[](https://github.com/itzg/docker-minecraft-server/actions)
> If you plan on running a server for a longer amount of time it is highly recommended using a management layer such as [Docker Compose](#using-docker-compose) or [Kubernetes](#deployment-templates-and-examples) to allow for incremental reconfiguration and image upgrades.
By default, the container will download the latest version of the "vanilla" [Minecraft: Java Edition server](https://www.minecraft.net/en-us/download/server) provided by Mojang. The [`VERSION`](#versions) and the [`TYPE`](#server-types) can be configured to create many variations of desired Minecraft server.
**Please ensure you have pulled the latest image** since [all official mitigations](https://www.minecraft.net/en-us/article/important-message--security-vulnerability-java-edition) are automatically applied by the container startup process.
If rcon is disabled you can send commands by passing them as arguments to the packaged `mc-send-to-console` script. For example, a player can be op'ed in the container `mc` with:
```shell
docker exec mc mc-send-to-console op player
| |
+- container name +- Minecraft commands start here
> NOTE: The container path `/data` is pre-declared as a volume, so if you do nothing then it will be allocated as an anonymous volume. As such, it is subject to removal when the container is removed.
In most cases the easier way to persist and work with the minecraft data files is to use the `-v` argument to map a directory on your host machine to the container's `/data` directory, such as the following where `/home/user/minecraft-data` would be a directory of your choosing on your host machine:
docker run -d -v /home/user/minecraft-data:/data ...
When attached in this way you can stop the server, edit the configuration under your attached directory and start the server again to pick up the new configuration.
With Docker Compose, setting up a host attached directory is even easier since relative paths can be configured. For example, with the following `docker-compose.yml` Docker will automatically create/attach the relative directory `minecraft-data` to the container.
> NOTE: if you have SELinux enabled, then you might need to add `:Z` to the end of volume mount specifications, [as described here](https://prefetch.net/blog/2017/09/30/using-docker-volumes-on-selinux-enabled-servers/).
### Converting anonymous `/data` volume to named volume
If you had used the commands in the first section, without the `-v` volume attachment, then an anonymous data volume was created by Docker. You can later bring over that content to a named or host attached volume using the following procedure.
> In this example, it is assumed the original container was given a `--name` of "mc", so change the container identifier accordingly.
When using the image `itzg:/minecraft-server` without a tag, the `latest` image tag is implied from the table below. To use a different version of Java, please use an alternate tag to run your Minecraft server container.
> Keep in mind that some versions of Minecraft server, such as Forge before 1.17, can't work on the newest versions of Java. Instead, one of the Java 8 images should be used. Also, FORGE doesn't support openj9 JVM implementation.
> Some versions of vanilla Minecraft, such as 1.10, also do not run correctly with Java 17. If in doubt, use `java8-multiarch` for any version less than 1.17.
Some orchestration systems, such as Portainer, don't allow for disabling the default `HEALTHCHECK` declared by this image. In those cases you can approximate the disabling of healthchecks by setting the environment variable `DISABLE_HEALTHCHECK` to `true`.
The [examples directory](https://github.com/itzg/docker-minecraft-server/tree/master/examples) also provides examples of deploying the [itzg/minecraft-server](https://hub.docker.com/r/itzg/minecraft-server/) Docker image.
If you're looking for a simple way to deploy this to the Amazon Web Services Cloud, check out the [Minecraft Server Deployment (CloudFormation) repository](https://github.com/vatertime/minecraft-spot-pricing). This repository contains a CloudFormation template that will get you up and running in AWS in a matter of minutes. Optionally it uses Spot Pricing so the server is very cheap, and you can easily turn it off when not in use.
To troubleshoot the container initialization, such as when server files are pre-downloaded, set the environment variable `DEBUG` to `true`. The container logs will include **much more** output, and it is highly recommended including that output when reporting any [issues](https://github.com/itzg/docker-minecraft-server/issues).
To troubleshoot just the command-line used to start the Minecraft server, set the environment variable `DEBUG_EXEC` to `true`.
To troubleshoot any issues with memory allocation reported by the JVM, set the environment variable `DEBUG_MEMORY` to `true`.
The overall version is specified by `VERSION`, [as described in the section above](#versions) and will run the recommended Forge version by default. You can also choose to run a specific Forge version with `FORGEVERSION`, such as `-e FORGEVERSION=14.23.5.2854`.
