APACHE MAVEN Robert Scholte ( @rfscholte ) Developer vs. Maven? - - PowerPoint PPT Presentation

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APACHE MAVEN Robert Scholte ( @rfscholte ) Developer vs. Maven? - - PowerPoint PPT Presentation

Feb 22, 2024 554 likes •1.12k views

WHEN FIGHTING APACHE MAVEN Robert Scholte ( @rfscholte ) Developer vs. Maven? Feels like Terminator 1 Should be Terminator 2 Developer with Maven! Feels like Terminator 1 Should be Terminator 2 Reason for a fight? #fail Setup (no

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WHEN FIGHTING APACHE MAVEN…

Robert Scholte ( @rfscholte )

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Developer vs. Maven?

Feels like Terminator 1 Should be Terminator 2

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Developer with Maven!

Feels like Terminator 1 Should be Terminator 2

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Reason for a fight? #fail

■ Setup (no plug ‘n’ play) ■ Adding/removing code/plugins/… ■ Suddenly broken

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The situation

■ An unknown huge multilevel Maven Multimodule Project ■ We suddenly have a FAILURE: – CI Server – Maven Commandline – IDE

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Is it structural?

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IF YOU CANNOT REPRODUCE THE ISSUE, THEN IT IS NOT A BUG

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Analysis

Options tions Descrip scription ion

  • v,--version

Display version information

  • V,--show-version

Display version information WITHOUT stopping build

  • e,--errors

Produce execution error messages

  • X,--debug

Produce execution debug output

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Most likely causes

■ Your project / code :P ■ Maven Plugin ■ External Tool (java, javac, javadoc, …) ■ Maven

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If message doesn’t help

■ Google ■ Stack Overflow ■ Documentation ■ Issue management system

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Isolate the issue

mvn <phase> -pl :<artifactId> -am

Options

  • ns

Descr cript ption ion

  • pl,--projects <arg>

Comma-delimited list of specified reactor projects to build instead of all projects. A project can be specified by [groupId]:artifactId or by its relative path

  • am,--also-make

If project list is specified, also build projects required by the list

  • amd,--also-make-

dependents If project list is specified, also build projects that depend on projects on the list

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In case of external code: Sometimes reading code is enough

■ Github ■ JXR pages

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In search of regression with GIT

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GIT bisect

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Most likely solution

■ Fix your code :P ■ Upgrade to a more recent version – Dependencies – Plugins ■ Patch / fix others code

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No more fighting

Let’s go for quick and dirty

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■ The pom is a strict XML configuration file ■ Still… people can be VERY creative

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#1 Extending parent pattern

<parent> <groupId>com.acme.product</groupId> <artifactId>parent</artifactId> <version>9</version> </parent> <artifactId>parent</artifactId> <version>10</version>

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Discovery

■ ModelValidator ■ Check for circular references

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Why Dirty?

■ Increase number of downloads ■ Getting Effective Model is complex process

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#2 Replacing pom.xml

<plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-deploy-plugin</artifactId> <version>2.7</version> <configuration> <pomFile File>cus custom.

  • m.po

pom</ </pom pomFil File> > </configuration> </plugin>

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Discovery

■ Code refactoring to support – installAtEnd – deployAtEnd

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Why Dirty?

■ No guarantee pom is valid

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Solution

■ Introduction flatten-maven-plugin – “transforms” original pom.xml – Can apply effective pom elements – Can remove elements ■ Experience will be used in Maven4 ■ Experimental feature likely in Maven 3.7.0 – maven.experimental.buildconsumer

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#3 Bind to none-phase

■ Disable predefined or inherited plugin executions ■ E.g. replace surefire with junit-platform-maven-plugin

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<plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-surefire-plugin</artifactId> <executions> <execution> <id>default-test</id> <phase>none</phase> </execution> </executions> </plugin>

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Why dirty?

“You should always listen to your parent” (that’s why I don’t like structural ‘skipping’)

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#4 Sharing local repo

Slow wifi / connection Workshop that requires more plugins/dependencies than expected Solution: memorystick ?!?!

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Mock Repository Manager

  • rg.codehaus.mojo:mrm-maven-plugin:run

mrm:run

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When going for quick and dirty…

■ Commandline arguments ■ Pom.xml

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You have one custom requirement

.. But there’s no maven-plugin for it ( and don’t want to write one... ) Inside pom execution:

  • maven-antrun-plugin
  • Executes Ant scripts
  • maven-scripting-plugin
  • Uses the Scripting API (JSR223)
  • exec-maven-plugin
  • Executes commandline or Java’s main(args)
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You need to manipulate Maven

■ Maven Extensions ■ Custom Maven Builder

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Understanding properties

■ Project ■ Settings (via profile properties) ■ System Properties ■ Commandline ( -Dkey=value )

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testFailureIgnore

Name Type Since Descr crip ipti tion

  • n

<testFailureIgnore> boolean

  • Set this to "true" to ignore a failure during
  • testing. Its use is NOT RECOMMENDED, but

quite convenient on occasion. Defaul ult t value e is: false. User property ty is: maven.test.failure.ignore.

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Replace default value

<properties> <maven.test.failure.ignore>true</maven.test.failure.ignore> </properties>

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Replace expression

<properties> <surefire.failureIgnore>false</surefire.failureIgnore> </properties> … <configuration> <testFailureIgnore> ${surefire.failureIgnore} </ testFailureIgnore> </configuration>

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Replace with constant

<configuration> <testFailureIgnore>false</testFailureIgnore> </configuration>

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Making friends

<configuration> <skipTests>false</skipTests> </configuration>

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The ‘evil’ jenkinsci maven-plugin

■ Why does it continue after a failed test??? ■ h.m.r.SurefireArchiver L87-L114

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Commandline arguments

What will happen when you execute ‘mvn deploy -DjavaVersion=13’ ?

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spring-boot-dependencies

What will happen when you execute ‘mvn deploy -Dspring.version=5.1.0.RELEASE’ ?

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“ARGUMENTS SHOULD NEVER HAVE EFFECT ON THE CREATED ARTIFACTS”

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Clean Install

■ Maven is about convention of configuration ■ If the convention was ‘clean install’, you should simply execute ‘mvn’

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Clean Install is not quick, just dirty

Clean lifecycle

Pha hase se Bindi ding ng pre-clean clean clean:clean (remove target directory) post-clean

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Clean

■ Delete and re-place (same) files is waste of resources ■ Most maven-plugins are aware if they must execute their task Avoid “clean”

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Clean Install is not quick, just dirty

Build / default lifecycle

Phase se Bind nding ing (for every packaging ging) … install install:install (copy artifact to local repo) deploy deploy:deploy (upload to remote repo)

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Install

Maven 2:

  • Not aware of ‘reactor’
  • Dependencies had to exist in local repo.

Maven 3:

  • ‘reactor’ aware
  • No need for ‘install’ anymore
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Avoid Clean, Avoid Install

Introducing the Maven CI Extension

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Ultimate hack:

just fork and re-version

Ensure no conflicts with official future versions e.g. 3.6.3-rfscholte-SNAPSHOT

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Up for Grabs

■ ~60-80% of Java Project/Developers use Maven ■ The Apache Maven Project holds ~95 (sub)projects ■ Maintained by ~5-10 active volunteers (No Company!) ■ Let’s restore the balance! ■ https://s.apache.org/up-for-grabs_maven ■ https://maven.apache.org/guides/development/guide-committer-school.html

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THANK YOU AND HAPPY HACKING!