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Deploying a Minecraft Server with Docker Machine

The previous post explains how to get up and running with Docker machine. This one will be a quick tutorial on setting up a Minecraft server using Machine.

Digital Ocean

Create a new Digital Ocean Machine. We need a 1gb server due to Java’s requirements, so we’ll specify the 1gb DO variant:

> machine-docker create -d digitalocean --digitalocean-access-token=$DO_TOKEN --digitalocean-size=1gb
biscarch-minecraft INFO[0000] Creating SSH key...  INFO[0000] Creating
Digital Ocean droplet...  INFO[0003] Waiting for SSH...  INFO[0155]
"biscarch-minecraft" has been created and is now the active
machine. To point Docker at this machine, run: export
DOCKER_HOST=$(machine url) DOCKER_AUTH=identity

Activate

Run the command suggested to activate the Digital Ocean machine. Remember that we re-named our binaries, so our command will look slightly different:

export DOCKER_HOST=$(machine-docker url) DOCKER_AUTH=identity

Run the Server

After creating the machine, we can run a Minecraft server. Notice that we’ve accepted the EULA using an environment variable.

> machine-docker-1.3.1-dev-identity-auth run -itp 25565:25565 -e EULA=true itzg/minecraft-server
The authenticity of host "$ip:2376" can't be established.
Remote key ID XXXX
Are you sure you want to continue connecting (yes/no)? yes
Unable to find image 'itzg/minecraft-server:latest' locally
Pulling repository itzg/minecraft-server
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Status: Downloaded newer image for itzg/minecraft-server:latest
--2014-12-27 06:06:21--  https://s3.amazonaws.com/Minecraft.Download/versions/versions.json
Resolving s3.amazonaws.com (s3.amazonaws.com)... 54.231.244.4
Connecting to s3.amazonaws.com (s3.amazonaws.com)|54.231.244.4|:443... connected.
HTTP request sent, awaiting response... 200 OK
Length: 20681 (20K) [application/octet-stream]
Saving to: 'STDOUT'

100%[====================================================================================>] 20,681      --.-K/s   in 0.1s