Enable [Fabric server](https://fabricmc.net/) mode by adding a `-e TYPE=FABRIC` to your command-line. By default, the container will install the latest [fabric-loader](https://fabricmc.net/wiki/documentation:fabric_loader) using the latest [fabric-installer](https://fabricmc.net/use/), against the minecraft server version you have defined with `VERSION` (defaulting to the latest vanilla release of the game).
```
docker run -d -v /path/on/host:/data \
-e TYPE=FABRIC \
-p 25565:25565 -e EULA=TRUE --name mc itzg/minecraft-server
```
See the [Working with mods and plugins](#working-with-mods-and-plugins) section to set up Fabric mods and configuration.
A specific loader version other than the latest can be requested using `FABRIC_LOADER_VERSION`, such as:
```
docker run -d -v /path/on/host:/data ... \
-e FABRIC_LOADER_VERSION=0.12.8
```
If you wish to use an alternative installer you can:
* Specify an alternative version using `FABRIC_INSTALLER_VERSION` (such as `-e FABRIC_INSTALLER_VERSION=0.10.2`)
* Provide the path to a custom installer jar available to the container with `FABRIC_INSTALLER`, relative to `/data` (such as `-e FABRIC_INSTALLER=fabric-installer-0.5.0.32.jar`)
* Provide the URL to a custom installer jar with `FABRIC_INSTALLER_URL` (such as `-e FABRIC_INSTALLER_URL=http://HOST/fabric-installer-0.5.0.32.jar`)
Plugins can either be managed within the `plugins` subdirectory of the [data directory](#data-directory) or you can also [attach a `/plugins` volume](#optional-plugins-mods-and-config-attach-points). If you add plugins while the container is running, you'll need to restart it to pick those up.
> NOTE some of the `VERSION` values are not as intuitive as you would think, so make sure to click into the version entry to find the **exact** version needed for the download. For example, "1.8" is not sufficient since their download naming expects `1.8-R0.1-SNAPSHOT-latest` exactly.
By default, the container will run the latest build of [Paper server](https://papermc.io/downloads) but you can also choose to run a specific build with `-e PAPERBUILD=205`.
If you have attached a host directory to the `/data` volume, then you can install plugins via the `plugins` subdirectory. You can also [attach a `/plugins` volume](#optional-plugins-mods-and-config-attach-points). If you add plugins while the container is running, you'll need to restart it to pick those up.
> NOTE: The `VERSION` variable is used to select an Airplane type to download. The available options are "LATEST" and "PURPUR", both 1.17.1. Airplane does not support 1.18 -- use Paper/Pufferfish/Purpur.
A [Pufferfish](https://github.com/pufferfish-gg/Pufferfish) server, which is "a highly optimized Paper fork designed for large servers requiring both maximum performance, stability, and "enterprise" features."
-e TYPE=PUFFERFISH
> NOTE: The `VERSION` variable is used to select a Pufferfish branch to download from. The available options are "LATEST" and "1.18"
Extra variables:
-`PUFFERFISH_BUILD=lastSuccessfulBuild` : set a specific Pufferfish build to use
-`FORCE_REDOWNLOAD=false` : set to true to force the located server jar to be re-downloaded
A [Purpur](https://purpur.pl3x.net/) server, which is "drop-in replacement for Paper servers designed for configurability, new fun and exciting gameplay features, and performance built on top of Airplane."
[Canyon](https://github.com/canyonmodded/canyon) is a fork of CraftBukkit for Minecraft Beta 1.7.3. It includes multiple enhancements whilst also retaining compatibility with old Bukkit plugins and mods as much as possible.
> **NOTE** only `VERSION=b1.7.3` is supported. Since that version pre-dates the health check mechanism used by this image, that will need to be disabled by setting `DISABLE_HEALTHCHECK=true`.
Beware that current [Sponge](https://www.spongepowered.org) `STABLE` versions for Minecraft 1.12 require using [the Java 8 tag](#running-minecraft-server-on-different-java-version):
A [Limbo](https://github.com/LOOHP/Limbo) server can be run by setting `TYPE` to `LIMBO`.
Configuration options with defaults:
-`LIMBO_BUILD`=LATEST
The `VERSION` will be ignored so locate the appropriate value from [here](https://ci.loohpjames.com/job/Limbo/) to match the version expected by clients.
> NOTE: instead of using format codes in the MOTD, Limbo requires [JSON chat content](https://minecraft.fandom.com/wiki/Raw_JSON_text_format#Java_Edition). If a plain string is provided, which is the default, then it gets converted into the required JSON structure.
[Feed the Beast application](https://www.feed-the-beast.com/) modpacks are supported by using `-e TYPE=FTBA` (**note** the "A" at the end of the type). This server type will automatically take care of downloading and installing the modpack and appropriate version of Forge, so the `VERSION` does not need to be specified.
