Strange behavior when overriding properties for a spring-boot application deployed as a WAR in a Tomcat - spring-boot

Question

I have a spring-boot application which I need to deploy as a WAR in a tomcat.
I also need to define / override some properties so that this application can work in this environment.
I was able to do so by creating a file tomcat/conf/Catalina/localhost/backend.xml with the same name as my WAR file. Here the content:
<?xml version="1.0" encoding="UTF-8"?>
<Context reloadable="true" crossContext="true" override="true" path="/back" docBase="/home/myAppUser/webapps/backend.war">
<Environment name="spring.profiles.active" value="prod" type="java.lang.String" />
<Environment name="application.attachmentBaseDirectory" value="/home/myAppUser/attachments" type="java.lang.String" />
<Environment name="application.redirect-url" value="http://myapp.mycompany.org/frontend" type="java.lang.String" />
</Context>
All environment variables but application.attachmentBaseDirectory work.
The application continue to use the one defined for my development environment on Windows: C:\tmp\attachments…
Yet, if I create a file /home/myAppUser/application.yml or /home/myAppUser/config/application.yml, the value is correctly overridden…
application:
attachmentBaseDirectory: /home/myAppUser/attachments
But if I define all the values inside this file in place of backend.xml, none of them but application.attachmentBaseDirectory work…
So here is my questions:
Why the overriding in tomcat/conf/Catalina/localhost/backend.xml isn't working for this value, but work for others?
How come the WAR is able to find the application.yml when running inside of a tomcat?
Why the application.attachmentBaseDirectory property does work from the application.yml file, but others don't?
Some more information:
Here the content on my ApplicationProperties.java.
#Component
#ConfigurationProperties("application")
public class ApplicationProperties {
/**
* The URL to which we should redirect the user once he is logged in the application.
*/
private String redirectUrl;
/**
* The base directory in which we should put the attachments.
*/
private String attachmentBaseDirectory;
}
This bean is then use in a #Controller for the redirectUrl to redirect to another web page, and in a #Service for the attachmentBaseDirectory to save files.

Answer 1

I finally found why the property application.attachmentBaseDirectory didn't work when set in tomcat/conf/Catalina/localhost/backend.xml:
It is because it was named application.attachmentBaseDirectory (camel case) and not application.attachment-base-directory (kebab case).
Spring-boot allow relaxed binding, but it seems that to be used through tomcat context, the kebab case way is the one to go.
Yet to solve:
How come the WAR is able to find the application.yml in the home directory when running inside tomcat?
I am suspecting that it is because I launch the tomcat from my home directory.
Why the application.attachmentBaseDirectory works from application.yml but others properties don't?