From e6a9a80f274b3364791072d7c77927170ced95c1 Mon Sep 17 00:00:00 2001
From: Joey Hafner <jafner425@gmail.com>
Date: Mon, 9 May 2022 23:33:34 -0700
Subject: [PATCH] Add pregen automation

---
 homelab/server/config/minecraft/README.md | 32 +++++++++++++++++++----
 homelab/server/config/minecraft/bmcp.yml  |  6 +++++
 2 files changed, 33 insertions(+), 5 deletions(-)

diff --git a/homelab/server/config/minecraft/README.md b/homelab/server/config/minecraft/README.md
index dc781200..7aae38cf 100644
--- a/homelab/server/config/minecraft/README.md
+++ b/homelab/server/config/minecraft/README.md
@@ -1,7 +1,10 @@
 ## Connecting to a server's CLI
-`docker exec -it <container_name> rcon-cli --password thanksitzg`
-https://github.com/itzg/docker-minecraft-server#interactive-and-color-console
-https://github.com/itzg/docker-minecraft-server#use-rcon-commands
+To connect to a server's RCON Minecraft console, run
+`docker exec -it minecraft_e6 rcon-cli --password thanksitzg`
+Do not prefix commands with `/`. 
+
+- https://github.com/itzg/docker-minecraft-server#interactive-and-color-console
+- https://github.com/itzg/docker-minecraft-server#use-rcon-commands
 
 ## Updating MC-Router mappings
 MC-Router must be running for all active MC connections. Restarting it kicks everyone off their servers
@@ -19,8 +22,11 @@ Check the following server.properties values:
 | `rcon.port` | `25575` | Set this to what itzg's rcon-cli expects as default |
 | `view-distance` | 10 for lightweight servers, 6 for heavy servers | View distance has great impact on server load |
 
-## Pregenerating Chunks
+## Chunk Pregenerator
+Chunk pregeneration is very valuable for getting a playable SMP server expierence. 
+### Installing Chunk Pregenerator
 Make sure that the [Chunk Pregenerator](https://www.curseforge.com/minecraft/mc-mods/chunkpregenerator) mod is installed. It is compatible with most Minecraft versions between 1.7.2 and 1.16.5.
+### Pregenerating World Spawn
 To pregen chunks, first connect to the server's RCON CLI. Then, run the following, 
 `pregen start gen radius Pregen SQUARE 0 0 100`
 This should take about half an hour and will generate about 40,000 chunks (2r^2). 
@@ -28,4 +34,20 @@ For a job closer to 8 hours, run
 `pregen start gen radius Pregen SQUARE 0 0 500`
 Which will generate about 500,000 chunks.
 
-A Ryzen 7 5800X generates chunks at about 1.35 chunks per tick (27 chunks per second @ 20 TPS).
\ No newline at end of file
+A Ryzen 7 5800X generates chunks at about 1.35 chunks per tick (27 chunks per second @ 20 TPS).
+
+### Automating Chunk Pregen
+Itzg's [container supports](https://github.com/itzg/docker-minecraft-server#use-rcon-commands) `RCON_CMDS_FIRST_CONNECT` and `RCON_CMDS_LAST_DISCONNECT` environment variables, which allow us to automatically begin pregenerating chunks when no one is connected, and pause this task when players begin joining.
+
+Use these variables when the server supports pregen and would benefit from this:
+```
+RCON_CMDS_STARTUP= |-
+    /pregen start gen radius Pregen SQUARE 0 0 500
+RCON_CMDS_FIRST_CONNECT= |-
+    /pregen pause
+RCON_CMDS_LAST_DISCONNECT= |-
+    /pregen continue
+```
+This pregen will significantly reduce load on the server during playtime *unless*:
+* Players explore beyond the pregenerated regions, or
+* Players join the server before a significant area can be pregenerated.
diff --git a/homelab/server/config/minecraft/bmcp.yml b/homelab/server/config/minecraft/bmcp.yml
index ca973e89..bb9267fd 100644
--- a/homelab/server/config/minecraft/bmcp.yml
+++ b/homelab/server/config/minecraft/bmcp.yml
@@ -14,6 +14,12 @@ services:
       - ENABLE_RCON=true # This does not override server.properties
       - RCON_PORT=25575 # This does not override server.properties
       - RCON_PASSWORD=${RCON_PASSWORD} # This does not override server.properties
+      - RCON_CMDS_STARTUP= |-
+        /pregen start gen radius Pregen SQUARE 0 0 500
+      - RCON_CMDS_FIRST_CONNECT= |-
+        /pregen pause
+      - RCON_CMDS_LAST_DISCONNECT= |-
+        /pregen continue
     volumes:
       - $DOCKER_DATA/bmcp:/data:rw
     networks: