Web fragments (attempt #2)

[Vlatombe]

• Reapply "[JENKINS-75174] Move existing web.xml to web-fragment.xml under core ([JENKINS-75174] Move existing web.xml to web-fragment.xml under core #10185)" (Revert "[JENKINS-75174] Move existing web.xml to web-fragment.xml under core (#10185)" #10225)
• Update jetty plugin configuration for configuration discovery

For running plugins with mvn hpi:run, It is necessary to update parent pom to 5.7 or later (requires hpi plugin 3.61 or later)

See JENKINS-XXXXX.

Testing done

• Unit tests relying on JenkinsRule
• Unit tests relying on RealJenkinsRule
• Starting Jenkins with mvn -pl war jetty:run
• Starting a plugin with mvn hpi:run

Proposed changelog entries

• Developer: to test plugins against this Jenkins version, please update plugin parent pom to version 5.7 or later.

Proposed upgrade guidelines

N/A

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@mention

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[Vlatombe]

While investigating some warnings during the startup, I realised that the jetty-maven-plugin already include core classes and resources from the module itself and not from the local maven repository (as long as mvn -pl war jetty:run is used).

Which means these extra classpath entries shouldn't be necessary to get live updates through hot reload.

Unfortunately, hot reload currently fails with

java.nio.file.ClosedFileSystemException
    at jdk.nio.zipfs.ZipFileSystem.ensureOpen (ZipFileSystem.java:1635)
    at jdk.nio.zipfs.ZipFileSystem.exists (ZipFileSystem.java:657)
    at jdk.nio.zipfs.ZipPath.exists (ZipPath.java:905)
    at jdk.nio.zipfs.ZipFileSystemProvider.exists (ZipFileSystemProvider.java:197)
    at java.nio.file.Files.exists (Files.java:2515)
    at org.eclipse.jetty.util.resource.PathResource.exists (PathResource.java:187)
    at org.eclipse.jetty.ee9.webapp.WebAppClassLoader.addClassPath (WebAppClassLoader.java:225)
    at org.eclipse.jetty.ee9.webapp.WebAppClassLoader.<init> (WebAppClassLoader.java:192)
    at org.eclipse.jetty.ee9.webapp.WebAppContext.configureClassLoader (WebAppContext.java:504)
    at org.eclipse.jetty.ee9.webapp.WebAppContext.preConfigure (WebAppContext.java:477)
    at org.eclipse.jetty.ee9.webapp.WebAppContext.doStart (WebAppContext.java:527)
    at org.eclipse.jetty.ee9.maven.plugin.MavenWebAppContext.doStart (MavenWebAppContext.java:313)
    at org.eclipse.jetty.util.component.AbstractLifeCycle.start (AbstractLifeCycle.java:93)
    at org.eclipse.jetty.ee9.maven.plugin.JettyEmbedder.redeployWebApp (JettyEmbedder.java:64)
    at org.eclipse.jetty.ee9.maven.plugin.JettyRunMojo.restartWebApp (JettyRunMojo.java:362)
    at org.eclipse.jetty.ee9.maven.plugin.JettyRunMojo$2.consoleEvent (JettyRunMojo.java:198)
    at org.eclipse.jetty.maven.ConsoleReader.signalEvent (ConsoleReader.java:64)
    at org.eclipse.jetty.maven.ConsoleReader.run (ConsoleReader.java:57)
    at java.lang.Thread.run (Thread.java:1583)

that seems to be caused by a JDK bug? (see jetty/jetty.project#11548)

[jglick]

I have had problems with the JDK ZIP file code for most of my adult life.

[daniel-beck]

This broke live updates of resources like Jelly files. What motivated this change?

[Vlatombe]

Ah, indeed I shouldn't have removed ${project.basedir}/../core/src/main/resources, only ${project.basedir}/../core/target/classes. Sorry for that.

[timja]

Thanks, I tested jetty:run locally

[jglick]

You have to wonder how much of this stuff actually still does anything useful…

[timja]

/label ready-for-merge

---

This PR is now ready for merge, after ~24 hours, we will merge it if there's no negative feedback.

Thanks!

[daniel-beck]

Caused JENKINS-75280.