Introduction

Hello. I'm a Yin-Yang college student. As a college student, my friends are only online. Therefore, I often play online games. This time is the story.

As a college student, I live in a co-op condominium, so even if I set up a server, I can't open the port and can't play. Therefore, I usually set up a server on AWS EC2.

It would be very convenient to be able to start and stop this server from the voice chat tool Discord.

Then the introduction has become longer, but please.

EC2 preparation

Overview

--__discord-bot EC2 t2.micro instance __ --__game-server EC2 t2.large instance __

The outline of the system looks like this. The point here is

--Two instances are prepared, one for discord response and one for server --Each instance is managed by an in-account security group

Reasons to have two instances

Because I don't have money. At least t2.large performance (8GB of memory) is required to run the minecraft server. But the Discord bot needs to be active all the time, and you can't always launch the more expensive t2.large.

Instance settings

Many people have explained how to start an instance of EC2, so I will omit it.

discord-bot Instance type: t2.micro Inbound rule: No editing OK (SSH 22 port only) Console: AWS commands can be used

The discord BOT uses discord.py. The reason for Python is that I like it. ..

game-server Instance type: t2.large Inbound rule: Added TCP25565 port (for Minecraft)

Implementation

Creating a discord bot account

Please refer to here to create it. Make a note of the access token.

Creating a discord-bot

Work with __discord-bot instance __. Execute the following in the terminal connected by SSH.

python3 -m pip install -U discord.py

Write the main source code. This time, start the server when you type $ start minecraft, and stop the server when you type $ stop minecraft.



import discord
import subprocess
import paramiko
import time

#Replace with your bot's access token
TOKEN = 'your access token'
# game-Please specify the instance id of server
INSTANCEID = 'your instance id'

#Generate the objects needed for the connection
client = discord.Client()

# ***************************
# ***Processing function
# ***************************
class DiscordBOT:
    def __init__(self, client):
        self.SSHClient = None

    async def main(self, discord_event):
        get_text = discord_event.content
        send_text = ""

        if "$start minecraft" in get_text:
            #Launch an instance
            subprocess.call("aws ec2 start-instances --instance-ids {}".format(INSTANCEID), shell=True)
            time.sleep(3)

            #Wait for the instance to start
            subprocess.call("aws ec2 wait instance-running --instance-ids {}".format(INSTANCEID), shell=True)
            time.sleep(3)

            #Get the IP address of the instance
            proc = subprocess.run(["aws ec2 describe-instances --instance-ids {} --query 'Reservations[*].Instances[*].PublicIpAddress' --output text".format(INSTANCEID)], stdout=subprocess.PIPE, stderr=subprocess.PIPE, shell=True)
            ip_add = proc.stdout.decode("utf-8")
            ip_add = ip_add.replace(".", "-").replace("\n", "")
            self.server_ip = ip_add
            time.sleep(3)

            #Create SSH connection client
            self.SSHClient = paramiko.SSHClient()
            self.SSHClient.set_missing_host_key_policy(paramiko.WarningPolicy())
            self.SSHClient.connect('ec2-{}.compute-1.amazonaws.com'.format(ip_add), username='root', password='')
            time.sleep(2)
            
            #Start minecraft server with SSH
            stdin, stdout, stderr = self.SSHClient.exec_command("java -Xmx4096M -Xms4096M -jar server.jar nogui")
            for x in stdout:
                print(x)
            for x in stderr:
                print(x)
            time.sleep(2)

            #Send the IP address for connection to discord
            send_text = "You have successfully launched an instance and connected to a minecraft server.\n After starting the server{}You can connect with".format(ip_add.replace("-", "."))

        elif "$stop minecraft" in get_text:
            #Server outage
            self.SSHClient.connect('ec2-{}.compute-1.amazonaws.com'.format(ip_add), username='root', password='')
            time.sleep(2)
            stdin, stdout, stderr = self.SSHClient.exec_command("stop")
            self.SSHClient.close()

            #Stop instance
            subprocess.call("aws ec2 stop-instances --instance-ids {}".format(INSTANCEID), shell=True)
            send_text = "The server stop is complete."

        if send_text:
            await discord_event.channel.send(send_text)


discordbot = DiscordBOT(client)

@client.event
async def on_ready():
    print('You are now logged')

# on get message
@client.event
async def on_message(message):
    if message.author.bot:
        return

    await discordbot.main(message)

#Launching a bot and connecting to a Discord server
client.run(TOKEN)

Run this on EC2 and you're done.

nohup python3 main.py &

game-server settings

You need to install java. Please refer to here.

In addition, save the minecraft server script (server.jar) in the root user's home directory.

Also, since the SSH connection is made using public key authentication, make the settings there. There is already an article here, so I will introduce it.

How to log in between EC2 instances without an SSH password