Allow early ServletRequest Autowiring with embedded containers

[pfoermer]

Spring Boot Version: 1.5.13.RELEASE

Setup
ApplicationContext with a Bean declared with an autowire dependency to HttpServletRequest (the used ApplicationContext is a little bit more complex).

Problem
For a non embedded environment (Tomcat deployment) the application context boots successfully. For an embedded environment, the application context fails to start with the exception:

....NoSuchBeanDefinitionException: No qualifying bean of type 'javax.servlet.http.HttpServletRequest' available: expected at least 1 bean which qualifies as autowire candidate.

Reason
The HttpServletRequest substitution is performed by an ObjectFactory registered by org.springframework.web.context.support.WebApplicationContextUtils.registerWebApplicationScopes(...). The registerWebApplicationScopes(...) call is performed by EmbeddedWebApplicationContext.selfInitialize(...). For an embedded environment the method EmbeddedWebApplicationContext.createEmbeddedServletContainer() is invoked previous to the initializer which causes Eager Bean creation of the ApplicationContext.

Expected
HttpServletRequest is resolved, no matter if it is an embedded or non embedded environment.

[philwebb]

Could you please share a sample application that shows the problem.

[pfoermer]

Hi @philwebb,

I can not provide you the real business application, as it is closed source, but here is a sample Maven application which should show the problem:
issue-14990.zip

Please start "sample.App".

Like noted in "sample.Config" in my opinion FactoryBean, Advisor or similar things seem to force eager bean creation, as spring is otherwise unable to determine target bean type for query operations of org.springframework.beans.factory.support.DefaultListableBeanFactory. See also workarounds for this eager bean creation issue in org.springframework.boot.autoconfigure.condition.BeanTypeRegistry used for Condition evaluation.

[philwebb]

Thanks @pfoermer

[philwebb]

For a non embedded environment (Tomcat deployment) the application context boots successfully. For an embedded environment, the application context fails to start with the exception

I quite surprised that the application context boots when running under Tomcat. I've not really had a chance to dig into why that might be. I think the real issue here is that the HttpServletRequest can only be obtained when a request is in progress.

Although WebApplicationContextUtils.registerWebApplicationScopes does call beanFactory.registerResolvableDependency(ServletRequest.class, new RequestObjectFactory());, resolving a ServletRequest only really makes sense in a @Scope("request") bean. In your case, your Interceptor is a singleton bean and Spring will try to initialize early (before any request is happening).

I would suggest refactoring your code to use an javax.inject.Provider<HttpServletRequest> which you then call to get the request when needed (assuming you are only intercepting methods that are invoked when a request is active).

Alternatively you could call RequestContextHolder directly.

[pfoermer]

Hi @philwebb,

thank you for suggestions.

I would like to please you to take also a look at https://docs.spring.io/spring/docs/4.3.20.RELEASE/spring-framework-reference/htmlsingle/#beans-factory-scopes-other-injection and org.springframework.beans.factory.support.AutowireUtils.resolveAutowiringValue(...).

For HttpServletRequest Spring Core creates out of the box a Proxy Handler, like for EntityManager injection.

Here is also a remote debug screenshot where you can see, that Spring created a proxy object for the HttpServletRequest.