Google App Engine and Maven

I created a small project that I wanted to host somewhere for free. Amazon free tier or Google App Engine? I already have experience with AWS, so I decided to try GAE. It is completely different, of course. And it didn’t start quite well, with some NullPointerExceptions from the eclipse plugin. But ultimately, it worked fine. However, I was a bit confused how to use Maven in a GAE project. By default, everything should go to the /war directory, and that’s not maven’s directory structure. And this post scared me even more – the pom.xml looks appalling. What I ultimately achieved is workable, and the pom remains simple.

• mavenzie your project (m2eclipse). Update project configuration to have everything in place
• In right click > Properties > Google > Web applications have the path pointing to “target/project-0.0.1-SNAPSHOT” (or whatever your assembly folder is), and uncheck the “launch and deploy from this directory”.
• Move everything from “war” to “src/main/webapp”. Parhaps without the jars, which you can add as maven dependencies
• run maven > package, so that the target directory is populated
• Right click > Deploy to Google App Engine – it will ask you for a directory the first time – choose “…/target/project-0.0.1-SNAPSHOT” again (this is absolute path). It will remember this decision, but don’t commit the .settings/com.google.gdt.eclipse.core.prefs, because it now contains an absolute path

That way everything works fine. Before each deploy you should make a maven build, but that’s not that bad (well, generally speaking, it is bad, but you don’t have hot-deploy here anyway. And my build is really quick. If I had a huge project with a very long build, I wouldn’t go for GAE, but that’s just my opinion)