Question

We’re using exec-maven-plugin to run RequireJS’s optimizer (r.js) under Node.js (because it’s a lot faster than Rhino):

<plugin>
    <groupId>org.codehaus.mojo</groupId>
    <artifactId>exec-maven-plugin</artifactId>
    <version>1.2</version>
    <executions>
        <execution>
            <id>compile-js</id>
            <phase>prepare-package</phase>
            <goals>
                <goal>exec</goal>
            </goals>
            <configuration>
                <executable>${node.executable}</executable>
                <arguments>
                    <argument>${project.build.directory}/dependency/requirejs/r.js</argument>
                    <argument>-o</argument>
                </arguments>
            </configuration>
        </execution>
    </executions>
</plugin>

The issue is, whenever there’s any issue during compilation, the error messages that r.js is supposed to blurt out are not shown in Maven’s console output. What I do to troubleshoot is, I rerun the Maven command with the -X flag to get debug output so that exec-maven-plugin outputs the actual command being executed. It’s something like:

project-root/target/dependency/node/node \
    project-root/target/dependency/requirejs/r.js \
    -o src/main/webapp/app.build.json

When I run the command manually from the command line, I then get the actual compilation errors in the console and then proceed to fixing them.

I’ve experimented with redirecting stderr to stdout with 2>&1 to no avail (on Windows) because I couldn’t immediately find a way to make exec-maven-plugin like the redirection bit as an argument. I didn’t pursue that route too far because it’s just a wild guess that this is a stderr/stdout issue — it could be, but I’m merely speculating.

Any pointers to as to what may be happening, or any suggestions for further diagnostic steps that I can take? Please remember there are multiple moving parts in this problem: Maven, exec-maven-plugin, Node.js, r.js, and one tired head.

P.S. I’m considering giving requirejs-maven-plugin a shot as a last resort because the project timeline doesn’t allow me to do a complete overhaul of the POM right now. I’m trying to see if there’s anything I can do with the current setup.

Answer 1

How about wrapping the call to node.js and r.js in a script, that you then call from the maven-exec plugin?

From a look at r.js, it seems to use console.log for it’s output. Maybe running it from a shell script will allow you to catch the output, pipe it into a file, regex for an errors, etc.

Depending on the OS, this might be easy to do.