Develop Reference

Publish from internal nexus to maven central

I have an internal nexus that contains all the artifacts that we build.
Once an artifact is tested, I want to take the sane artifact and deploy it to Maven Central without rebuilding it.
I know that I might be able to do that using mvn deploy:deploy-file but it seems complicated.
Is there an easy way to do it?
Note: due to historical reasons,we don't use SNAPSHOT versions. All versions are in the style of artifact-name-X.Y.Z.jar were X.Y.Z is the version number. We have an internal tool that can be queried for sanity.

I've ended using an approach similar to what they have in here:
https://central.sonatype.org/pages/manual-staging-bundle-creation-and-deployment.html
So, if I had the following files:
ossrh-test-1.2.pom
ossrh-test-1.2.jar
ossrh-test-1.2-javadoc.jar
ossrh-test-1.2-sources.jar
I've invoked this command for the JAR:
mvn gpg:sign-and-deploy-file -Durl=https://oss.sonatype.org/service/local/staging/deploy/maven2/ -DrepositoryId=ossrh -DpomFile=ossrh-test-1.2.pom -Dfile=ossrh-test-1.2.jar
And the following commands for the sources and JavaDocs:
mvn gpg:sign-and-deploy-file -Durl=https://oss.sonatype.org/service/local/staging/deploy/maven2/ -DrepositoryId=ossrh -DpomFile=ossrh-test-1.2.pom -Dfile=ossrh-test-1.2-sources.jar -Dclassifier=sources
mvn gpg:sign-and-deploy-file -Durl=https://oss.sonatype.org/service/local/staging/deploy/maven2/ -DrepositoryId=ossrh -DpomFile=ossrh-test-1.2.pom -Dfile=ossrh-test-1.2-javadoc.jar -Dclassifier=javadoc
Last but not least, since I had to create fake sources and javadoc jars I've just taken a jar, unzipped it, put a readme file inside of it instead of the old content, updated the manifest and zipped it again. Then I've uploaded it as my fake sources/javadoc jars.

Let me assume you have not only x.y.z version of binaries, but also scm tag for this version.
If so, you can give a try to the following CI job:
<scm> checkout <YOUR TAG>
<scm> clean -d -x -f
mvn maven-dependency-plugin:get -Pcustom-deployment -DexecutionId=resolve-sane-binaries
mvn maven-deploy-plugin:deploy -Pcustom-deployment -DexecutionId=deploy-sane-binaries
with profile in your pom.xml:
<profiles>
<profile>
<id>custom-deployment</id>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-dependency-plugin</artifactId>
<version>3.1.2</version>
<executions>
<execution>
<id>resolve-sane-binaries</id>
<goals>
<goal>get</goal>
</goals>
<configuration>
<artifactItems>
<artifactItem>
<groupId>${project.groupId}</groupId>
<artifactId>${project.artifactId}</artifactId>
<version>${project.version}</version>
<type>${project.packaging}</type>
<outputDirectory>${project.build.directory}</outputDirectory>
<destFileName>${project.build.finalName}</destFileName>
</artifactItem>
...
</artifactItems>
...
</configuration>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-deploy-plugin</artifactId>
<version>2.8.2</version>
<executions>
<execution>
<id>deploy-sane-binaries</id>
<goals>
<goal>deploy-file</goal>
</goals>
<configuration>
...
</configuration>
</execution>
<executions>
<plugin>
</plugins>
It's just an idea, not a code I've really tested. But hope it'll help.

Getting maven to execute a program and store the output into a property that can be used in a .jar manifest

I would like to execute git describe as part of a maven build and use the resulting output in the manifest for building a .jar package.
I know how to do this in ant via the <exec> task with outputproperty to an ant property variable, but I have very little experience with Maven and don't even know where to look.
Is this possible?
I found this in a sample pom.xml file so adding something to the manifest looks pretty easy:
<project>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-jar-plugin</artifactId>
<version>2.6</version>
<configuration>
<archive>
<manifest>
<addClasspath>true</addClasspath>
<mainClass>my.class.here.Myclass</mainClass>
<classpathLayoutType>custom</classpathLayoutType>
<customClasspathLayout>lib/$${artifact.artifactId}-$${artifact.version}$${dashClassifier?}.$${artifact.extension}</customClasspathLayout>
</manifest>
</archive>
</configuration>
</plugin>
</plugins>
</build>
</project>
Not sure how to capture command execution though.

