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What does a Maven Artifact means in a context of runnable jar project? [duplicate]

I have a project that consist of 3 different libraries. When I run install script it takes all libraries from repo and run mvn clean install on them. But this version of library already installed in repo. Is there a way to skip install phase if version in pom.xml equal version in my local repo.
I know that I can use local repo and just set dependencies. But my boss want that our project can build only with public repos and without any our repos.

You can bypass like this
-Dmaven.install.skip=true
<profiles>
<profile>
<id>skipInstall</id>
<activation>
<property>
<name>maven.install.skip</name>
<value>true</value>
</property>
</activation>
<build>
<pluginManagement>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-install-plugin</artifactId>
<executions>
<execution>
<id>default-install</id>
<phase>none</phase>
</execution>
</executions>
</plugin>
</plugins>
</pluginManagement>
</build>
</profile>
Last week Olivier Lamy patched this jira.
MINSTALL-73

Most maven plugins can be skipped by specifying something like:
<plugin>
<artifactId>maven-install-plugin</artifactId>
<version>X.Y</version>
<configuration>
<skip>true</skip>
</configuration>
</plugin>
you can also set up build profiles to set properties and use that to determine the value. for example, running the command: mvn -Pexample would select the "example" profile. The POM would then contain:
...
<properties>
<skip.install>false</skip.install>
...
</properties>
...
<profile>
<id>example</id>
<properties>
<skip.install>false</skip.install>
</properties>
</profile>
...
<plugin>
<artifactId>maven-install-plugin</artifactId>
<version>X.Y</version>
<configuration>
<skip>${skip.install}</skip>
</configuration>
</plugin>
...
Using these POM additions, the default behavior for the install plugin will be to perform its default goal, but if the example profile is selected, then the install plugin will skip its goal.

Using what I learned from the other answers, this was the cleanest result for me.
In my super pom I added a pluginManagement/plugin to disable default-install and default-test phases when the property deployOnly is set.
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-install-plugin</artifactId>
<version>2.5.2</version>
<executions>
<execution>
<id>default-install</id>
<configuration>
<skip>${deployOnly}</skip>
</configuration>
</execution>
<execution>
<id>default-test</id>
<configuration>
<skip>${deployOnly}</skip>
</configuration>
</execution>
</executions>
</plugin>
So on the command line, I can disable install and test phases by adding -DdeployOnly.
mvn clean install #build and test everything
mvn deploy -DdeployOnly #just deploy it

I know that I can use local repo and just set dependencies. But my boss want that our project can build only with public repos and without any our repos.
Are you sure you understood correctly what you boss meant? I interpret the above as "don't install third party libraries in your local repository, use only libraries available in public repositories". This is different from "don't use your local repository" which is basically impossible, that's just not how maven works. I'd try to clarify this point.
Apart from that, I don't get the question which is very confusing (what repo are you talking about? What is the install script doing? Why do you call clean install on libraries? etc).

Extending the other answers, from the future.
Maven plugins have a surprisingly high freedom, how do they run. If they want, they can ignore/override the typical pom.xml settings. Furthermore, also the <configuration><skip>true</skip></configuration> is only a convention, nothing obligates a plugin to follow it, except that most of them is developed so.
My experiments with the recent problem show, that both #Cemo's and #MiloshBoroyevich solution should be utilized, also the plugin requires both to really let us in peace. More concretely, the only working configuration by me was this:
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-install-plugin</artifactId>
<version>2.5.2</version>
<executions>
<execution>
<id>default-install</id>
<phase>none</phase>
</execution>
</executions>
<configuration>
<skip>true</skip>
</configuration>
</plugin>

One of your options is to put the deployment to another module. I.e. have one pom.xml build the artifact and install it to the local repo, and another pom.xml to deploy it. This separation is quite common in larger projects, where the testsuite is sometimes a separate module or even a project, the packaging happens in several stages, etc.
- pom.xml - myProject-root - type=pom
- pom.xml - myProject-artifact - type=jar
- pom.xml - myProject-deploy - type=pom, does the deployment, skips it's own `install` goal

Maven JAR Plugin 3.0.2 Error: You have to use a classifier to attach supplemental artifacts to the project instead of replacing them

Maven JAR plugin (version 3.0.2) keeps throwing the following error, even for a single invocation of the jar goal:
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-jar-plugin:3.0.2:jar (default) on project test: You have to use a classifier to attach supplemental artifacts to the project instead of replacing them. -> [Help 1]
Here's a (minimal?) pom.xml which demonstrates the problem:
<project xmlns="http://maven.apache.org/POM/4.0.0">
<modelVersion>4.0.0</modelVersion>
<groupId>test</groupId>
<artifactId>test</artifactId>
<version>1.0.0-SNAPSHOT</version>
<build>
<plugins>
<plugin>
<artifactId>maven-jar-plugin</artifactId>
<version>3.0.2</version>
<executions>
<execution>
<goals>
<goal>jar</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>
The invocation is just mvn package.
It doesn't seem to matter whether there are any classes/resources at all — the above error message appears anyway.
The problem also appears if two goals are specified (jar and test-jar).
The problem does NOT appear if no goals are specified. But this is not an option, since I really need both jar and test-jar.
According to the documentation, classifier only needs to be specified on multiple invocations of the same goal, and there's a reasonable default for the test-jar goal which I don't intend to change.
Also, the problem doesn't seem to appear on the 2.x line of the JAR plugin.
Did I miss something?
Could anybody please suggest what I am doing wrong?
P.S. The Maven version is 3.3.9.

