Support WebJars directly in Jersey

This is half question and half (potential) bug report. I’ve inquired about the problem in the webjars-locator project and was directed here.

I’m trying to get swagger-ui working in a version agnostic manner inside of Spring Boot with Jersey and Tomcat. According to the WebJars documentation, having a pom.xml similar to the following should allow me to access swagger-ui via http://localhost:8080/webjars/swagger-ui/ but it only works via http://localhost:8080/webjars/swagger-ui/3.6.1.

<dependencies>
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-jersey</artifactId>
    </dependency>
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-tomcat</artifactId>
    </dependency>
    <dependency>
      <groupId>org.webjars</groupId>
      <artifactId>swagger-ui</artifactId>
      <version>3.6.1</version>
    </dependency>
    <dependency>
      <groupId>org.webjars</groupId>
      <artifactId>webjars-locator</artifactId>
      <version>0.32-1</version>
    </dependency>
</dependencies>

Is there anything special I’d need to do to get webjars-locator working in this situation? It works just fine in spring-boot-starter-web which leads me to believe this is potentially a bug.

[w4tson]

I’ve managed to replicate some of the issue in a git repo. Instructions to reproduce are in the README.

I’ve done some analysis on this and would like to help fix.

As @philwebb mentioned the webjars functionality is getting implemented by org.springframework.web.servlet.resource.WebJarsResourceResolver. Unfortunately this is in the spring-mvc project and leverages the ResourceResolver mechanism which isn’t available to spring-jersey users.

I’ve dreamt up a couple of options

1. Allow the servlet 3.0 convention to statically serve webjars
2. A Jersey controller with regex of /webjars/.* to serve content
3. A servlet/filter that does the same

By all accounts a servlet 3.0 should serve static files in the META-INF/resources directory. The webjars documentation explains as such. I just can’t get this to work. Tried adding in the Tomcat DefaultServlet and setting Jersey to be a Filter but no joy.

Can someone steer me in the right direction?

[bclozel]

While this feature would be useful to Jersey users, I think we can’t really address this properly in Spring Boot. Spring Framework supports WebJars in the context of the resource handling feature, supporting serving static resources, cache busting, HTTP cache headers, etc.

Spring Boot should auto-configure this feature, once it’s supported officially by Jersey. Closing this issue for now, we should reopen it once it’s available in Jersey.