Springdoc-openapi: 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) [?:?]

[springdoc]

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();
    }

[springdoc]

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.

[springdoc]

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);
}