I have child servlets on different ports (i.e. port 8080 to servlet1, port 8081 to servlet2, ...) on Spring Boot 2.5.9. However, once I upgrade to 2.6.3, I am not able to access to the child servlets even though the servlets are starting correctly.

Here is my setup:

// App.java
public class App {
  public static void main(String[] args) {
    new SpringApplicationBuilder()
    .parent(Config.class)
    .web(WebApplicationType.NONE)

    .child(Servlet1.class)
    .web(WebApplicationType.SERVLET)
    .child(Servlet2.class)
    .web(WebApplicationType.SERVLET)
    .child(Servlet3.class)
    .web(WebApplicationType.SERVLET)
    .run(args);
  }
}

// Config.java
@Configuration
@ComponentScan("...")
@ConfigurationPropertiesScan
public class Config {
  // ...
}

// Servlet1.java, Servlet2.java, Servlet3.java
@Configuration
@ComponentScan("...")
@PropertySource("classpath:servlet1/servlet1.properties") // servlet2, servlet3
@EnableAutoConfiguration
public class Servlet1 { // Servlet2, Servlet3
  // ...
}

# File: `src/main/resources/servlet1/servlet1.properties`
server.port=8080
server.servlet.context-path=/
spring.resources.static-locations=/servlet1/foo
spring.application.admin.enabled=false
spring.application.admin.jmx-name=org.springframework.boot:type=servlet1,name=servlet1app
spring.mvc.pathmatch.matching-strategy=ant_path_matcher

# File: `src/main/resources/servlet1/servlet2.properties`
server.port=8081
... same as above (with different name) ...

# File: `src/main/resources/servlet1/servlet3.properties`
server.port=8082
... same as above (with different name) ...

With the above code setup, I have servlet1 at port 8080, servlet2 at port 8081, and servlet3 at port 8082.

But here is the thing - my project is Single Page Application (SPA). Therefore, I have a special setup for that:

// HomeController.java (for each servlet)
@Controller
public class HomeController {
  @RequestMapping(value={"/**/{[path:[^\\.]*}"}, method=RequestMethod.GET)
  public String defaultRoute(HttpServletRequest request) {
    return "forward:/";
  }
}

As you see, to use /**/{[path:[^\\.]*}, I have added spring.mvc.pathmatch.matching-strategy=ant_path_matcher in the properties files (without this, the 2.6.x app won't start up).

Once I upgrade to 2.6.3, it seems the child servlets start up fine - however, when I go to localhost:8080 (or 8081, 8082), it doesn't hit HomeController.java, giving 404 error. Moreover, it seems the child servlet doesn't recognize its port number.

I am not sure what I've missed - please help me out.

Thank you, Spring Boot dev team!

Comment From: mbhave

@LouisWayne In order for us to be able to reproduce the issue you've described, can you please turn the code snippets into a minimal sample that we can run ourselves? Copy-pasting snippets can lead to errors which might not result in accurate diagnosis of the problem. You can share such a sample with us by zipping it up and attaching it to this issue or pushing it to a separate repository on GitHub.

Comment From: LouisWayne

Thank you for the reply @mbhave !! I will provide the sample code in a few days!

Comment From: LouisWayne

Thanks for waiting, @mbhave ! Please see the attached sample source code to reproduce the issue.

You can reproduce the issue by modifying <version>2.5.9</version> in pom.xml - and the main file is App.java. Please let me know if you have any questions.

Thank you, Spring Boot devs!!!!!

servletExample.zip

Comment From: wilkinsona

Thanks for the sample. The property that you are using to configure your static resource location is incorrect with Spring Boot 2.6. It should be spring.web.resources.static-locations. The property that you are using has been deprecated since 2.4. Support was removed entirely in 2.6. Making this change in servlet1.properties, servlet2.properties, and servlet3.properties allows each child web application to serve its welcome page.

Comment From: LouisWayne

@wilkinsona , thank you so much for your time!

Yes, once I changed it from spring.resources.static-locations=/servlet1/dist/ to spring.web.resources.static-locations=/servlet1/dist/, everything works fine!

Thank you for making & updating this wonderful open source project. Long live Spring Boot!

♡