404 error with swagger-ui and spring webflux

Question

I am developping REST services with Spring Webflux and I want to produce documentation with Swagger2 for my API with. I discovered that Webflux is only supported with Swagger2 version 3.0.0 snapshot.

Here's my configuration :

• java 11
• maven 3

My SwaggerConfiguration bean looks like this

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import springfox.documentation.builders.ApiInfoBuilder;
import springfox.documentation.builders.PathSelectors;
import springfox.documentation.builders.RequestHandlerSelectors;
import springfox.documentation.spi.DocumentationType;
import springfox.documentation.spring.web.plugins.Docket;
import springfox.documentation.swagger2.annotations.EnableSwagger2WebFlux;

@Configuration
@EnableSwagger2WebFlux
public class SwaggerConfig {

    @Bean
    public Docket createRestApi() {
        return new Docket(DocumentationType.SWAGGER_2)
                .apiInfo(new ApiInfoBuilder()
                        .description("My Reactive API")
                        .title("My Domain object API")
                        .version("1.0.0")
                        .build())
                .enable(true)
                .select()
                .apis(RequestHandlerSelectors.basePackage("com.mypackage.service.myobject.controller"))
                .paths(PathSelectors.any())
                .build();

    }
}

My springboot app is defined like this :

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.web.reactive.config.EnableWebFlux;

@SpringBootApplication
@EnableWebFlux
public class Application {
    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }
}

Here's my pom configuration

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.2.1.RELEASE</version>
</parent>

<properties>
    <swagger.version>3.0.0-SNAPSHOT</swagger.version>
</properties>

<dependencies>
    <dependency>
        <groupId>io.projectreactor</groupId>
        <artifactId>reactor-test</artifactId>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>org.springframework.integration</groupId>
        <artifactId>spring-integration-webflux</artifactId>
    </dependency>
    <dependency>
        <groupId>io.springfox</groupId>
        <artifactId>springfox-swagger2</artifactId>
        <version>${swagger.version}</version>
    </dependency>
    <dependency>
        <groupId>io.springfox</groupId>
        <artifactId>springfox-spring-webflux</artifactId>
        <version>${swagger.version}</version>
    </dependency>
    <dependency>
        <groupId>io.springfox</groupId>
        <artifactId>springfox-spring-integration-webflux</artifactId>
        <version>${swagger.version}</version>
    </dependency>
    <dependency>
        <groupId>io.springfox</groupId>
        <artifactId>springfox-swagger-ui</artifactId>
        <version>${swagger.version}</version>
    </dependency>
</dependencies>

However, I get a 404 error when I type http://localhost:8080/swagger-ui.html in my browser. If I type http://localhost:8080/v2/api-docs, I get the swagger document in json for my API.

I run my springboot app in debug under Intellij. I try to run the fat jar in command line: same issue. Does somebody know what is wrong with my configuration?

Thanks

Answer 1

Found it!

I have to register a webflux resource handler for swagger-ui like this.

import org.springframework.context.annotation.Configuration;
import org.springframework.web.reactive.config.ResourceHandlerRegistry;
import org.springframework.web.reactive.config.WebFluxConfigurer;

@Configuration
public class WebfluxConfig implements WebFluxConfigurer {

    @Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {

        registry.addResourceHandler("/swagger-ui.html**")
                .addResourceLocations("classpath:/META-INF/resources/");

        registry.addResourceHandler("/webjars/**")
                .addResourceLocations("classpath:/META-INF/resources/webjars/");
    }
}

Problem solved!