A $5/month cloud Minecraft server

Introduction

Problems? Improvements? File a bug report. I can't offer a rapid response, but I do intend for this to actually work!

If your child is a full-bore Minecrafter, he or she is probably going to want to join a server at some point, to play with other people. Finding a public server that is also safe is no easy task. One alternative is to create your own "invite-only" server, so that you and/or your child can control who can play along.

Minecraft has its own service, Minecraft Realms, that is quite easy to use. But it costs $13/month to run a server, or $10.40/month if you let them bill your credit card automatically. If you don't mind investing a bit more effort, and you are reasonably comfortable typing commands on a Unix command line, you can get your own server up and running for only $5/month. This server will probably handle 6-8 users, but can be expanded as needed (for more money, of course).

Prerequisites

These instructions make the following assumptions. If these assumptions are not satisfied, then you might consider Minecraft Realms.

• You have at least one paid Minecraft account to serve as the "operator" of your server. When this player connects to the server using a Minecraft client, he/she will have access to operator commands that can, for instance, add or remove players from the whitelist, switch between creative and survival mode, and so forth.
• You are roughly familiar with a Unix command line. You don't have to understand what every typed command below actually means.
• You need to know how to use a Unix text editor like vi or nano. Honestly, nano is pretty straightforward.
• You need an SSH client on your host computer. On the Mac, this means firing up the Terminal application and typing ssh <hostname>. There are SSH apps available for the PC, iPad, and (probably) Android as well.

References

• https://minecraft.net/download
• http://otoris.com/host-your-own-minecraft-and-mumble-server-for-5month/
• https://www.digitalocean.com/community/tutorials/how-to-add-swap-on-centos-7
• http://minecraft.gamepedia.com/Tutorials/Server_startup_script
• https://www.digitalocean.com/community/tutorials/how-to-set-up-a-minecraft-server-on-linux
• http://minecraft.gamepedia.com/Commands
• https://minecraft.net (of course!)

Here we go!

1. Create a DigitalOcean account. DigitalOcean is a well regarded cloud server provider that I use for business as well as for Minecraft. Use my referral code to get $10 credit right off the bat, which means you are not spending money to try this out. If you stick with it long enough to rack up $25 in bills, I will get $25 in credit myself. And of course, you can start referring your friends, too, once you sign up.

2. Log into DigitalOcean, click "Create", and configure your server:

   • Droplet hostname: your choice; e.g. "Minecraft".
   • Select size: $5MB/mo (512MB, 1CPU, 20GB SSD)
   • Select region: stick with the default unless you happen to live closer to one of the other regions.
   • Available settings: no changes needed.
   • Select image: from the "Linux distributions" tab, choose CentOS 7.0 x64. Feel free to choose another distribution that you are more familiar with, but these instructions were built using CentOS.
   • Add SSH Keys: if you have an key, provide it. If not, or you don't know what that means, no problem---DigitalOcean will email a root password.

   Once the server is created, it will give you the IP address (e.g., 173.172.171.170); and, if necessary, it will email your root password.

3. Log into the machine as root. For instance, on the Mac, open Terminal and type this command (changing the address, of course):

   ssh root@173.172.171.170
   

   Once you are connected to the server, you need to change the root password, install Java and Screen, and add a swap file. Without a swap file, the Minecraft server will die whenever it runs out of memory. (And it will.)

   passwd
   	<change your root password>
   yum install java-sdk screen
   fallocate -l 4G /swapfile		
   chmod 600 /swapfile
   mkswap /swapfile
   swapon /swapfile
   

   Edit the file /etc/fstab and add this line:

   /swapfile swap swap sw 0 0
   

   A note about Java. At first, I went through some additional hoops to download and install the absolute latest greatest verison of Java from Oracle. This worked great for vanilla Minecraft, but some of the mods I installed are incompatible with Java 8. The instructions above install Java 7 instead. Since you're not using this server for anything else (right?) I don't think you need worry too much about using an older Java.

4. It's not good form to run any sort of server with root-level access. So create a user account that will hold the minecraft program, log in as that, and do some initial preparations.

   useradd minecraft
   passwd minecraft
   	<change minecraft's password>
   su minecraft
   cd ~
   mkdir backups
   

   You'll see what the backups directory is for later.