Here is a suggested approach:
Use the Exec Maven Plugin for launching your git commands and write to a properties file (name=value pattern, if possible)
Use the Properties Maven Plugin to load the configuration
The configuration loaded can then be used as properties in your POM. We are basically dynamically creating properties of our build. To do so (to use these properties), the steps above must be executed as early as possible in the build flow (i.e. validate or initialize phase).
Below an example of flow, just tested and work perfectly (on Windows machine):
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.sample</groupId>
<artifactId>generation</artifactId>
<version>0.0.1-SNAPSHOT</version>
<build>
<plugins>
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>exec-maven-plugin</artifactId>
<version>1.1</version>
<executions>
<execution>
<id>retrieve-config</id>
<phase>validate</phase>
<goals>
<goal>exec</goal>
</goals>
</execution>
</executions>
<configuration>
<executable>echo</executable>
<arguments>
<argument>jar.name=from-exec</argument>
<argument>></argument>
<argument>config.properties</argument>
</arguments>
<workingDirectory>${basedir}/src/main/resources/</workingDirectory>
</configuration>
</plugin>
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>properties-maven-plugin</artifactId>
<version>1.0-alpha-2</version>
<executions>
<execution>
<id>read-properties</id>
<phase>initialize</phase>
<goals>
<goal>read-project-properties</goal>
</goals>
<configuration>
<files>
<file>${basedir}/src/main/resources/config.properties</file>
</files>
</configuration>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-jar-plugin</artifactId>
<version>2.4</version>
<configuration>
<finalName>${jar.name}</finalName>
</configuration>
</plugin>
</plugins>
</build>
</project>
Basically, the exec plugin attached to the validate phase will be executed at the beginning of the build, writing to a config.properties file (via the echo command) the content jar.name=from-exec.
Then the properties plugin attached to the initialize phase will read that config.properties file and load the properties to be used as part of the build.
Then, as an example, the jar plugin will use that property as part of its configuration (the <finalName>${jar.name}</finalName> part).
Running mvn clean package, you will find the from-exec.jar file in the target folder.
If you can't get a way of having the result of git describe as name=value pattern, you can (worst case) have two Exec Maven Plugin executions, the first writing to the file the property name and the equals character (i.e. via an echo), the second (git describe) appending to the file the property value.

There is a Maven plugin here https://github.com/ktoso/maven-git-commit-id-plugin that will do what you want.
If you hook into your build it will generate a Maven variable named ${git.commit.id.describe} that you can then use Maven's resource filtering to dynamically modify your manifest.

Building on what #A_Di-Matteo said, you can get the git tag into the properties file like this
In the maven exec plugin.
<execution>
<id>set-git-tag</id>
<phase>validate</phase>
<goals>
<goal>exec</goal>
</goals>
<configuration>
<executable>bash</executable>
<arguments>
<argument>-c</argument>
<argument>echo git.tag=`git describe --always --dirty=-modified`</argument>
<argument>></argument>
<argument>config.properties</argument>
</arguments>
<workingDirectory>${basedir}/src/main/resources/</workingDirectory>
</configuration>
</execution>
You can also append to an existing file like so
<execution>
<id>set-git-tag</id>
<phase>validate</phase>
<goals>
<goal>exec</goal>
</goals>
<configuration>
<executable>bash</executable>
<arguments>
<argument>-c</argument>
<argument>echo git.tag=`git describe --always --dirty=-modified`</argument>
<argument>>></argument>
<argument>${basedir}/src/main/resources/config.properties</argument>
</arguments>
</configuration>
</execution>
The limitation here is that it requires bash.

