Add option to use existing Fabric install to avoid metadata query

[itzg]

Discussion in Discord

Hi, I have a question about the Minecraft server Docker image.

I have this compose:

services:
  mc:
    image: itzg/minecraft-server:java21-jdk
    tty: true
    stdin_open: true
    restart: always
    ports:
      - "25565:25565"
    environment:
      EULA: "TRUE"
      TYPE: "FABRIC"
      ENABLE_COMMAND_BLOCK: "true"
      ENABLE_WHITELIST: "true"
      WHITELIST: |-
        xx
        xxx
      VERSION: "1.21.1"
      MEMORY: "10240M"
      MAX_PLAYERS: "2"
      OPS: |-
        xx
      ALLOW_FLIGHT: "true"
    volumes:
      - "./data:/data"

The server always tries to download Fabric when TYPE=FABRIC. In Spain, sometimes Cloudflare is blocked due to football events (yeah, it sucks). When this happens, meta.fabricmc.net and its IPs are blocked, among other sites.

Is it possible to avoid downloading Fabric every time the server starts?