5. Download the latest minecraft server software, and rename it.

   wget https://s3.amazonaws.com/Minecraft.Download/versions/1.8.1/minecraft_server.1.8.1.jar
   mv minecraft_server.1.8.1.jar minecraft_server.jar
   

6. Create a new file called ops.txt with the Unix text editor. In this file, place the Minecrat usernames of anyone you wish to give "operator" access to this server. You need at least one operator, but one is enough for now. Any operator can add more operators, if desired, right from the Minecraft client itself during gameplay.

7. Time to run the server! Here's the magic command:

   java -Xmx480M -Xms480M -XX:+UseConcMarkSweepGC \
   	-XX:+CMSIncrementalPacing -XX:ParallelGCThreads=1 \
   	-XX:+AggressiveOpts -jar minecraft_server.jar nogui
   

   The first time you run this, it will create some files---and then stop! It needs you to accept the EULA before it will go further. Edit the file eula.txt that it just created, and change the last line to "eula=TRUE". Then re-run the server.

   java -Xmx480M -Xms480M -XX:+UseConcMarkSweepGC \
   	-XX:+CMSIncrementalPacing -XX:ParallelGCThreads=1 \
   	-XX:+AggressiveOpts -jar minecraft_server.jar nogui
   

   Assuming everything is working properly, you'll see the logs show that it is building the world. Once the logs settle down and say it's done building, move on to the next step.

8. Now you need to try connecting to the server!

   • Fire up your local Minecraft client.
   • Click "Multiplayer"
   • Click "Add Server". Enter a name for the server, and the IP address of the server (e.g., 173.172.171.170).
   • Click "Done."
   • Now select the server you just added, and click "Join Server."

   If everything is working right, you'll be transported to a brand new Minecraft world! Once you have confirmed everything is working, disconnect your Minecraft client from the server, and then halt the server itself by typing Ctrl-C.

9. With the server shut down, edit the file server.properties and consider changing a few of the parameters therein:

   • white-list=false: you should change this to white-list=true to prevent univited persons from joining. Any operator will be able to add people to the whitelist with the /whitelist command.
   • gamemode=1: change this to "gamemode=0" for creative.
   • level-type=DEFAULT: this is a standard terrain-filled world. If you really like creative, you may want to change this to level-type=FLAT to get a flat world with no terrain.
   • max-players=20: this is more than your little 512MB server can handle. You can reduce this to, say, max-players=5 if you want, but if your whitelist is short it won't matter.
   • motd=A Minecraft Server: this is just a Message of The Day. Change it to something fun!

   Here is a reference guide for this file.

   If you changed the level-type to FLAT, you will need to delete the world that Minecraft has already created so that it will create a new one. To do so, remove the entire world directory:

   rm -rf world
   

   In any case, don't restart the server yet!

10. Drop back down to root (ctrl-D, log in again, whatever) and download this init script, which will start Minecraft automatically on boot:

    cd ~
    wget https://github.com/mcg1969/mcserver/raw/master/initscript.sh
    

    This is an edited version of the init script offered on this page. Specifically, we have edited the MCPATH, BACKUPPATH, MINHEAP, and MAXHEAP values to suit our specific server and directory choices above. So if you deviated from the instructions above, you may need to edit this file to suit.

    Now move the script into its proper position, fire it up, and see if it works!

    cp initscript.sh /etc/init.d/minecraft
    chmod +x /etc/init.d/minecraft
    chkconfig --add minecraft
    service minecraft start
    

    Don't be alarmed if it takes almost 10 seconds before it says "minecraft_server.jar is now running."

11. Try connecting to the server again with your Minecraft client! Hopefully all should be well.

12. If that works, there's one more thing you may want to do. The startup script has a backup facility that makes periodic backups of your world. which might come in handy if someone really screws up. Type

    crontab -e
    

    and add the following line to have hourly backups saved:

    15 * * * * /etc/init.d/minecraft backup
    

    TODO: set up a logrotate script so that you don't fill your entire disk with these backups.

13. At this point, you should be able to log out of the server and work with the Minecraft client as an operator. Some useful, and hopefully self-explanatory, commands:

    /op <username>
    /whitelist <username>
    /banlist <username>
    

    More commands and explanations can be found on this page.

14. If you ever need to log into the server to see what's going on, log in as the minecraft user, not root, unless you know you need to. Then type

    screen -r
    

    to switch over to the running minecraft server (assuming it's still running). There you can type commands to help you manage the server. To exit this screen without shutting down the server, type <CTRL>-A <CTRL>-D.