- Review and refactor. Check generated changes, resolve unsupported APIs, and make application-specific decisions manually.
Neither an assessment report nor a successful automated rewrite demonstrates that the migrated application behaves correctly. Treat the tools as ways to reduce repetitive work and expose issues earlier, not as substitutes for application testing and operational checks.
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- Freeze a tested branch. Inventory Spring starters, annotations, configuration keys, data access, security, messaging, scheduling, tests, and deployment assumptions.
- Select the target Quarkus release. Decide whether the first milestone prioritizes lower code churn or native Quarkus alignment.
- Run a migration assessment. Identify unsupported features and check whether tool constraints, including Maven multi-module support, apply.
- Apply repeatable transformations. Use OpenRewrite or an equivalent approach for mechanical build and source changes.
- Choose extensions and replacements feature by feature. Decide where compatibility is appropriate and where native APIs are a better fit.
- Compile early, then exercise unit, integration, contract, security, and startup behavior. Investigate failures at the point where they appear instead of assuming an annotation mapping preserved semantics.
- Measure startup, memory, throughput, native-image feasibility, and deployment behavior under your own workload. No performance or cost improvement should be assumed without those measurements.
- Roll out incrementally with observability and a rollback plan for each deployment step.
Migrate incrementally instead of waiting for a big-bang cutover
Quarkus states that teams can migrate one service at a time and use compatibility extensions and native APIs side by side, even class by class. That makes it possible to bound risk: keep a supported Spring pattern where replacing it would delay a service, while using a native API for a new or refactored component. Define the boundary, test interactions across it, and plan any remaining compatibility code as explicit follow-up work rather than assuming it will disappear automatically.
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