Vaadin Flow 14, Jetty embedded and static files - jar

Question

I'm trying to create app based on Jetty 9.4.20 (embedded) and Vaadin Flow 14.0.12.
It based on very nice project vaadin14-embedded-jetty.
I want to package app with one main-jar and all dependency libs must be in folder 'libs' near main-jar.
I remove maven-assembly-plugin, instead use maven-dependency-plugin and maven-jar-plugin. In maven-dependency-plugin i add section <execution>get-dependencies</execution> where i unpack directories META-INF/resources/,META-INF/services/ from Vaadin Flow libs to the result JAR.
In this case app work fine. But if i comment section <execution>get-dependencies</execution> then result package didn't contain that directories and app didn't work.
It just cannot give some static files from Vaadin Flow libs.
This error occurs only if i launch packaged app with ...
$ java -jar vaadin14-embedded-jetty-1.0-SNAPSHOT.jar
... but from Intellij Idea it launch correctly.
There was an opinion that is Jetty staring with wrong ClassLoader and cannot maintain requests to static files in Jar-libs.

Answer 1

The META-INF/services/ files MUST be maintained from the Jetty libs.
That's important for Jetty to use java.util.ServiceLoader.
If you are merging contents of JAR files into a single JAR file, that's called a "uber jar".
There are many techniques to do this, but if you are using maven-assembly-plugin or maven-dependency-plugin to build this "uber jar" then you will not be merging critical files that have the same name across multiple JAR files.
Consider using maven-shade-plugin and it's associated Resource Transformers to properly merge these files.
http://maven.apache.org/plugins/maven-shade-plugin/
http://maven.apache.org/plugins/maven-shade-plugin/examples/resource-transformers.html
The ServicesResourceTransformer is the one that merges META-INF/services/ files, use it.
As for static content, that works fine, but you have to setup your Base Resource properly.
Looking at your source, you do the following ...
final URI webRootUri = ManualJetty.class.getResource("/webapp/").toURI();
final WebAppContext context = new WebAppContext();
context.setBaseResource(Resource.newResource(webRootUri));
That won't work reliably in 100% of cases (as you have noticed when running in the IDE vs command line).
The Class.getResource(String) is only reliable if you lookup a file (not a directory).
Consider that the Jetty Project Embedded Cookbook recipes have techniques for this.
See:
WebAppContextFromClasspath.java
ResourceHandlerFromClasspath.java
DefaultServletFileServer.java
DefaultServletMultipleBases.java
XmlEnhancedServer.java
MultipartMimeUploadExample.java
Example:
// Figure out what path to serve content from
ClassLoader cl = ManualJetty.class.getClassLoader();
// We look for a file, as ClassLoader.getResource() is not
// designed to look for directories (we resolve the directory later)
URL f = cl.getResource("webapp/index.html");
if (f == null)
{
throw new RuntimeException("Unable to find resource directory");
}
// Resolve file to directory
URI webRootUri = f.toURI().resolve("./").normalize();
System.err.println("WebRoot is " + webRootUri);
WebAppContext context = new WebAppContext();
context.setBaseResource(Resource.newResource(webRootUri));