Easy MCS

Docker image that runs your minecraft server so that people can join with no port forwarding required, completely agnostic of what kind of server you are using. There is also an optional built-in backup system (also agnostic of server type).

Quick Start

1. sign up for ngrok and grab your auth token
2. create a directory including your server directory, renamed to server, and a file named .env in the format:

NGROK_AUTHTOKEN="your ngrok auth token"
START_COMMAND="the command to start your server (from within the server's directory) e.g. java -Xmx4G -Xms2G -jar server.jar nogui"

3. Install docker if it's not already installed (see the docs) and run the daemon
4. download this docker compose file
5. run docker compose up -d && docker attach mcs
6. grab the ip address that got printed out and send it to anyone who wants to join!

You can run server commands directly through the standard in. Use /stop to close the server.

There are some limits on ngrok's free tier

Backups (Optional)

This images provides the option to backup to, and load from backups in AWS S3.

To setup backups, first do the following in AWS:

1. Create an S3 Bucket. Zip your server folder and upload it into backup.zip within the bucket
2. Create an IAM Policy that only allows GetObject and PutObject, and only on the S3 Bucket for your backups
3. Create IAM User for the policy. Generate credentials for this user.

Add the following to your .env file:

BACKUP_FREQUENCY="integer of how often to run backups, in milliseconds"
S3_BUCKET_NAME="name of the S3 bucket you created"
S3_REGION="region of your S3 bucket"
AWS_ACCESS_KEY_ID="from generated credentials"
AWS_SECRET_ACCESS_KEY="from generated credentials"
USE_BACKUP="optional, if set (to anything other than empty string), downloads the backup from S3 and uses that instead of a local server directory"

Versatility Options

If you'd like to use this image in a more versatile fashion, e.g. without using an env file, on a different port, different terminal configurations, etc. you can do so with no trouble as long as the following are true:

1. all necessary and desired environment variables are set, e.g. with the -e flag with docker run
2. either your local server directory is mapped as a volume into /server in the container, or the USE_BACKUP environment variable is set
3. there is a port mapping to 25565 in the container

Recommended:

1. leave the standard in of the container open
2. don't use the -t flag or tty: true (compose). The image is not built to handle terminal controls.
3. run the image as a daemon, then attach to its standard in, like in the quick start. This will allow you to run commands in the server.

Experiments

One cool idea is to run this docker image in a GitHub Workflow. I currently have this workflow set up to do that. This lets you run the server remotely, triggered by certain events, and/or on a schedule, with 50h of free hosting per month with 7GB of RAM. You could even get 14GB of RAM if you can get this working on a Mac or Windows runner. I'm not sure if this ok with the TOS, so I'm not using it.