Serving static resources with Spring WebFlux and Kotlin

When you start a WebFlux project you haven’t the support for static resources, like HTML, CSS and JS files, provided by Spring Boot project. Unfortunately how to solve this simple task isn’t so well documented, so I decided to write this post.

The simplest way I found is to define a resource router as you can see below:

import org.springframework.context.annotation.Bean
import org.springframework.context.annotation.Configuration
import org.springframework.core.io.ClassPathResource
import org.springframework.web.reactive.function.server.RouterFunctions.resources

@Configuration
class WebConfiguration {

  @Bean
  fun resRouter() = resources("/**", ClassPathResource("static/"))

}

Now you can run your application and navigate to:

http://localhost:8080/index.html

But if you try to remove the file name in the URL, you will receive a 404 error.

In order to define the file to serve as homepage, you need to define a route for the “/” path.

//...

  @Bean
  fun indexRouter(@Value("classpath:/static/index.html") html:  
    Resource) = router {
        GET("/") {
            ok().contentType(TEXT_HTML).syncBody(html)
        }
    }

//...

Now you can navigate to http://localhost:8080/ and view your static HTML page.