Resource Versioning Handler not being called if any FilterRegistrationBean is found

[iamareebjamal]

Issue:

If actuator starter dependency is included in the project, the resource strategies stop working, for instance, GZip or Content Versioning strategies are not called. Even AbstractResourceHandler stops getting invoked. Removing the actuator starter dependency makes the config start working again. This is reproducible on a simple https://start.spring.io template (with thymeleaf, web and actuator starters) as well. This also gets resolved on downgrading to 2.0.5. Sample repo is provided below

Sample Repo:

https://github.com/iamareebjamal/spring-boot-resource-versioning-bug

Environment:

Spring Boot 2.0.6

[philwebb]

Thanks for the detailed report and for the sample application. I'm still digging into the root cause, but it looks like the problem might be related to the @ConditionalOnMissingBean on the FilterRegistrationBean<ResourceUrlEncodingFilter> resourceUrlEncodingFilter() method in ThymeleafWebMvcConfiguration.

In 2.0.5 running with debug reports:

   ThymeleafAutoConfiguration.ThymeleafWebMvcConfiguration#resourceUrlEncodingFilter matched:
      - @ConditionalOnMissingBean (types: org.springframework.web.servlet.resource.ResourceUrlEncodingFilter; SearchStrategy: all) did not find any beans (OnBeanCondition)
      - @ConditionalOnEnabledResourceChain enabled (OnEnabledResourceChainCondition)

in 2.0.6

   ThymeleafAutoConfiguration.ThymeleafWebMvcConfiguration#resourceUrlEncodingFilter:
      Did not match:
         - @ConditionalOnMissingBean (types: org.springframework.boot.web.servlet.FilterRegistrationBean; SearchStrategy: all) found beans of type 'org.springframework.boot.web.servlet.FilterRegistrationBean' webMvcMetricsFilter (OnBeanCondition)

[philwebb]

Commits 64f04fc and 6cc272e changed resourceUrlEncodingFilter from a concrete bean of type ResourceUrlEncodingFilter to a FilterRegistrationBean. The @ConditionalOnMissingBean doesn't check generics so it now matches when any other FilterRegistrationBean exists (for example, when actuator adds one for metrics).

[philwebb]

@iamareebjamal Until we can fix this, you can work-around the issue by adding the following to your @SpringBootApplication class:

@Bean
public FilterRegistrationBean<ResourceUrlEncodingFilter> resourceUrlEncodingFilter() {
	FilterRegistrationBean<ResourceUrlEncodingFilter> registration = new FilterRegistrationBean<>(new ResourceUrlEncodingFilter());
	registration.setDispatcherTypes(DispatcherType.REQUEST, DispatcherType.ERROR);
	return registration;
}

[bclozel]

Should we reconsider #7475 ?

[wilkinsona]

It looks like it. An alternative would be to use a specific bean name when checking for a missing bean, but that feels more like a workaround than a long-term solution.

[philwebb]

For 2.0 we can rely on @ConditionalOnBean(ResourceUrlEncodingFilter). This won't detect if the user is adding FilterRegistrationBean, but it will restore 2.0.5 functionality.