This is a Docker image that provides a choice of Minecraft proxies, such as BungeeCord and Velocity. It is intended to be used in combination with itzg/minecraft-server containers.

Using with itzg/minecraft-server image

When using with the server image itzg/minecraft-server you can disable online mode, which is required by bungeecord, by setting ONLINE_MODE=FALSE, such as

docker run ... -e ONLINE_MODE=FALSE itzg/minecraft-server

The following is an example that can be started with docker compose up -d:

services:
  mc:
    image: itzg/minecraft-server
    environment:
      EULA: "TRUE"
      ONLINE_MODE: "FALSE"
    volumes:
      - mc-data:/data
  proxy:
    image: itzg/mc-proxy
    environment:
      BUNGEE_JAR_REVISION: "1"
      CFG_MOTD: Powered by Docker
      REPLACE_ENV_VARIABLES: "true"
    ports:
      - "25565:25577"
    volumes:
      - ./config.yml:/config/config.yml
      - proxy-data:/server

volumes:
  mc-data:
  proxy-data:

Healthcheck

This image contains mc-monitor and uses its status command to continually check on the container's. That can be observed from the STATUS column of docker ps

CONTAINER ID    IMAGE    COMMAND                         CREATED           STATUS                     PORTS                       NAMES
b418af073764    mc       "/usr/bin/run-bungeecord.sh"    43 seconds ago    Up 41 seconds (healthy)    0.0.0.0:25577->25577/tcp    mc

You can also query the container's health in a script friendly way:

> docker container inspect -f "{{.State.Health.Status}}" mc
healthy

Environment Settings

• TYPE=BUNGEECORD

  The type of the server. When the type is set to CUSTOM, the environment setting BUNGEE_JAR_URL is required.

  Possible values:

  • BUNGEECORD
  • WATERFALL
  • VELOCITY
  • CUSTOM

• MEMORY=512m

  The Java memory heap size to specify to the JVM. Setting this to an empty string will let the JVM calculate the heap size from the container declared memory limit. Be sure to consider adding -XX:MaxRAMPercentage=<n> (with <n> replaced) to JVM_XX_OPTS, where the JVM default is 25%.

• ICON

  Setting this to an image URL will download and (if required) convert the icon to a 64x64 PNG, and place it in /server/server-icon.png.

• OVERRIDE_ICON

  Will override any pre-existing server-icon.png file in the /server directory if ICON is set.

• INIT_MEMORY=${MEMORY}

  Can be set to use a different initial heap size.

• MAX_MEMORY=${MEMORY}

  Can be set to use a different max heap size.

• JVM_OPTS / JVM_XX_OPTS

  Additional space-separated options to pass to the JVM, where JVM_XX_OPTS will be added to the java command-line before JVM_OPTS.

• NETWORKADDRESS_CACHE_TTL=60

  Number of seconds to cache the successful network address lookups. A lower value is helpful when Minecraft server containers are restarted and/or rescheduled and re-assigned a new container IP address.

• PLUGINS

  Used to download a comma seperated list of *.jar urls to the plugins folder.

  -e PLUGINS=https://www.example.com/plugin1.jar,https://www.example.com/plugin2.jar
  

• SPIGET_PLUGINS

  The SPIGET_PLUGINS variable can be set with a comma-separated list of SpigotMC resource IDs to automatically download SpigotMC plugins using the spiget API. Resources that are zip files will be expanded into the plugins directory and resources that are simply jar files will be moved there.

  NOTE: the variable is purposely spelled SPIGET with an "E"

  The resource ID can be located from the numerical part of the URL after the shortname and a dot. For example, the ID is 313 from

  https://www.spigotmc.org/resources/bungeetablistplus.313/
                                                       ===
  

• MODRINTH_PROJECTS

  Comma or newline separated list of project slugs (short name) or IDs. The project ID is located in the "Technical information" section. The slug is the part of the page URL that follows /mod/:

    https://modrinth.com/mod/fabric-api
                             ----------
                              |
                              +-- project slug
  

  Also, a specific version/type can be declared using colon symbol and version id/type after the project slug. The version id can be found in the 'Metadata' section. Valid version types are release, beta, alpha.

  Dependency resolution can be adjusted by setting MODRINTH_DOWNLOAD_DEPENDENCIES to none, optional, or required (the default).

  NOTE The variable MINECRAFT_VERSION must be set to the corresponding Minecraft version.