Maven deploy jar with dependencies to repo

I can deploy a jar by using the following in my pom.xml and running mvn deploy:
<distributionManagement>
<repository>
<id>releases</id>
<url>http://${host}:8081/nexus/content/repositories/releases</url>
</repository>
<snapshotRepository>
<id>snapshots</id>
<name>Internal Snapshots</name>
<url>http://${host}:8081/nexus/content/repositories/snapshots</url>
</snapshotRepository>
</distributionManagement>
And I can build an executable jar-with-dependencies using the following:
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<executions>
<execution>
<id>create-executable-jar</id>
<phase>deploy</phase>
<goals>
<goal>single</goal>
</goals>
<configuration>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
<archive>
<manifest>
<mainClass>my.company.app.Main</mainClass>
</manifest>
</archive>
</configuration>
</execution>
</executions>
</plugin>
Problem is I don't know how to stitch these together to deploy the executable jar to my Maven repo. I don't really know if this is accomplished by a new plugin or by adding a goal or other step to the existing assembly plugin.

If you bind the assembly to the packaging phase, it will install in your repository both the "regular" jar and the with-dependencies jar when you do a build:
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<configuration>
<archive>
<manifest>
<mainClass>my.company.app.Main</mainClass>
</manifest>
</archive>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
</configuration>
<executions>
<execution>
<id>make-assembly</id> <!-- this is used for inheritance merges -->
<phase>package</phase> <!-- bind to the packaging phase -->
<goals>
<goal>single</goal>
</goals>
</execution>
</executions>
</plugin>
Then simply run mvn clean install deploy to upload both jars to your repository.

In order to build a (so-called) Über JAR and deploy it using maven, you could also use the shade plugin. The following code is taken from their website but I've made one or two projects using this feature.
<project>
...
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-shade-plugin</artifactId>
<version>2.0</version>
<executions>
<execution>
<phase>package</phase>
<goals>
<goal>shade</goal>
</goals>
<configuration>
<shadedArtifactAttached>true</shadedArtifactAttached>
<shadedClassifierName>jackofall</shadedClassifierName> <!-- Any name that makes sense -->
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
...
</project>
In this configuration you get the Über JAR as one deployment besides the normal JAR. The user of your JAR can then decide to pull the all-in-one package or the JAR with dependencies based on the classifier.
I'll usually use the shade plugin to build Über JARs (or modify the JAR in a way) and use the assembly plugin to build things like installation packages (containing the JAR and possibly other things). I am unsure what the intended goals of the single plugins are however.

The following worked. I'm going to leave this question open a bit because I'm not positive this is best practice, but working is something.
Problems I notice are that I made up the ID name and I don't know if this is usual practice and that I have to hard code the jar name; it isn't inferred from anything else.
<plugin>
<artifactId>maven-deploy-plugin</artifactId>
<version>2.7</version>
<executions>
<execution>
<id>deploy-executable</id>
<goals>
<goal>deploy-file</goal>
</goals>
<configuration>
<file>target/Monitoring-Client-1.0-SNAPSHOT-jar-with-dependencies.jar</file>
</configuration>
</execution>
</executions>
</plugin>

Essentially my difficulty doing this revealed the fact that my pom.xml was way off the rails already. Everything would have snapped into place on its own. I was formerly doing:
Save all the dependencies into a lib folder
Build a jar with a classpath slurping up that lib folder
Use the assembly plugin to make another deployable jar
I think there were several reasons this sort of made sense along the way, especially when my libraries were not well-factored from my applications.
However by deleting 1 and 2 all that is needed is the distributionManagement section and the deploy phase works automagically. So all in all this is an amazing case of literally adding functionality by deleting large swathes of code.

First you shouldn't do the creation of the ueber jar in the deploy phase it's better to do this in the package phase. Furthermore the created jar file is usually automatically attached to your artifact and will be transfered to the remote repository (in your case Nexus). You can check this if you simply try to do a mvn install and take a look at the output if the created jar is installed into the local repository.
To deploy the results into nexus you need to call mvn deploy.

What is the best way to avoid maven-jar?

