Deploy Dropwizard on Google AppEngine - google-app-engine

Question

I have been trying to find a way to deploy a Dropwizard app on Google AppEngine, but I haven't found anything so far.
Judging by this question (and answer) I think it might not be possible.
I would like to be sure about that, and If it does work, I'd like to learn how.
There is a dropwizard fork called warwizard which apparently lets you create war files from your dropwizard code, but it has not been touched for over 6 months, which would likely make it difficult to work with using the dropwizard docs.

Answer 1

Dropwizard is just Jersey+Jackson+Jetty bundled together nicely. Jetty and App Engine won't get along (that is, App Engine is already running Jetty, so it doesn't want the application to provide its own).
You're probably best off using Jersey and Jackson without Dropwizard tying them together: http://blog.iparissa.com/googles-app-engine-java/google-app-engine-jax-rs-jersey/ & http://www.cowtowncoder.com/blog/archives/2009/11/entry_338.html

Answer 2

You can however, run Dropwizard on Google Compute Engine. Which is basically just linux VMs provided by Google, with access to their APIs if needed.
I manged to get my Dropwizard instance working by doing the following on GCE:
Install Java
sudo apt-get install java7-runtime-headless
Open firewall ports:
gcutil addfirewall rest --description="http" --allowed="tcp:8080
gcutil addfirewall admin --description="admin" --allowed="tcp:8081"
Copy file to GCE
gcutil --project={project-id} push {instance-name} {local-file} {remote-target-path}
Run your app
java -jar your-app.jar server your-config.yml
EDIT: there is also another alternative called wiztowar https://github.com/twilio/wiztowar which supports DW 0.6.2 only.

Answer 3

I've been trying to solve this issue for the past two month. Here are my findings:
1- Yes, you can deploy Dropwizard as a WAR file. You need to use some hacks like Wizard in a box or WizToWar
2- No! You can't deploy that WAR file on AppEngine standard environment.
Why?
The main issue is that AppEngine is using servlet-api v2.5 (which is more than 10 years old!) and has no plan to upgrade to servlet-api v3 or higher. Dropwizard on the other hand require servlet-api v3 or higher.
BUT wait! there is another option
You can deploy Dropwizard on App Engine Flexible Environment
App Engine Flex is still in beta, but I've heard it will be available for public usage in Q1 2017. If you want to use it now, you have to ask for that to be enabled for you.
How do you deploy on App Engine Flex?
-> I've put all the steps on doing that in a blog post here:
Deploying Dropwizard on App Engine Flex