• ENABLE_RCON

  Enable the rcon server (uses a third-party plugin to work).

  • orblazer/bungee-rcon for BUNGEECORD, WATERFALL, and CUSTOM
  • TribuFuForks/VelocityRcon for VELOCITY

• RCON_PORT

  Define the port for rcon

• RCON_PASSWORD

  Define the password for rcon

Optional Environment Settings

• BUNGEE_JOB_ID=lastStableBuild

  The Jenkins job ID of the artifact to download and run and is used when deriving the default value of BUNGEE_JAR_URL

• BUNGEE_JAR_REVISION

  Defaults to the value of ${BUNGEE_JOB_ID}, but can be set to an arbitrarily incremented value to force an upgrade of the downloaded BungeeCord jar file.

• BUNGEE_BASE_URL

  Default to:

  • (type BUNGEECORD): https://ci.md-5.net/job/BungeeCord
  • (type WATERFALL): https://papermc.io/ci/job/Waterfall/

  Used to derive the default value of BUNGEE_JAR_URL

• BUNGEE_JAR_URL

  If set, can specify a custom, fully qualified URL of the BungeeCord.jar; however, you won't be able reference the other environment variables from within a docker run a compose file. Defaults to:

  • (type: BUNGEECORD): ${BUNGEE_BASE_URL}/${BUNGEE_JOB_ID}/artifact/bootstrap/target/BungeeCord.jar

  This takes precedence over BUNGEE_JAR_FILE.

• BUNGEE_JAR_FILE

  For TYPE=CUSTOM, allows setting a custom BungeeCord JAR that is located inside the container.

  Must be a valid path of an existing file.

• WATERFALL_VERSION=latest

  For TYPE=WATERFALL, allows downloading a specific release stream of Waterfall.

• WATERFALL_BUILD_ID=latest

  For TYPE=WATERFALL, allows downloading a specific build of Waterfall within the given version.

• VELOCITY_VERSION=latest

  For TYPE=VELOCITY, specifies the version of Velocity to download and run.

• VELOCITY_BUILD_ID=latest

  For TYPE=VELOCITY, allows downloading a specific build of Velocity within the given version.

• HEALTH_HOST=localhost

  Allows for configuring the host contacted for container health check.

• HEALTH_USE_PROXY=false

  Set to "true" when using Bungeecord's proxy_protocol option

• ENABLE_JMX=false

  To enable remote JMX, such as for profiling with VisualVM or JMC, add the environment variable ENABLE_JMX=true, set JMX_HOST to the IP/host running the Docker container, and add a port forwarding of TCP port 7091

Volumes

• /server

  The working directory where BungeeCord is started. This is the directory where its config.yml will be loaded.

• /plugins

  Plugins will be copied across from this directory before the server is started.

• /config

  The contents of this directory will be synchronized into the /server directory. Variable placeholders within the files will be processed as described in the section below unless REPLACE_ENV_DURING_SYNC is set to "false".

Ports

• 25577

  The listening port of BungeeCord, which you will typically want to port map to the standard Minecraft server port of 25565 using:

  -p 25565:25577
  

Java Versions

The following table shows the Java versions and CPU architectures supported by the image tags:

Tag	Java	Architectures
latest	17	amd64, arm64, armv7
java8	8	amd64, arm64, armv7
java11	11	amd64, arm64, armv7

Interacting with the server

RCON is enabled by default, so you can exec into the container to access the Bungeecord server console:

docker exec -i mc rcon-cli

Note: The -i is required for interactive use of rcon-cli.

To run a simple, one-shot command, such as stopping a Bungeecord server, pass the command as arguments to rcon-cli, such as:

docker exec mc rcon-cli en

The -i is not needed in this case.

In order to attach and interact with the Bungeecord server, add -it when starting the container, such as

docker run -d -it -p 25565:25577 --name mc itzg/mc-proxy

With that you can attach and interact at any time using

docker attach mc

and then Control-p Control-q to detach.

For remote access, configure your Docker daemon to use a tcp socket (such as -H tcp://0.0.0.0:2375) and attach from another machine:

docker -H $HOST:2375 attach mc

Unless you're on a home/private LAN, you should enable TLS access.

BungeeCord Configuration

BungeeCord Configuration Guide

Generic pack files

To install all the server content (jars, mods, plugins, configs, etc.) from a zip or tgz file, then set GENERIC_PACK to the container path or URL of the archive file.

