SpringBoot controller redirection doesn't work - spring-boot

Question

Hitting the / directory of my Rest app doesn't redirect to what I what, but just print the redirection directive on the screen: "redirect:swagger-ui.html"
My controller:
import org.springframework.web.bind.annotation.RequestMapping
import org.springframework.web.bind.annotation.RestController
#RestController
class HomeController(val info: InfoProperties) {
#RequestMapping("/")
fun home(): String {
return "redirect:/swagger-ui.html"
}
}

Answer 1

Using curl, we see that the answer is text (Content-Type: text/plain;charset=UTF-8), hence the simple unexpected text output:
> curl -v "http://localhost:8080/"
* Trying ::1...
* TCP_NODELAY set
* Connected to localhost (::1) port 8080 (#0)
> GET / HTTP/1.1
> Host: localhost:8080
> User-Agent: curl/7.54.0
> Accept: * / *
>
< HTTP/1.1 200 OK
< Connection: keep-alive
< Content-Type: text/plain;charset=UTF-8
< Content-Length: 25
< Date: Fri, 15 Mar 2019 17:52:32 GMT
<
* Connection #0 to host localhost left intact
redirect:/swagger-ui.html
The #RestController annotation is a specialized version of the controller. It includes the #Controller and #ResponseBody annotations, and #ResponseBody is the cause of our problem.
So to fix this, replace the #RestController annotation with the more generic #Controller one:
import org.springframework.web.bind.annotation.RequestMapping
import org.springframework.stereotype.Controller
#Controller
class HomeController(val info: InfoProperties) {
#RequestMapping("/")
fun home(): String {
return "redirect:/swagger-ui.html"
}
}
The redirection now works properly.

Answer 2

You can actually achieve this without changing #RestController to #Controller. What you need to do is return a RedirectView instead of a string. This is how I have it working in java:
#RestController
#ApiIgnore
public class ApiDocsRedirectController {
#RequestMapping(value = {"/","/api-docs","/v3/api-docs"})
public RedirectView redirect() {
return new RedirectView("/swagger-ui.html");
}
}