I am using a different plugin (ant4eclipse) to jar my files. What is the best way to avoid the maven-jar plugin from executing?
I tried to remove the <plugin>maven-jar-plugin</plugin>
I tried to <exclude> ** / * < / exclude>
I tried to <skip>true</skip>
None worked

In Maven 3.0.x (I tried 3.0.2) you can disable maven-jar-plugin by binding the default-jar execution to a nonexistent phase, as #bmargulies suggested. Unfortunately that doesn't work in 2.2.1, but you can prevent it from interfering with your own jar by setting an alternative <finalName> and <classifier> for the default-jar execution; it will still create a jar, but it will be set as a secondary artifact for the project and won't overwrite the one you've created. Here's an example that should work in both Maven 2 and Maven 3:
<project>
<modelVersion>4.0.0</modelVersion>
<groupId>test</groupId>
<artifactId>test</artifactId>
<version>0.1-SNAPSHOT</version>
<build>
<plugins>
<plugin>
<artifactId>maven-jar-plugin</artifactId>
<executions>
<execution>
<id>default-jar</id>
<phase>none</phase>
<configuration>
<finalName>unwanted</finalName>
<classifier>unwanted</classifier>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>
Once you've disabled maven-jar-plugin, maven-install-plugin may give you trouble too. In Maven 3 it can be disabled the same as maven-jar-plugin: bind default-install to a nonexistent phase. However, in Maven 2 maven-install-plugin requires that the target/classes directory exist, and it will install the dummy jar when there isn't a primary artifact present.

This should do the trick - notice the use of <id>default-jar</id> and <phase/>.
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-jar-plugin</artifactId>
<version>2.4</version>
<executions>
<execution>
<id>default-jar</id>
<phase/>
</execution>
</executions>
</plugin>
</plugins>
</build>

In my case, I only wanted to disable the jar plugin because the jar was empty. You can use the skipIfEmpty option in the plugin configuration
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-jar-plugin</artifactId>
<version>3.0.2</version>
<configuration>
<skipIfEmpty>true</skipIfEmpty>
</configuration>
</plugin>

What happens if you declare this?
<packaging>pom</packaging>
Even if it does what you're looking for, be careful. I'm not sure if there could be negative side effects -- such as other maven projects that depend on your jar not being able to locate it.

Using maven 3.3.9, the following worked for me:
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-jar-plugin</artifactId>
<version>3.1.2</version>
<executions>
<execution>
<id>default-jar</id>
<phase>none</phase>
<configuration>
<finalName>unwanted</finalName>
<classifier>unwanted</classifier>
</configuration>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-install-plugin</artifactId>
<version>3.0.0-M1</version>
<configuration>
<skip>true</skip>
</configuration>
</plugin>
So in case of the maven-jar-plugin, I bound it to a non-existent phase. For the maven-install-plugin, I used the "skip" configuration parameter. The documentation about it says: "Set this to true to bypass artifact installation. Use this for artifacts that does not need to be installed in the local repository."

Explicitly bind the jar plugin to a phase that doesn't exist.

As other's have said, it's not possible to turn it off, other than using <packaging>pom</packaging>, which turns everything off and is probably not what you want.
Even though it will generate twice, a working solution is to bind your jar process to the package phase, as that is guaranteed to run after the default. By overwriting the same JAR file, you'll find that yours is used wherever the original would have been.

I am using a different plugin to jar my files. What is the best way to avoid the maven-jar plugin from executing?
First, the jar:jar goal is bound by default on the package phase for a project with a packaging of type jar. Second, there is no way to unbind a plugin bound to a phase. So, if you are using another plugin(?), either accept to produce 2 JARs or change the packaging (but I don't think this will work well).

<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-jar-plugin</artifactId>
<configuration>
<skip>true</skip>
</configuration>
</plugin>

Make Maven to copy dependencies into target/lib

How do I get my project's runtime dependencies copied into the target/lib folder?
As it is right now, after mvn clean install the target folder contains only my project's jar, but none of the runtime dependencies.

This works for me:
<project>
...
<profiles>
<profile>
<id>qa</id>
<build>
<plugins>
<plugin>
<artifactId>maven-dependency-plugin</artifactId>
<executions>
<execution>
<phase>install</phase>
<goals>
<goal>copy-dependencies</goal>
</goals>
<configuration>
<outputDirectory>${project.build.directory}/lib</outputDirectory>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
</profile>
</profiles>
</project>

mvn install dependency:copy-dependencies
Works for me with dependencies directory created in target folder. Like it!