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Downloading minecraft_server.1.8.1.jar ...
[06:06:33] [Server thread/INFO]: Starting minecraft server version 1.8.1
[06:06:33] [Server thread/INFO]: Loading properties
[06:06:33] [Server thread/INFO]: Default game type: SURVIVAL
[06:06:33] [Server thread/INFO]: Generating keypair
[06:06:33] [Server thread/INFO]: Starting Minecraft server on *:25565
[06:06:33] [Server thread/INFO]: Using epoll channel type
[06:06:34] [Server thread/WARN]: Failed to load user banlist:
java.io.FileNotFoundException: banned-players.json (No such file or directory)
    at java.io.FileInputStream.open(Native Method) ~[?:1.7.0_65]
    at java.io.FileInputStream.<init>(FileInputStream.java:146) ~[?:1.7.0_65]
    at com.google.common.io.Files.newReader(Files.java:86) ~[minecraft_server.1.8.1.jar:?]
    at su.g(SourceFile:124) ~[minecraft_server.1.8.1.jar:?]
    at po.z(SourceFile:99) [minecraft_server.1.8.1.jar:?]
    at po.<init>(SourceFile:25) [minecraft_server.1.8.1.jar:?]
    at pp.i(SourceFile:172) [minecraft_server.1.8.1.jar:?]
    at net.minecraft.server.MinecraftServer.run(SourceFile:418) [minecraft_server.1.8.1.jar:?]
    at java.lang.Thread.run(Thread.java:745) [?:1.7.0_65]
[06:06:34] [Server thread/WARN]: Failed to load ip banlist:
java.io.FileNotFoundException: banned-ips.json (No such file or directory)
    at java.io.FileInputStream.open(Native Method) ~[?:1.7.0_65]
    at java.io.FileInputStream.<init>(FileInputStream.java:146) ~[?:1.7.0_65]
    at com.google.common.io.Files.newReader(Files.java:86) ~[minecraft_server.1.8.1.jar:?]
    at su.g(SourceFile:124) ~[minecraft_server.1.8.1.jar:?]
    at po.y(SourceFile:91) [minecraft_server.1.8.1.jar:?]
    at po.<init>(SourceFile:27) [minecraft_server.1.8.1.jar:?]
    at pp.i(SourceFile:172) [minecraft_server.1.8.1.jar:?]
    at net.minecraft.server.MinecraftServer.run(SourceFile:418) [minecraft_server.1.8.1.jar:?]
    at java.lang.Thread.run(Thread.java:745) [?:1.7.0_65]
[06:06:34] [Server thread/WARN]: Failed to load operators list:
java.io.FileNotFoundException: ops.json (No such file or directory)
    at java.io.FileInputStream.open(Native Method) ~[?:1.7.0_65]
    at java.io.FileInputStream.<init>(FileInputStream.java:146) ~[?:1.7.0_65]
    at com.google.common.io.Files.newReader(Files.java:86) ~[minecraft_server.1.8.1.jar:?]
    at su.g(SourceFile:124) ~[minecraft_server.1.8.1.jar:?]
    at po.A(SourceFile:107) [minecraft_server.1.8.1.jar:?]
    at po.<init>(SourceFile:29) [minecraft_server.1.8.1.jar:?]
    at pp.i(SourceFile:172) [minecraft_server.1.8.1.jar:?]
    at net.minecraft.server.MinecraftServer.run(SourceFile:418) [minecraft_server.1.8.1.jar:?]
    at java.lang.Thread.run(Thread.java:745) [?:1.7.0_65]
[06:06:34] [Server thread/WARN]: Failed to load white-list:
java.io.FileNotFoundException: whitelist.json (No such file or directory)
    at java.io.FileInputStream.open(Native Method) ~[?:1.7.0_65]
    at java.io.FileInputStream.<init>(FileInputStream.java:146) ~[?:1.7.0_65]
    at com.google.common.io.Files.newReader(Files.java:86) ~[minecraft_server.1.8.1.jar:?]
    at su.g(SourceFile:124) ~[minecraft_server.1.8.1.jar:?]
    at po.C(SourceFile:123) [minecraft_server.1.8.1.jar:?]
    at po.<init>(SourceFile:30) [minecraft_server.1.8.1.jar:?]
    at pp.i(SourceFile:172) [minecraft_server.1.8.1.jar:?]
    at net.minecraft.server.MinecraftServer.run(SourceFile:418) [minecraft_server.1.8.1.jar:?]
    at java.lang.Thread.run(Thread.java:745) [?:1.7.0_65]
[06:06:34] [Server thread/INFO]: Preparing level "world"
[06:06:34] [Server thread/INFO]: Preparing start region for level 0
[06:06:35] [Server thread/INFO]: Preparing spawn area: 4%
[06:06:36] [Server thread/INFO]: Preparing spawn area: 7%
[06:06:37] [Server thread/INFO]: Preparing spawn area: 9%
[06:06:38] [Server thread/INFO]: Preparing spawn area: 11%
[06:06:39] [Server thread/INFO]: Preparing spawn area: 15%
[06:06:40] [Server thread/INFO]: Preparing spawn area: 17%
[06:06:41] [Server thread/INFO]: Preparing spawn area: 20%
[06:06:42] [Server thread/INFO]: Preparing spawn area: 29%
[06:06:43] [Server thread/INFO]: Preparing spawn area: 40%
[06:06:44] [Server thread/INFO]: Preparing spawn area: 55%
[06:06:46] [Server thread/INFO]: Preparing spawn area: 70%
[06:06:47] [Server thread/INFO]: Preparing spawn area: 82%
[06:06:48] [Server thread/INFO]: Preparing spawn area: 95%
[06:06:48] [Server thread/INFO]: Done (14.248s)! For help, type "help" or "?"

Launch Minecraft

If we ignore the files that we didn’t create for things like the banned players list, that’s all we have to do to run the server! Launch Minecraft and select Multiplayer:

Select “Add Server”

Get the URL

To get the server address, run machine-docker url.

> machine-docker url
tcp://nnn.nnn.nn.nn:2376

After clicking done, we should see our server:

After clicking play the server, we get a nice new world!