If multiple generic packs need to be applied together, set GENERIC_PACKS instead, with a comma separated list of archive file paths and/or URLs to files.

To avoid repetition, each entry will be prefixed by the value of GENERIC_PACKS_PREFIX and suffixed by the value of GENERIC_PACKS_SUFFIX, both of which are optional. For example, the following variables

GENERIC_PACKS=configs-v9.0.1,mods-v4.3.6
GENERIC_PACKS_PREFIX=https://cdn.example.org/
GENERIC_PACKS_SUFFIX=.zip

would expand to https://cdn.example.org/configs-v9.0.1.zip,https://cdn.example.org/mods-v4.3.6.zip.

Replacing variables inside configs

Sometimes you have mods or plugins that require configuration information that is only available at runtime. For example if you need to configure a plugin to connect to a database, you don't want to include this information in your Git repository or Docker image. Or maybe you have some runtime information like the server name that needs to be set in your config files after the container starts.

For those cases there is the option to replace defined variables inside your configs with environment variables defined at container runtime.

If you set the environment variable REPLACE_ENV_VARIABLES to TRUE the startup script will go through all files inside your /server volume and replace variables that match your defined environment variables. Variables that you want to replace need to be declared as ${YOUR_VARIABLE}, which is common with shell scripting languages.

With REPLACE_ENV_VARIABLE_PREFIX you can define a prefix, where the default is CFG_, to only match predefined environment variables.

If you want to use a file for a value (such as when using Docker secrets) you can add suffix _FILE to your variable name (in run command). For example, ${CFG_PASSWORD_FILE} would be replaced with the contents of the file specified by the CFG_PASSWORD_FILE environment variable.

Here is a full example where we want to replace values inside a database.yml.

---
database:
  host: ${CFG_DB_HOST}
  name: ${CFG_DB_NAME}
  password: ${CFG_DB_PASSWORD}

This is how your docker-compose.yml file could look like:

version: "3.8"
# Other docker-compose examples in /examples

services:
  proxy:
    image: itzg/mc-proxy
    ports:
      - "25577:25577"
    volumes:
      - "proxy:/server"
    environment:
      # enable env variable replacement
      REPLACE_ENV_VARIABLES: "TRUE"
      # define an optional prefix for your env variables you want to replace
      ENV_VARIABLE_PREFIX: "CFG_"
      # and here are the actual variables
      CFG_DB_HOST: "http://localhost:3306"
      CFG_DB_NAME: "minecraft"
      CFG_DB_PASSWORD_FILE: "/run/secrets/db_password"
    restart: always

volumes:
  proxy:

secrets:
  db_password:
    file: ./db_password

The content of db_password:

ug23u3bg39o-ogADSs

Patching existing files

JSON path based patches can be applied to one or more existing files by setting the variable PATCH_DEFINITIONS to the path of a directory that contains one or more patch definition json files or a patch set json file.

The file and value fields of the patch definitions may contain ${...} variable placeholders. The allowed environment variables in placeholders can be restricted by setting REPLACE_ENV_VARIABLE_PREFIX, which defaults to "CFG_".

The following example shows a patch-set file were various fields in the paper.yaml configuration file can be modified and added:

{
  "patches": [
    {
      "file": "/data/paper.yml",
      "ops": [
        {
          "$set": {
            "path": "$.verbose",
            "value": true
          }
        },
        {
          "$set": {
            "path": "$.settings['velocity-support'].enabled",
            "value": "${CFG_VELOCITY_ENABLED}",
            "value-type": "bool"
          }
        },
        {
          "$put": {
            "path": "$.settings",
            "key": "my-test-setting",
            "value": "testing"
          }
        }
      ]
    }
  ]
}

Supports the file formats:

• JSON
• JSON5
• Yaml
• TOML, but processed output is not pretty

Scenarios

Running non-root

This image may be run as a non-root user but does require an attached /server volume that is writable by that uid, such as:

docker run ... -u $uid -v $(pwd)/data:/server itzg/mc-proxy

Java Versions

The latest image tag is based on Java 21, but alternate image tags are available to run with a different java version.

The image Java variant can be used as shown here:

itzg/mc-proxy:{variant}

or using release version, such as 2024.5.0

itzg/mc-proxy:{release}-{variant}

Variant	Java Version	CPU types
latest	21	amd64,arm64
java21	21	amd64,arm64
java17	17	amd64,arm64,armv7
java11	11	amd64,arm64,armv7
java8	8	amd64,arm64,armv7