This is a Heroku Buildpack for running a Minecraft server in a dyno.

Create a free ngrok account and copy your Auth token. Then create a new Git project with a eula.txt file:

$ echo 'eula=true' > eula.txt
$ git init
$ git add eula.txt
$ git commit -m "first commit"

Then, install the Heroku toolbelt. Create a Heroku app, set your ngrok token, and push:

$ heroku create
$ heroku buildpacks:add heroku/jvm
$ heroku buildpacks:add https://github.com/jkutner/heroku-buildpack-minecraft
$ heroku config:set NGROK_API_TOKEN="xxxxx"
$ git push heroku master

Finally, open the app:

$ heroku open

This will display the ngrok logs, which will contain the name of the server (really it's a proxy, but whatever):

Server available at: 0.tcp.ngrok.io:17003

Copy the 0.tcp.ngrok.io:17003 part, and paste it into your local Minecraft app as the server name.

The Heroku filesystem is ephemeral, which means files written to the file system will be destroyed when the server is restarted.

Minecraft keeps all of the data for the server in flat files on the file system. Thus, if you want to keep you world, you'll need to sync it to S3.

First, create an AWS account and an S3 bucket. Then configure the bucket and your AWS keys like this:

$ heroku config:set AWS_BUCKET=your-bucket-name
$ heroku config:set AWS_ACCESS_KEY=xxx
$ heroku config:set AWS_SECRET_KEY=xxx

The buildpack will sync your world to the bucket every 60 seconds, but this is configurable by setting the AWS_SYNC_INTERVAL config var.

You can customize ngrok by setting the NGROK_OPTS config variable. For example:

$ heroku config:set NGROK_OPTS="-subdomain=my-subdomain"

You can choose the Minecraft version by setting the MINECRAFT_VERSION like so:

$ heroku config:set MINECRAFT_VERSION="1.8.3"

You can also configure the server properties by creating a server.properties file in your project and adding it to Git. This is how you would set things like Creative mode and Hardcore difficulty. The various options available are described on the Minecraft Wiki.

You can add files such as banned-players.json, banned-ips.json, ops.json, whitelist.json to your Git repository and the Minecraft server will pick them up.