The Jar Plugin is actually getting executed twice with the configuration:
<plugin>
<artifactId>maven-jar-plugin</artifactId>
<version>3.0.2</version>
<executions>
<execution>
<goals>
<goal>jar</goal>
</goals>
</execution>
</executions>
</plugin>
If you check the logs with such a configuration, you will have something like:
[INFO] --- maven-jar-plugin:3.0.2:jar (default-jar) # test ---
[INFO] Building jar: ...\test\target\test-0.0.1-SNAPSHOT.jar
[INFO]
[INFO] --- maven-jar-plugin:3.0.2:jar (default) # test ---
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
meaning that the plugin was in fact executed twice. What happens, is that the Jar Plugin, in a project that has a packaging of jar has a default execution bound to the package phase. This default execution is the one mentioned in the logs with the ID of default-jar.
When you configured an <execution> in the plugin, you actually configured a new execution, where the jar goal of the plugin is to be invoked. Since the jar goal binds by default to the package phase, that execution is getting executed at that phase, after the default binding inherent to the jar packaging. And since the plugin ran already, it is failing because running it again would actually replace the main artifact already produced during the first run. This error was added in version 3.0.0 of the plugin in MJAR-198, because such a thing happening is very likely a mis-configuration which should be detected early.
As such, the fix is simple: don't have an execution that specifies the goal jar, and let the default one (coming from the jar packaging) do the work. The JAR will still be created, even without the explicit configuration of the jar goal, thanks to the default execution. If you want a test JAR as well, you will still need to configure the plugin to do that with:
<plugin>
<artifactId>maven-jar-plugin</artifactId>
<version>3.0.2</version>
<executions>
<execution>
<goals>
<goal>test-jar</goal>
</goals>
</execution>
</executions>
</plugin>
But note that the goal jar is not specified.

In my case, I have set the execution ID to default-jar, overriding the default execution. Then the error is gone.
<execution>
<id>default-jar</id>
<phase>package</phase>
<goals>
<goal>jar</goal>
</goals>
</execution>

If your logs shows something like:
[INFO] --- maven-jar-plugin:3.0.2:jar (default-jar) # test --
[WARNING] JAR will be empty - no content was marked for inclusion!
Adding a single useless class in src/main/java seems to solve the issue see:
http://maven.40175.n5.nabble.com/quot-mvn-clean-verify-deploy-quot-causes-jar-plugin-to-execute-twice-td5877166.html
Since the above link might be broken as of 2021-09 you might want to try http://mail-archives.apache.org/mod_mbox/maven-users/201608.mbox/thread as an alternative

One reason to have this error may be that the package goal is mistakenly executed twice:
mvn ... package ... package
May happen when the command is built by imperfect scripts :)

A little late but you should add <phase>none</phase> to default-jar execution. this will skip it.
<execution>
<id>default-jar</id>
<phase>none</phase>
</execution>
This will skip the default-jar but others are executed. Make sure you put <phase>package</phase> in the rest of the execution threads.

How to generate separate jar files for application, source, and documentation (for central.sonatype.org)

Sonatype has a repository that I want to deploy a jar file to, and they ask for separate files for application, sources, and javadocs:
Example:
example-application-1.4.7.pom
example-application-1.4.7.jar
example-application-1.4.7-sources.jar
example-application-1.4.7-javadoc.jar
In Scala SBT, I have a command called "package" that generates the jar file for the project, but that only generates "example-application-1.4.7.jar".
Question: What should I do to generate the other two jar files?

