Swagger SpringFox Parse Error

상세한 API documentation을 위해 swagger를 설정했다. 협업과 소통을 위해 pre-documentation에 쓸 수 있었지만 그때는 notion으로 API를 정리하기로 해서 기능 구현이 마무리된 지금 시점에 도입했다.

 

Spring Boot와 연동하는데, 버젼에 따라 configuration에 차이가 있고 조금 까다롭다.

implementation 'io.springfox:springfox-boot-starter:3.0.0'
implementation 'io.springfox:springfox-swagger-ui:3.0.0'

일단 이걸 추가해주는데, Spring Boot에 Swagger를 integrate하는데 여러 옵션이 있는데, springfox가 개중 하나다.

이후 Docket bean을 만들어줘야 되는데, Baeldung에서 가져온 공식문서이다. 스프링 부트 버젼에 따라 configuration 차이가 생기는 부분인데, 지금 프로젝트에 쓰고 있는 2.7.x 버젼에서 다음과 같은 에러가 비슷하게 뜬다.

00:50:54.956 [main] ERROR SpringApplication[reportFailure:830] - Application run failed
org.springframework.context.ApplicationContextException: Failed to start bean 'documentationPluginsBootstrapper'; nested exception is java.lang.NullPointerException: Cannot invoke "org.springframework.web.servlet.mvc.condition.PatternsRequestCondition.getPatterns()" because "this.condition" is null
    at org.springframework.context.support.DefaultLifecycleProcessor.doStart(DefaultLifecycleProcessor.java:181)
    at org.springframework.context.support.DefaultLifecycleProcessor.access$200(DefaultLifecycleProcessor.java:54)
    at org.springframework.context.support.DefaultLifecycleProcessor$LifecycleGroup.start(DefaultLifecycleProcessor.java:356)
    at java.base/java.lang.Iterable.forEach(Iterable.java:75)
    at org.springframework.context.support.DefaultLifecycleProcessor.startBeans(DefaultLifecycleProcessor.java:155)
    at org.springframework.context.support.DefaultLifecycleProcessor.onRefresh(DefaultLifecycleProcessor.java:123)
    at org.springframework.context.support.AbstractApplicationContext.finishRefresh(AbstractApplicationContext.java:935)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:586)
    at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:145)
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:740)
    at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:415)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:303)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1312)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1301)
    at com.atlas.psp.AtlasRouterApplication.main(AtlasRouterApplication.java:53)
Caused by: java.lang.NullPointerException: Cannot invoke "org.springframework.web.servlet.mvc.condition.PatternsRequestCondition.getPatterns()" because "this.condition" is null
    at springfox.documentation.spring.web.WebMvcPatternsRequestConditionWrapper.getPatterns(WebMvcPatternsRequestConditionWrapper.java:56)
    at springfox.documentation.RequestHandler.sortedPaths(RequestHandler.java:113)
    at springfox.documentation.spi.service.contexts.Orderings.lambda$byPatternsCondition$3(Orderings.java:89)
    at java.base/java.util.Comparator.lambda$comparing$77a9974f$1(Comparator.java:473)
    at java.base/java.util.TimSort.countRunAndMakeAscending(TimSort.java:355)
    at java.base/java.util.TimSort.sort(TimSort.java:234)
    at java.base/java.util.Arrays.sort(Arrays.java:1307)
    at java.base/java.util.ArrayList.sort(ArrayList.java:1721)
    at java.base/java.util.stream.SortedOps$RefSortingSink.end(SortedOps.java:392)
    at java.base/java.util.stream.Sink$ChainedReference.end(Sink.java:258)
    at java.base/java.util.stream.Sink$ChainedReference.end(Sink.java:258)
    at java.base/java.util.stream.Sink$ChainedReference.end(Sink.java:258)
    at java.base/java.util.stream.Sink$ChainedReference.end(Sink.java:258)
    at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:510)
    at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:499)
    at java.base/java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:921)
    at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
    at java.base/java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:682)
    at springfox.documentation.spring.web.plugins.WebMvcRequestHandlerProvider.requestHandlers(WebMvcRequestHandlerProvider.java:81)
    at java.base/java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:197)
    at java.base/java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.java:1625)
    at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:509)
    at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:499)
    at java.base/java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:921)
    at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
    at java.base/java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:682)
    at springfox.documentation.spring.web.plugins.AbstractDocumentationPluginsBootstrapper.withDefaults(AbstractDocumentationPluginsBootstrapper.java:107)
    at springfox.documentation.spring.web.plugins.AbstractDocumentationPluginsBootstrapper.buildContext(AbstractDocumentationPluginsBootstrapper.java:91)
    at springfox.documentation.spring.web.plugins.AbstractDocumentationPluginsBootstrapper.bootstrapDocumentationPlugins(AbstractDocumentationPluginsBootstrapper.java:82)
    at springfox.documentation.spring.web.plugins.DocumentationPluginsBootstrapper.start(DocumentationPluginsBootstrapper.java:100)
    at org.springframework.context.support.DefaultLifecycleProcessor.doStart(DefaultLifecycleProcessor.java:178)
    ... 14 common frames omitted