What’s next?

Keeping the data around

Spawning servers is cool, but how do we keep the data around after the container is killed?

Let’s take a look inside a running Minecraft container.

> machine-docker-1.3.1-dev-identity-auth ps
CONTAINER ID        IMAGE                          COMMAND              CREATED              STATUS              PORTS                      NAMES
94cf3f854fd8        itzg/minecraft-server:latest   "/start-minecraft"   About a minute ago   Up About a minute   0.0.0.0:25565->25565/tcp   sad_pare
> machine-docker-1.3.1-dev-identity-auth exec -it 94c bash
>> minecraft@94cf3f854fd8:/data$ ls
banned-ips.json  banned-players.json  eula.txt  logs  minecraft_server.1.8.1.jar  ops.json  server.properties  usercache.json  whitelist.json  world

kill the old server (we ran it using -it so Control-C should kill it. If you chose to run it with -d, just use machine-docker-1.3.1-dev-identity-auth ps and machine-docker-1.3.1-dev-identity-auth kill $container_id

After killing the server, we will get kicked from the game:

We can see that there were quite a few files in the /data directory. We’re going to mount a volume there using /opt/craft on the host.

Notice that we’ve also set the Message of the Day (MOTD).

machine-docker-1.3.1-dev-identity-auth run -dp 25565:25565 -e EULA=true -e 'MOTD=Crafty Crafting!' -v /opt/craft:/data itzg/minecraft-server

Let’s ssh in to the Digital Ocean host and see if we have any files:

> machine-docker ssh
root@docker:~# ls /opt/craft/
banned-ips.json  banned-players.json  eula.txt  logs  minecraft_server.1.8.1.jar  ops.json  server.properties  usercache.json  whitelist.json  world

Voila! We have a bunch of files. Now we reconnect to the server (using the Minecraft app) and spend some time doing something (say, chopping down a tree). After that, kill the server as before. The files will stay on the Digital Ocean machine, so we can just restart the server using the same volume mount:

machine-docker-1.3.1-dev-identity-auth run -dp 25565:25565 -e EULA=true -e 'MOTD=Crafty Crafting!' -v /opt/craft:/data itzg/minecraft-server

And look at that, we’ve still cutting down our tree! The server was saved!

A new Seed:

Now we’ll re-run our server with a level seed. It should be added to /opt/craft/server.properties and we can do that through ssh and vi:

> machine-docker ssh biscarch/minecraft
root@docker:~# vi /opt/craft/server.properties

server.properties looks something like this (we’ve just changed the level-seed)

root@docker:~# cat /opt/craft/server.properties
#Minecraft server properties
#Sat Dec 27 10:00:14 UTC 2014
spawn-protection=16
max-tick-time=60000
generator-settings=
force-gamemode=false
allow-nether=true
gamemode=0
enable-query=false
player-idle-timeout=0
difficulty=1
spawn-monsters=true
op-permission-level=4
resource-pack-hash=
announce-player-achievements=true
pvp=true
snooper-enabled=true
level-type=DEFAULT
hardcore=false
enable-command-block=false
max-players=20
network-compression-threshold=256
max-world-size=29999984
server-port=25565
texture-pack=
server-ip=
spawn-npcs=true
allow-flight=false
level-name=world
view-distance=10
resource-pack=
spawn-animals=true
white-list=false
generate-structures=true
online-mode=true
max-build-height=256
level-seed=1785852800490497919
use-native-transport=true
enable-rcon=false
motd=Crafty Crafting!

Now we should be able to blow away /opt/craft/world (if it exists in the container) and our world will get rebuilt:

rm -rf /opt/craft/world

run the server with the volume attached:

machine-docker-1.3.1-dev-identity-auth run -dp 25565:25565 -e EULA=true -e 'MOTD=Crafty Crafting!' -v /opt/craft:/data itzg/minecraft-server

After starting the server with the new seed, just play the server as before (it should still be listed). Turn around and you should see:

Fin

We can use docker machine to ssh into the server and edit /opt/craft/server.properties, which holds a bunch of data we may want to edit. Then just restart the container :)

Happy Crafting!