-`FTB_MODPACK_ID`: **required**, the numerical ID of the modpack to install. The ID can be located by [finding the modpack](https://www.feed-the-beast.com/modpack) and using the "ID" displayed next to the name
-`FTB_MODPACK_VERSION_ID`: optional, the numerical Id of the version to install. If not specified, the latest version will be installed. The "Version ID" can be obtained by drilling into the Versions tab and clicking a specific version.
### Upgrading
If a specific `FTB_MODPACK_VERSION_ID` was not specified, simply restart the container to pick up the newest modpack version. If using a specific version ID, recreate the container with the new version ID.
### Example
The following example runs the latest version of [FTB Presents Direwolf20 1.12](https://ftb.neptunepowered.org/pack/ftb-presents-direwolf20-1-12/):
```
docker run -d --name mc-ftb -e EULA=TRUE \
-e TYPE=FTBA -e FTB_MODPACK_ID=31 \
-p 25565:25565 \
itzg/minecraft-server:multiarch
```
> Normally you will also add `-v` volume for `/data` since the mods and config are installed there along with world data.
## Running a server with a CurseForge modpack
Enable this server mode by adding `-e TYPE=CURSEFORGE` to your command-line,
By default, CurseForge modpacks are expanded into the sub-directory `/data/FeedTheBeast` and executed from there. (The default location was chosen for legacy reasons, when Curse and FTB were maintained together.)
The directory can be changed by setting `CF_BASE_DIR`, such as `-e CF_BASE_DIR=/data`.
Some modpacks have buggy or overly complex start scripts. You can avoid using the bundled start script and use this image's standard server-starting logic by adding `-e USE_MODPACK_START_SCRIPT=false`.
If your server's modpack fails to load with an error [like this](https://support.feed-the-beast.com/t/cant-start-crashlanding-server-unable-to-launch-forgemodloader/6028/2):
unable to launch forgemodloader
then you apply a workaround by adding this to the run invocation:
[packwiz](https://packwiz.infra.link/) is a CLI tool for maintaining and providing modpack definitions, with support for both CurseForge and Modrinth as sources. See the [packwiz tutorial](https://packwiz.infra.link/tutorials/getting-started/) for more information.
To configure server mods using a packwiz modpack, set the `PACKWIZ_URL` environment variable to the location of your `pack.toml` modpack definition:
docker run -d -v /path/on/host:/data -e TYPE=FABRIC \
packwiz modpack defitions are processed before other mod definitions (`MODPACK`, `MODS`, etc.) to allow for additional processing/overrides you may want to perform (in case of mods not available via Modrinth/CurseForge, or you do not maintain the pack).
> packwiz is pre-configured to only download server mods. If client-side mods are downloaded and cause issues, check your pack.toml configuration, and make sure any client-only mods are not set to `"both"`, but rather `"client"` for the side configuration item.
: contents are synchronized into `/data/plugins` for Bukkit related server types. Set `SYNC_SKIP_NEWER_IN_DESTINATION=false` if you want files from `/plugins` to take precedence over newer files in `/data/plugins`.
: contents are synchronized into `/data/config` by default, but can be changed with `COPY_CONFIG_DEST`. For example, `-v ./config:/config -e COPY_CONFIG_DEST=/data` will allow you to copy over files like `bukkit.yml` and so on directly into the server directory. Set `SYNC_SKIP_NEWER_IN_DESTINATION=false` if you want files from `/config` to take precedence over newer files in `/data/config`.
By default, the [environment variable processing](#replacing-variables-inside-configs) is performed on synchronized files that match the expected suffixes in `REPLACE_ENV_SUFFIXES` (by default "yml,yaml,txt,cfg,conf,properties,hjson,json,tml,toml") and are not excluded by `REPLACE_ENV_VARIABLES_EXCLUDES` and `REPLACE_ENV_VARIABLES_EXCLUDE_PATHS`. This processing can be disabled by setting `REPLACE_ENV_DURING_SYNC` to `false`.
If you want old mods/plugins to be removed before the content is brought over from those attach points, then add `-e REMOVE_OLD_MODS=TRUE`. You can fine tune the removal process by specifying the `REMOVE_OLD_MODS_INCLUDE` and `REMOVE_OLD_MODS_EXCLUDE` variables. By default, everything will be removed. You can also specify the `REMOVE_OLD_MODS_DEPTH` (default is 16) variable to only delete files up to a certain level.