The best approach depends on what you want to do:
If you want to bundle your dependencies into a WAR or EAR file, then simply set the packaging type of your project to EAR or WAR. Maven will bundle the dependencies into the right location.
If you want to create a JAR file that includes your code along with all your dependencies, then use the assembly plugin with the jar-with-dependencies descriptor. Maven will generate a complete JAR file with all your classes plus the classes from any dependencies.
If you want to simply pull your dependencies into the target directory interactively, then use the dependency plugin to copy your files in.
If you want to pull in the dependencies for some other type of processing, then you will probably need to generate your own plugin. There are APIs to get the list of dependencies, and their location on disk. You will have to take it from there...

Take a look at the Maven dependency plugin, specifically, the dependency:copy-dependencies goal. Take a look at the example under the heading The dependency:copy-dependencies mojo. Set the outputDirectory configuration property to ${basedir}/target/lib (I believe, you'll have to test).
Hope this helps.

All you need is the following snippet inside pom.xml's build/plugins:
<plugin>
<artifactId>maven-dependency-plugin</artifactId>
<executions>
<execution>
<phase>prepare-package</phase>
<goals>
<goal>copy-dependencies</goal>
</goals>
<configuration>
<outputDirectory>${project.build.directory}/lib</outputDirectory>
</configuration>
</execution>
</executions>
</plugin>
The above will run in the package phase when you run
mvn clean package
And the dependencies will be copied to the outputDirectory specified in the snippet, i.e. lib in this case.
If you only want to do that occasionally, then no changes to pom.xml are required. Simply run the following:
mvn clean package dependency:copy-dependencies
To override the default location, which is ${project.build.directory}/dependencies, add a System property named outputDirectory, i.e.
-DoutputDirectory=${project.build.directory}/lib

If you want to do this on an occasional basis (and thus don't want to change your POM), try this command-line:
mvn dependency:copy-dependencies -DoutputDirectory=${project.build.directory}/lib
If you omit the last argument, the dependences are placed in target/dependencies.

A simple and elegant solution for the case where one needs to copy the dependencies to a target directory without using any other phases of maven (I found this very useful when working with Vaadin).
Complete pom example:
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>groupId</groupId>
<artifactId>artifactId</artifactId>
<version>1.0</version>
<dependencies>
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis-spring</artifactId>
<version>1.1.1</version>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<artifactId>maven-dependency-plugin</artifactId>
<executions>
<execution>
<phase>process-sources</phase>
<goals>
<goal>copy-dependencies</goal>
</goals>
<configuration>
<outputDirectory>${targetdirectory}</outputDirectory>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>
Then run mvn process-sources
The jar file dependencies can be found in /target/dependency

Try something like this:
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-jar-plugin</artifactId>
<version>2.4</version>
<configuration>
<archive>
<manifest>
<addClasspath>true</addClasspath>
<classpathPrefix>lib/</classpathPrefix>
<mainClass>MainClass</mainClass>
</manifest>
</archive>
</configuration>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-dependency-plugin</artifactId>
<version>2.4</version>
<executions>
<execution>
<id>copy</id>
<phase>install</phase>
<goals>
<goal>copy-dependencies</goal>
</goals>
<configuration>
<outputDirectory>
${project.build.directory}/lib
</outputDirectory>
</configuration>
</execution>
</executions>
</plugin>

supposing
you don't want to alter the pom.xml
you don't want test scoped (e.g. junit.jar) or provided dependencies (e.g. wlfullclient.jar)
here ist what worked for me:
mvn install dependency:copy-dependencies -DincludeScope=runtime -DoutputDirectory=target/lib

