Configure embedded containers to load static resources from fat jar's BOOT-INF/classes/META-INF/resources

[mcirikovic]

Might be related to: #7595 (or at least to a comment in this issue)

Starting with 1.4.3, our JSF application isn't processing JSF pages anymore.

• The application still starts and seems to work, but when we call a JSF page, it returns an error:
  /index.xhtml Not Found in ExternalContext as a Resource
• After reading JarLauncher configures the class path such that resources are found twice #7595, i switched back to 1.5.1, but used the spring-boot-maven-plugin from version 1.4.2. Now the application starts with version 1.5.1 but JSF is still working.

I've appended a small example application. After started, call http://localhost:8085/index.xhtml.

• If Spring Boot <=1.4.2 is used, the page shows something like "--|test value|--".
• If Spring Boot >= 1.4.3 is used, an error page is displayed
• If Spring Boot >= 1.4.3 with spring-boot-maven-plugin:1.4.2 is used, no error occurs and the expected "--|test value|--" is shown

BugTest.zip

BTW: If you start the application in Eclipse with the Spring Plugin, the result depends on your eclipse environment (for some developers it works, for some not - guess it depends, which loader is used by eclipse),

[wilkinsona]

The change that has stopped this from working is intentional as it aligns Spring Boot more closely with the Servlet spec.

The spec states that resources in META-INF/resources should be loaded from jars packaged in WEB-INF/lib but should not be loaded from META-INF/resources within the main archive. In 1.4.2 and earlier (and only with Tomcat (see #8299)) we loaded resources from META-INF/resources within the main archive (actually from BOOT-INF/classes/META-INF/resources). In 1.4.3 and later we now only load resources from META-INF/resources of a jar packaged in BOOT-INF/lib.

The one significant difference between a jar and a war file is that a war project can use src/main/webapp to package resources in the root of the archive from where they will be accessible. This isn't an option with a jar. We can consider officially supporting BOOT-INF/classes/META-INF/resources as an extension to what the Servlet spec suggests, but I'm yet to convince myself that it's a good idea.

In the meantime, you have two options here:

• Package your application as a war file and use src/main/webapp/ for your resources rather than src/main/resources/META-INF/resources/. You can still launch it using java -jar.
• Continue packaging your application as a jar file, but move your resources into a separate module and make your app depend on the module such that its jar is packaged in BOOT-INF/lib

I'm going to close this in favour of #8299 which will make resource handling consistent across all three containers. We'll consider supporting BOOT-INF/classes/META-INF/resources as part of that.

[wilkinsona]

On second thoughts, this would be better handled as a separate issue rather than rolling it into #8299