For example: `-e REMOVE_OLD_MODS=TRUE -e REMOVE_OLD_MODS_INCLUDE="*.jar" -e REMOVE_OLD_MODS_DEPTH=1` will remove all old jar files that are directly inside the `plugins/` or `mods/` directory.
These paths work well if you want to have a common set of modules in a separate location, but still have multiple worlds with different server requirements in either persistent volumes or a downloadable archive.
> For more flexibility with mods/plugins preparation, you can declare directories to use in [the `MODS` variable](#downloadable-modplugin-pack-for-forge-fabric-and-bukkit-like-servers)
The `SPIGET_RESOURCES` variable can be set with a comma-separated list of SpigotMC resource IDs to automatically download [SpigotMC resources/plugins](https://www.spigotmc.org/resources/) using [the spiget API](https://spiget.org/). Resources that are zip files will be expanded into the plugins directory and resources that are simply jar files will be moved there.
For example, the following will auto-download the [EssentialsX](https://www.spigotmc.org/resources/essentialsx.9089/) and [Vault](https://www.spigotmc.org/resources/vault.34315/) plugins:
This is more complicated because you will be pulling/using the latest mod for the release of your game. To get started make sure you have a [CursedForge API Key](https://docs.curseforge.com/#getting-started). Then use the environmental parameters in your docker build.
Parameters to use the ForgeAPI:
*`MODS_FORGEAPI_KEY` - Required
*`MODS_FORGEAPI_FILE` - Required or use MODS_FORGEAPI_PROJECTIDS (Overrides MODS_FORGEAPI_PROJECTIDS)
*`MODS_FORGEAPI_PROJECTIDS` - Required or use MODS_FORGEAPI_FILE
*`MODS_FORGEAPI_RELEASES` - Default is release, Options: [Release|Beta|Alpha]
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. This can also be used to apply a CurseForge modpack that is missing a server start script and/or Forge installer.
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`.
If applying large generic packs, the update check can be time-consuming since a SHA1 checksum is compared. To skip the update check set `SKIP_GENERIC_PACK_UPDATE_CHECK` to "true". Conversely, the generic pack(s) can be forced to be applied without comparing the checksum by setting `FORCE_GENERIC_PACK_UPDATE` to "true".
As an alternative to `MODS`, the variable `MODS_FILE` can be set with the path to a text file listing a mod/plugin URL on each line. For example, the following
-e MODS_FILE=/extras/mods.txt
would load from a file mounted into the container at `/extras/mods.txt`. That file might look like:
Instead of mounting the `/data` volume, you can instead specify the URL of a ZIP or compressed TAR file containing an archived world. It will be searched for a file `level.dat` and the containing subdirectory moved to the directory named by `$LEVEL`. This means that most of the archived Minecraft worlds downloadable from the Internet will already be in the correct format.
**NOTE:** This URL must be accessible from inside the container. Therefore, you should use an IP address or a globally resolvable FQDN, or else the name of a linked container.
The `WORLD` option can also be used to reference a directory, zip file, or compressed tar file that will be used as a source to clone or extract the world directory.
For example, the following would initially clone the world's content from `/worlds/basic`. Also notice in the example that you should use a read-only volume attachment to ensure the clone source remains pristine.
The world will only be downloaded or copied if it doesn't exist already. Set `FORCE_WORLD_COPY=TRUE` to force overwrite the world on every server start.
Datapacks can be installed in a similar manner to mods/plugins. There are many environment variables which function in the same way they do for [mods](#working-with-mods-and-plugins):
*`DATAPACKS`
*`DATAPACKS_FILE`
*`REMOVE_OLD_DATAPACKS`
*`REMOVE_OLD_DATAPACKS_DEPTH`
*`REMOVE_OLD_DATAPACKS_INCLUDE`
*`REMOVE_OLD_DATAPACKS_EXCLUDE`
Datapacks will be placed in `/data/$LEVEL/datapacks`
By default, the server configuration will be created and set based on the following environment variables, but only the first time the server is started. If the `server.properties` file already exists, the values in them will not be changed.
If you would like to override the server configuration each time the container starts up, you can set the `OVERRIDE_SERVER_PROPERTIES` environment variable like:
This will reset any manual configuration of the `server.properties` file, so if you want to make any persistent configuration changes you will need to make sure you have properly set the proper environment variables in your container configuration.
In the opposite case, you can skip the startup script's creation of `server.properties`, by setting `SKIP_SERVER_PROPERTIES` to "true".
> NOTE: to clear a server property, set the variable to an empty string, such as `-e RESOURCE_PACK=""`. A variables that maps to a server property that is unset, is ignored and the existing `server.property` is left unchanged.