If you want to deliver a bundle of your application jar, together with all its dependencies and some scripts to invoke the MainClass, look at the appassembler-maven-plugin.
The following configuration will generate scripts for Window and Linux to launch the application (with a generated path referencing all the dependency jars, download all dependencies (into a lib folder below target/appassembler). The assembly plugin can then be used to package the whole appassembler directory to a zip which is installed/deployed along with the jar to the repository.
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>appassembler-maven-plugin</artifactId>
<version>1.0</version>
<executions>
<execution>
<id>generate-jsw-scripts</id>
<phase>package</phase>
<goals>
<goal>generate-daemons</goal>
</goals>
<configuration>
<!--declare the JSW config -->
<daemons>
<daemon>
<id>myApp</id>
<mainClass>name.seller.rich.MyMainClass</mainClass>
<commandLineArguments>
<commandLineArgument>start</commandLineArgument>
</commandLineArguments>
<platforms>
<platform>jsw</platform>
</platforms>
</daemon>
</daemons>
<target>${project.build.directory}/appassembler</target>
</configuration>
</execution>
<execution>
<id>assemble-standalone</id>
<phase>integration-test</phase>
<goals>
<goal>assemble</goal>
</goals>
<configuration>
<programs>
<program>
<mainClass>name.seller.rich.MyMainClass</mainClass>
<!-- the name of the bat/sh files to be generated -->
<name>mymain</name>
</program>
</programs>
<platforms>
<platform>windows</platform>
<platform>unix</platform>
</platforms>
<repositoryLayout>flat</repositoryLayout>
<repositoryName>lib</repositoryName>
</configuration>
</execution>
</executions>
</plugin>
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<version>2.2-beta-4</version>
<executions>
<execution>
<phase>integration-test</phase>
<goals>
<goal>single</goal>
</goals>
<configuration>
<descriptors>
<descriptor>src/main/assembly/archive.xml</descriptor>
</descriptors>
</configuration>
</execution>
</executions>
</plugin>
The assembly descriptor (in src/main/assembly) to package the direcotry as a zip would be:
<assembly>
<id>archive</id>
<formats>
<format>zip</format>
</formats>
<fileSets>
<fileSet>
<directory>${project.build.directory}/appassembler</directory>
<outputDirectory>/</outputDirectory>
</fileSet>
</fileSets>
</assembly>

If you make your project a war or ear type maven will copy the dependencies.

It's a heavy solution for embedding heavy dependencies, but Maven's Assembly Plugin does the trick for me.
#Rich Seller's answer should work, although for simpler cases you should only need this excerpt from the usage guide:
<project>
<build>
<plugins>
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<version>2.2.2</version>
<configuration>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
</configuration>
</plugin>
</plugins>
</build>
</project>

You can use the the Shade Plugin to create an uber jar in which you can bundle all your 3rd party dependencies.

Just to spell out what has already been said in brief. I wanted to create an executable JAR file that included my dependencies along with my code. This worked for me:
(1) In the pom, under <build><plugins>, I included:
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<version>2.2-beta-5</version>
<configuration>
<archive>
<manifest>
<mainClass>dk.certifikat.oces2.some.package.MyMainClass</mainClass>
</manifest>
</archive>
<descriptorRefs>
<descriptorRef>jar-with-dependencies</descriptorRef>
</descriptorRefs>
</configuration>
</plugin>
(2) Running mvn compile assembly:assembly produced the desired my-project-0.1-SNAPSHOT-jar-with-dependencies.jar in the project's target directory.
(3) I ran the JAR with java -jar my-project-0.1-SNAPSHOT-jar-with-dependencies.jar

If you're having problems related to dependencies not appearing in the WEB-INF/lib file when running on a Tomcat server in Eclipse, take a look at this:
ClassNotFoundException DispatcherServlet when launching Tomcat (Maven dependencies not copied to wtpwebapps)
You simply had to add the Maven Dependencies in Project Properties > Deployment Assembly.

You could place a settings.xml file in your project directory with a basic config like this:
<?xml version="1.0" encoding="UTF-8"?>
<settings xmlns="http://maven.apache.org/SETTINGS/1.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/SETTINGS/1.0.0 https://maven.apache.org/xsd/settings-1.0.0.xsd">
<localRepository>.m2/repository</localRepository>
<interactiveMode/>
<offline/>
<pluginGroups/>
<servers/>
<mirrors/>
<proxies/>
<profiles/>
<activeProfiles/>
</settings>
More information on these settings can be found in the official Maven docs.
Note that the path is resolved relative to the directory where the actual settings file resides in unless you enter an absolute path.
When you execute maven commands you can use the settings file as follows:
mvn -s settings.xml clean install
Side note: I use this in my GitLab CI/CD pipeline in order to being able to cache the maven repository for several jobs so that the dependencies don't need to be downloaded for every job execution. GitLab can only cache files or directories from your project directory and therefore I reference a directory wihtin my project directory.