이게 스프링부트 2.6 출시되면서 PathPatternParser에 변경이 있었다고 하니, application.yaml에 이걸 추가해줘야한다.

spring.mvc.pathmatch.matching-strategy=ant_path_matcher

그리고 SpringFoxConfig에 다음과 같은 Bean도 추가해줘야한다.

@Bean
public WebMvcEndpointHandlerMapping webEndpointServletHandlerMapping(WebEndpointsSupplier webEndpointsSupplier,
        ServletEndpointsSupplier servletEndpointsSupplier, ControllerEndpointsSupplier controllerEndpointsSupplier,
        EndpointMediaTypes endpointMediaTypes, CorsEndpointProperties corsProperties,
        WebEndpointProperties webEndpointProperties, Environment environment) {
    List<ExposableEndpoint<?>> allEndpoints = new ArrayList();
    Collection<ExposableWebEndpoint> webEndpoints = webEndpointsSupplier.getEndpoints();
    allEndpoints.addAll(webEndpoints);
    allEndpoints.addAll(servletEndpointsSupplier.getEndpoints());
    allEndpoints.addAll(controllerEndpointsSupplier.getEndpoints());
    String basePath = webEndpointProperties.getBasePath();
    EndpointMapping endpointMapping = new EndpointMapping(basePath);
    boolean shouldRegisterLinksMapping = this.shouldRegisterLinksMapping(webEndpointProperties, environment,
            basePath);
    return new WebMvcEndpointHandlerMapping(endpointMapping, webEndpoints, endpointMediaTypes,
            corsProperties.toCorsConfiguration(), new EndpointLinksResolver(allEndpoints, basePath),
            shouldRegisterLinksMapping, null);
}

private boolean shouldRegisterLinksMapping(WebEndpointProperties webEndpointProperties, Environment environment,
        String basePath) {
    return webEndpointProperties.getDiscovery().isEnabled() && (StringUtils.hasText(basePath)
        || ManagementPortType.get(environment).equals(ManagementPortType.DIFFERENT));
}

다 이전에 언급한 PathPatternParser때문에 생기는 문제인데, Swagger가 api enpoint와 상세내용을 긁어오면서 문제가 생긴다. 대량의 URI path pattern이 있는 HTTP URL path에 사용하기 위해 디자인되었다고 한다.

 

이후 Spring Security가 설정되어 있다면 antMatchers에 Swagger 관련 endpoint들을 추가해준다.

.antMatchers("/auth/signup","/profile", "/health","/swagger-ui/**", "/v3/api-docs", "/v2/api-docs").permitAll()

그러면 v2/api-docs 로 가면

이런식으로 뜨는데 swagger-ui 로 가야 저 JSON들이 시각화되어 나타난다.

이런식으로 api endpoint들이 모두 수집되는데, 여기서 직접 request를 날려볼 수도 있다.