In Maven, in order to get the additional -sources and -javadoc artifacts, add to your POM file the following:
<build>
<plugins>
<!-- additional plugin configurations, if any.. -->
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-source-plugin</artifactId>
<version>3.0.0</version>
<executions>
<execution>
<goals>
<goal>jar</goal>
</goals>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-javadoc-plugin</artifactId>
<version>2.10.3</version>
<executions>
<execution>
<goals>
<goal>jar</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>
Note the snippet above:
We are invoking the Maven Source Plugin to create an additional jar files for sources
We are invoking the Maven Javadoc Plugin to create an additional jar files for javadoc
Executing
mvn clean package
You will find these two additional jars in the target folder.
The .pom file instead is generated during the install phase, but it is not placed under the target folder. Basically, it is a copy of your pom.xml file, with a different extension and used by Maven during the dependency mediation process to check which transitive dependencies are required by the concerned artifact.
Executing
mvn clean install
Maven will install the artifact in your local cache (in your machine), under path_to_cache/.m2/repository/your_groupId/your_artifactId/your_version/. In this folder, you will also find the .pom file, which normally you don't need to distribute (it is created automatically by Maven).
Further note: you probably don't want to generate these additional jar files at each and every build, so to speed up normal builds and have them only on demand, you could wrap the snippet above in a Maven profile.
You can achieve this by removing the snippet above from your build section and add a further section at the end of your pom:
<profiles>
<profile>
<id>prepare-distribution</id>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-source-plugin</artifactId>
<version>3.0.0</version>
<executions>
<execution>
<goals>
<goal>jar</goal>
</goals>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-javadoc-plugin</artifactId>
<version>2.10.3</version>
<executions>
<execution>
<goals>
<goal>jar</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>
</profile>
</profiles>
So that normal builds would not create these jars anymore, but when executing the following:
mvn clean install -Pprepare-distribution
You would instead get them back. the -P option is actually activating on demand the profile defined with the id prepare-distribution.
With Maven 3 a default profile already comes as part of the super pom which perform exactly the same actions (sources and javadoc artifact), hence no need to add anything to your existing project. Simply run:
mvn clean install -Prelease-profile
Or, to activate it via a property
mvn clean install -DperformRelease=true
However, as also specified in the super pom, this profile may be removed in future releases (although there since first Maven 3 version till version 3.3.9 so far)
NOTE: The release profile will be removed from future versions of the super POM
The main reason behind this warning is most probably to push for the usage of the Maven Release Plugin, which indirectly makes use of this profile via the useReleaseProfile option of the release:perform goal.
As highlighted by comments, if you are not familiar with maven (especially via console) I would definitely recommend to
Go through the official Maven in 5 minutes documentation for a quick but worthy look.
Play with Maven from the command line, is there where Maven gives you its best. IDE integrations are great, but command line is the real turning point.
Then play with the POM customization above, to get familiar with some concepts and behaviors, first directly as part of your default build, then moved to a profile.
Then, and only then, move to the Maven Release Plugin usage. I recommend it as last step because you would already have acquired more confidence and understanding and see it as less magic and more reasonable approach.

maven upload file per scp

whats the preferred way to upload an artifact via scp to a predefined destination?
i tried using the wagon:upload mojo, but it wont execute atomatically when i defined a "executions" section in my pom like that:
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>wagon-maven-plugin</artifactId>
<version>1.0-beta-3</version>
<executions>
<execution>
<phase>release</phase>
<goals>
<goal>upload</goal>
</goals>
</execution>
</executions>
<configuration>
<fromDir>target/checkout/target</fromDir>
<includes>*.jar</includes>
<url>scpexe://host/dir</url>
<toDir />
<serverId>my id</serverId>
</configuration>
</plugin>
i added the necessary extension wagon-ssh and wagon-ssh-external and it all works fine when i execute wagon:upload but it wont upload the artifact automatically in the release phase.
Is this even the right way to upload artifacts to a website, or should the deploy plugin take care of that?
thanks!

That's because no release phase exists (see Maven Lifecycle Reference)
You probably want phase deploy. And yes, wagon is usually used by the maven deploy plugin (automatically when you execute mvn deploy).

maven yui compression on war:war

I'm trying to automatically compress both CSS and JS using maven and this plugin. I want to compress when the goal war is executed but I'm not figuring how:
<build>
<finalName>${artifactId}-${version}-production</finalName>
<plugins>
<plugin>
<groupId>net.sf.alchim</groupId>
<artifactId>yuicompressor-maven-plugin</artifactId>
<executions>
<execution>
<configuration>
<gzip>true</gzip>
<nosuffix>true</nosuffix>
</configuration>
<goals>
<goal>compress</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>

You need to bind the execution to a phase so it will be executed when you run the war packaging. These are the available phases you can bind to for war packaging.
<plugin>
<groupId>net.sf.alchim</groupId>
<artifactId>yuicompressor-maven-plugin</artifactId>
<executions>
<execution>
<id>compress</id>
<phase>process-resources</phase>
...<!--rest of config is fine-->
Update: Are the js.gz files not being generated or just not included in the war?
One additional thing to check if you're still not seeing the content in the war is that the resources should be under src/main/resources, not src/main/webapp.
The yuicompressor plugin will process the js files in src/main/webapp, but they won't be included in the final war.
Update 2: reread your question after seeing your answer, I'd misread the goal you were running. To avoid running two goals you can do one of these:
Try instead of running the war goal, run install or package, this will invoke the standard lifecycle, and the yuicompressor plugin will be invoked in the process-resources phase.
Alternatively change the phase the yuicompressor goal is bound to in the example above to package so it is activated when you run the war:war goal.

for some weird reason war:war doesn't call the plugin in the phase process-resources: I just added a custom menu on nb 6.7 that call first compile, then war:war