Is it possible to compile grunt project from maven?

Yes, using the frontend-maven-plugin, you can compile Grunt projects via Maven (found via the NodeJS mailing list).

As the documentation points out, the plugin has the following features:

• Let you keep your frontend and backend builds as separate as possible, by reducing the amount of interaction between them to the bare minimum; using only 1 plugin.
• Let you use Node.js and its libraries in your build process without installing Node/NPM globally for your build system
• Let you ensure that the version of Node and NPM being run is the same in every build environment

I've walked through the code and it's fairly simple. Thank goodness someone finally put this together; it's an elegant solution. The repository includes an example that uses a regular Gruntfile.js to invoke jshint analysis.

UPDATE 2014-09-19: This is no longer the most accurate answer - please take a look at some of the other answers below. It was accurate at the time when I answered the question, but there seems to have been a good deal of progress in this area since then.

I'm afraid you're out of luck. Grunt is built using node and needs to be installed using npm. You might be able to copy an existing installation of Grunt from another machine if you don't want to use npm, but will still use the grunt executable and all of its dependencies on your build server.

In addition to that, many of the Grunt tasks are implemented as Node.js modules, and you will have to install them as well. Again, you might be able to copy them from another server, where you've done the Node.js/Grunt installation, but at one point, you have to do it.

For running Grunt from Maven, your best bet is to use the Maven exec plugin and then execute the grunt executable from there.

As an alternative, there are several Maven plugins that allow you to do things similar to Grunt in a Java-based fashion. They require additional configuration not compatible with Grunt, so YMMV. One that I've used in the past is http://code.google.com/p/wro4j/, which comes with a Maven plugin as well: http://code.google.com/p/wro4j/wiki/MavenPlugin

Any particular reason why you can't install Node.js on your build server?

You can use grunt-maven-plugin. It allows you to easily integrate Grunt tasks into Maven build process. No dirty hacks.

This is what I use in my current project and it works just perfect.

Finally I ended up with this (which is close enough but doesn't solve the problem):

<plugin>
<groupId>org.mule.tools.javascript</groupId>
<artifactId>npm-maven-plugin</artifactId>
<version>1.0</version>
<executions>
    <execution>
        <phase>generate-resources</phase>
            <goals>
                <goal>fetch-modules</goal>
            </goals>
            <configuration>
                <packages>
                    <package>grunt-cli:0.1.6</package>
                </packages>
            </configuration>
        </execution>
    </executions>
</plugin>

that installs locally the grunt-cli, but if I don't have installed node.js it's worthless. Although I try to install node.js locally there's the need to have installed python, g++ and make. So I'll go with the KISS solution: install grunt in the build server.

References:
https://github.com/mulesoft/npm-maven-plugin
https://github.com/joyent/node/wiki/Installing-Node.js-via-package-manager
https://github.com/mcheely/requirejs-maven-plugin

You might want to checkout http://jhipster.github.io/ : it's a Yeoman generator, that generates an application which has Maven, Grunt and Bower all working together.

It's a bit like your third option, but everything is configured for you, which isn't that easy. It's also generating the basic AngularJS and Java REST services for you

The first problem is that Maven is Java, but Grunt.js runs on the Node.js runtime. The easiest integration I ever achieved between the two involved the maven-exec-plugin. The maven-exec-plugin is capable of executing .sh/.bat/.cmd scripts, whichever are native to the OS you are using. So during a Maven build I would have the maven-exec-plugin execute a script named optimize-js.sh, for example, which would simply do something like “grunt release –force”, or whatever. The scripts can be made to do whatever. The important thing is to configure the maven-exec-plugin to execute them in the correct working directory. Of course, “grunt” and “node” need to be executable from the command-line.

If the problem is installing NodeJS on the Jenkins machine then you can use the NodeJS Jenkins plugin.

https://wiki.jenkins-ci.org/display/JENKINS/NodeJS+Plugin

We're not using it with Maven (yet) but we've got grunt running.