Use of @EnableWebMvc in app breaks swagger-ui.html redirect

[andygoossens]

(Identical to closed issue #150, but now with steps on how it can be reproduced:)

The use of @EnableWebMvc in some of my apps breaks the redirect from /swagger-ui.html to /swagger-ui/index.html?url=/v3/api-docs. Visiting the destination URL directly works.

Issue might be caused by having @EnableWebMvc on SwaggerConfig as well. Most likely it can only appear once in a Spring app. Ideally, Springdoc works regardless whether that annotation is already present in app (or any library it might use).

To reproduce:

• checkout springdoc-openapi-demos project @ https://github.com/springdoc/springdoc-openapi-demos
• add @EnableWebMvc on class org.springdoc.demo.app1.Application
• run org.springdoc.demo.app1.Application
• visit http://localhost:8080/swagger-ui.html and notice that it doesn't work

The stacktrace looks like this:

2019-11-08 12:51:31.774 ERROR 26637 --- [nio-8080-exec-7] o.a.c.c.C.[.[.[.[dispatcherServlet]      : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Could not resolve view with name 'redirect:/swagger-ui/index.html?url=/v3/api-docs&validatorUrl=' in servlet with name 'dispatcherServlet'] with root cause

javax.servlet.ServletException: Could not resolve view with name 'redirect:/swagger-ui/index.html?url=/v3/api-docs&validatorUrl=' in servlet with name 'dispatcherServlet'
	at org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1351) ~[spring-webmvc-5.1.7.RELEASE.jar:5.1.7.RELEASE]
	at org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:1117) ~[spring-webmvc-5.1.7.RELEASE.jar:5.1.7.RELEASE]
	at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1056) ~[spring-webmvc-5.1.7.RELEASE.jar:5.1.7.RELEASE]
	at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:942) ~[spring-webmvc-5.1.7.RELEASE.jar:5.1.7.RELEASE]
	at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1005) ~[spring-webmvc-5.1.7.RELEASE.jar:5.1.7.RELEASE]
	at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:897) ~[spring-webmvc-5.1.7.RELEASE.jar:5.1.7.RELEASE]
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:634) ~[tomcat-embed-core-9.0.19.jar:9.0.19]
	at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:882) ~[spring-webmvc-5.1.7.RELEASE.jar:5.1.7.RELEASE]
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:741) ~[tomcat-embed-core-9.0.19.jar:9.0.19]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) ~[tomcat-embed-core-9.0.19.jar:9.0.19]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.19.jar:9.0.19]
	at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) ~[tomcat-embed-websocket-9.0.19.jar:9.0.19]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.19.jar:9.0.19]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.19.jar:9.0.19]
	at org.springframework.boot.actuate.web.trace.servlet.HttpTraceFilter.doFilterInternal(HttpTraceFilter.java:90) ~[spring-boot-actuator-2.1.5.RELEASE.jar:2.1.5.RELEASE]
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-5.1.7.RELEASE.jar:5.1.7.RELEASE]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.19.jar:9.0.19]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.19.jar:9.0.19]
	at org.springframework.cloud.sleuth.instrument.web.ExceptionLoggingFilter.doFilter(ExceptionLoggingFilter.java:50) ~[spring-cloud-sleuth-core-2.1.1.RELEASE.jar:2.1.1.RELEASE]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.19.jar:9.0.19]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.19.jar:9.0.19]
	at brave.servlet.TracingFilter.doFilter(TracingFilter.java:86) ~[brave-instrumentation-servlet-5.6.1.jar:?]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.19.jar:9.0.19]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.19.jar:9.0.19]
	at org.springframework.boot.actuate.metrics.web.servlet.WebMvcMetricsFilter.filterAndRecordMetrics(WebMvcMetricsFilter.java:117) ~[spring-boot-actuator-2.1.5.RELEASE.jar:2.1.5.RELEASE]
	at org.springframework.boot.actuate.metrics.web.servlet.WebMvcMetricsFilter.doFilterInternal(WebMvcMetricsFilter.java:106) ~[spring-boot-actuator-2.1.5.RELEASE.jar:2.1.5.RELEASE]
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-5.1.7.RELEASE.jar:5.1.7.RELEASE]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.19.jar:9.0.19]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.19.jar:9.0.19]
	at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:200) ~[spring-web-5.1.7.RELEASE.jar:5.1.7.RELEASE]
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-5.1.7.RELEASE.jar:5.1.7.RELEASE]
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.19.jar:9.0.19]
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.19.jar:9.0.19]
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:200) [tomcat-embed-core-9.0.19.jar:9.0.19]
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) [tomcat-embed-core-9.0.19.jar:9.0.19]
	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:490) [tomcat-embed-core-9.0.19.jar:9.0.19]
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139) [tomcat-embed-core-9.0.19.jar:9.0.19]
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) [tomcat-embed-core-9.0.19.jar:9.0.19]
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74) [tomcat-embed-core-9.0.19.jar:9.0.19]
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343) [tomcat-embed-core-9.0.19.jar:9.0.19]
	at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:408) [tomcat-embed-core-9.0.19.jar:9.0.19]
	at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) [tomcat-embed-core-9.0.19.jar:9.0.19]
	at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:836) [tomcat-embed-core-9.0.19.jar:9.0.19]
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1747) [tomcat-embed-core-9.0.19.jar:9.0.19]
	at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-9.0.19.jar:9.0.19]
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128) [?:?]
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628) [?:?]
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-9.0.19.jar:9.0.19]
	at java.lang.Thread.run(Thread.java:834) [?:?]

Hi,

Please have a look at the spring documentation:

• https://docs.spring.io/spring-boot/docs/current/reference/html/spring-boot-features.html#boot-features-developing-web-applications

If you want to take complete control of Spring MVC, you can add your own @configuration annotated with @EnableWebMvc.

So you just add, your own @Configuration class with @EnableWebMvc annotation.

[darc1]

I faced similar problem, what solved the issue for me is adding this to the Web Config:

    @Bean
    public InternalResourceViewResolver defaultViewResolver() {
        return new InternalResourceViewResolver();
    }

Thank you @darc1 for sharing your feedback.

[Aloren]

@springdoc @EnableWebMvc is only needed in non spring-boot applications.
So the issue still exists for Spring Boot applications. I've checked locally removing @EnableWebMvc from SwaggerConfig fixes an issue.
I think that configuration should be separate for Spring Boot and Spring applications. Moreover I would rather replace component scan with autoconfiguration approach for Spring Boot configuration as it is the more recommended and extensible approach.

Hi,

Since v1.2.19, component scan is removed and replaced with autoconfiguration.

[sbjw]

WebMvcConfigurationSupport.java

if (names.length == 1) {
registry.getViewResolvers().add(new InternalResourceViewResolver());
}

In WebMvcConfigurationSupport.java , has the code name.length == 1. but when debug ,name.length != 1. so is do not pass the if quote.

so the answer is to override the method configureViewResolvers, and regist it in you SpringMvcConfig bean like this:

@Override
protected void configureViewResolvers(ViewResolverRegistry registry) {
    registry.viewResolver(new InternalResourceViewResolver());
    super.configureViewResolvers(registry);
}