Jürgen Weber commented on MSHADE-287:

We had a case where a Spring Boot application would work standalone, but not in 
a JBoss .war. ( [1]) Cause was a different classpath order in WEB-INF/lib

The Spring Boot application's classpath (and its order) is defined by pom.xml, 
but the order of the jars in WEB-INF/lib is undefined (actually it is the 
result of java.io.File.list() which depends on the underlaying filesystem 

A work around for the order problem in WEB-INF/lib is:

for jar in reverse(classpath)

     unpack jar overwrite=true into directory d

create jar of d

This jar will show the same resources as the original pom classpath.

Of course one can implement this with a few lines of python or bash, but it 
would be great, if this could be done with a Maven plugin.


 [1] https://marc.info/?l=shibboleth-users&m=152209257717870&w=2


> honor classpath order
> ---------------------
>                 Key: MSHADE-287
>                 URL: https://issues.apache.org/jira/browse/MSHADE-287
>             Project: Maven Shade Plugin
>          Issue Type: Improvement
>            Reporter: Jürgen Weber
>            Priority: Major
> Shade Plugin should be able to honor classpath order semantics: -cp 
> a.jar:b.jar has the effect that resources in b.jar are not visible if also in 
> a.jar
> It should be possible to have the same effect with Shade Plugin: iterate for 
> last to first in classpath: extract current element overwriting content of 
> previous extracted.
> use case:
> running an app with Maven has a defined classpath order, whereas the order of 
> jars in WEB-INF/lib is rather random. So you could build an ueber jar 
> containing all jars of lib which would result in the desired class order.
> This is currently not possible with 
> org.apache.maven.plugins.shade.ShadeRequest as the input jars are in a 
> java.util.Set which has no order.
> See 
> [https://stackoverflow.com/questions/4466526/order-of-class-loading-from-a-war-file]
> [https://stackoverflow.com/questions/2021227/control-the-classpath-ordering-of-jars-in-web-inf-lib-on-tomcat-5]

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