Today I made a minecraft mod, using Fabric. Modding sure has changed a lot since I last tried it in Forge, maybe ten years ago! Java's changed a little too, even.

My mod adds a dirt slab, that's it. I didn't really have time to get past the basics, but I think the occasional hack that's just a learning experience is okay.

Code and mod download are both on github this time.

1. Install Redis: https://www.digitalocean.com/community/tutorials/how-to-install-and-use-redis
2. Install Webdis
   
3. Start a minecraft server with computercraft. You will need to have the http API enabled, which is the default.
4. Put down a turtle I recommend a turtle with a crafting square and a pickaxe. I also recommend giving it a label. If you’re not trying the turtle replication challenge, either disable fuel or get a fair bit of starting fuel. Write down the computer’s id.
5. Put down a chunk loader, if you’re in a modpack that has them, or DON’T log out. Computers and turtles can’t operate unless the chunks are loaded. If you’re putting down a chunkloader, I surrounded them with bedrock for foolproofing.

6. Open the turtle and download the following script, changing “redis.example.com” to your own redis instance: pastebin get 8FjggG9w startup
   After you have the script saved as ‘startup’, run it or reboot the computer, and it should start listening for instructions.

   redis = "http://redis.example.com" 
   queue = "sshbot" .. os.getComputerID()
   return_queue = queue .. "_return"
   print("Remote webdis queues on icyego: " .. queue .. " and " .. return_queue)
   print("Receiving remote commands.")
   
   function exec(str)
     print("Running: " .. str)
     f = fs.open("tmp", "w")
     f.write(str)
     f.close()
     p = loadfile("tmp")
    status, err = pcall(function () p = loadfile("tmp"); return p() end)
     if status then
       status, ret = pcall(function() return textutils.serialize(err) end)
       if status then
         result = ret
       else
         result = ""
       end
     else
       result = "Error: " .. err
     end
     print(result)
     return result
   end
   
   print("Now receiving remote commands.")
   while true do
     handle = http.get(redis .. "/BRPOP/" .. queue .. "/5.txt")
     if (handle and handle.getResponseCode() == 200) then 
       str = handle.readAll()
       handle.close()
       str = string.sub(str, string.len(queue) + 1)
       result = exec(str)
       if string.find(result, "Error: ") then
         result2 = exec("return " .. str)
         if string.find(result2, "Error: ") then a=0 else result=result2 end
       end
       http.post(redis, "LPUSH/" .. return_queue .. "/" .. result)
     end
   end
   

7. On your local machine, save the following, again replacing “redis.example.com”:

   #!/bin/bash
   function send() {
     curl -s -X POST -d "LPUSH/sshbot${1}/${2}" "http://redis.example.com" >/dev/null
   
   }
   
   function get() {
     curl -s -X GET "http://redis.example.com/BRPOP/sshbot${1}_return/20.json" | jq .BRPOP[1]
   }
   
   if [ $# -ne 1 ]; then
     echo "Usage: rlwrap ./sshbot <COMPUTER_ID>"
     exit 1
   fi
   ID=$1
   
   while read LINE; do
     send ${ID} "$LINE"
     get ${ID}
   done
   

8. Run: rlwrap ./sshbot , where is the turtle’s ID. You should be able to send commands to the computer now.

• irc.za3k.com
• Port 6667

Or via the webchat, which I recommend.

I’ve also recently updated my home page to look much prettier, in imitation of a Computer Craft cheatsheet I’ve been working on.

I’ve had a lot of trouble getting Minecraft Forge to run headless. They have a friendly installer option that I just can’t use in my situation, but one of the devs seems actively hostile around providing help to headless servers, so I didn’t bother asking forge for help. I thought I’d write up what I had to do to get things working. As a warning, it requires some local work; you can’t do everything headless with these directions.

I’m running Minecraft 1.6.4, with the latest version of forge for that, 9.11.1.965.

1. Locally, download and start the minecraft client for the correct version at least once. Not sure if you’ll need to ‘play online’ or not. If you have the current installer, you need to make a new profile with the correct minecraft version and play that.
2. Copy ~/.minecraft/libraries to the headless machine.
3. Download forge (the installer version, not the universal) from http://files.minecraftforge.net/. The non-adly version is the little star for non-interactive use.

4. Run

   java -jar forge-1.6.4-9.11.1.965-installer.jar --installServer
   

5. Delete the installer, you don’t need it any more.

6. Install any mods you want to the ‘mods’ directory, edit server.properties, etc. Normal server setup.

7. To execute the server, run the file indicated in the installer. In my case, I run

   java -jar minecraftforge-universal-1.6.4-9.11.1.965-v164-pregradle.jar nogui
   

Alternatively, you can install the entire server locally and copy it over.