The section symbol (§) and other unicode characters are automatically converted to allow [formatting codes](https://minecraft.fandom.com/wiki/Formatting_codes) to be used consistently with all server versions. For example,
To enforce the whitelist and auto-kick players not included in whitelist configuration, set `ENFORCE_WHITELIST=TRUE`. **By default** any user can join your Minecraft server if it's publicly accessible, regardless of your whitelist configuration.
If whitelist configuration already exists, `WHITELIST_FILE` will not be retrieved and any usernames in `WHITELIST` are **added** to the whitelist configuration. You can enforce regeneration of the whitelist on each server startup by setting `OVERRIDE_WHITELIST` to "true". This will delete the whitelist file before processing whitelist configuration.
> If running Minecraft 1.7.5 or earlier, these variables will apply to `white-list.txt`, with 1.7.6 implementing support for `whitelist.json`. Make sure your `WHITELIST_FILE` is in the appropriate format.
If either `WHITELIST_FILE` or `WHITELIST` is provided, the server property `white-list` is automatically set to `true`, enabline whitelist functionality. Alternatively you can set `ENABLE_WHITELIST=TRUE` to only set the server property `white-list` without modifying the whitelist file. In this case the whitelist can be managed using the `whitelist add` and `whitelist remove` commands. Remember you can set enforcement via the `ENFORCE_WHITELIST` variable.
If ops configuration already exists, `OPS_FILE` will not be retrieved and any usernames in `OPS` are **added** to the ops configuration. You can enforce regeneration of the ops configuration on each server startup by setting `OVERRIDE_OPS` to "true". This will delete the ops file before processing ops configuration.
If set to true, players will be set to spectator mode if they die.
docker run -d -e HARDCORE=false
### Snooper
If set to false, the server will not send data to snoop.minecraft.net server.
docker run -d -e SNOOPER_ENABLED=false
### Max Build Height
The maximum height in which building is allowed.
Terrain may still naturally generate above a low height limit.
docker run -d -e MAX_BUILD_HEIGHT=256
### Max Tick Time
The maximum number of milliseconds a single tick may take before the server watchdog stops the server with the message, A single server tick took 60.00 seconds (should be max 0.05); Considering it to be crashed, server will forcibly shutdown. Once this criteria is met, it calls System.exit(1).
In Minecraft 1.13+ you need to pass json ([generator site](https://misode.github.io/world/)) like this (details see [here](https://github.com/itzg/docker-minecraft-server/issues/999#issuecomment-907849644)):
You can set a link to a custom resource pack and set it's checksum using the `RESOURCE_PACK` and `RESOURCE_PACK_SHA1` options respectively, the default is blank:
By default, server checks connecting players against Minecraft's account database. If you want to create an offline server or your server is not connected to the internet, you can disable the server to try connecting to minecraft.net to authenticate players with environment variable `ONLINE_MODE`, like this
docker run -d -e ONLINE_MODE=FALSE ...
### Allow flight
Allows users to use flight on your server while in Survival mode, if they have a mod that provides flight installed.
The server name (e.g. for bungeecord) can be set like:
docker run -d -e SERVER_NAME=MyServer ...
### Server port
> **WARNING:** only change this value if you know what you're doing. It is only needed when using host networking and it is rare that host networking should be used. Use `-p` port mappings instead.
If you must, the server port can be set like:
docker run -d -e SERVER_PORT=25566 ...
**however**, be sure to change your port mapping accordingly and be prepared for some features to break.
When the environment variable `REPLACE_ENV_IN_PLACE` is set to `true` (the default), the startup script will go through all files inside the container's `/data` path and replace variables that match the container's environment variables. Variables can instead (or in addition to) be replaced in files sync'ed from `/plugins`, `/mods`, and `/config` by setting `REPLACE_ENV_DURING_SYNC` to `true` (defaults to `false`).
Variables that you want to replace need to be declared inside curly brackets and prefixed with a dollar sign, such as `${CFG_YOUR_VARIABLE}`, which is same as many scripting languages.
You can also change `REPLACE_ENV_VARIABLE_PREFIX`, which defaults to "CFG_", to limit which environment variables are allowed to be used. For example, with "CFG_" as the prefix, the variable `${CFG_DB_HOST}` would be subsituted, but not `${DB_HOST}`.
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](https://github.com/itzg/mc-image-helper#patchdefinition) or a [patch set json file](https://github.com/itzg/mc-image-helper#patchset).
Variable placeholders in the patch values 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:
> **NOTES:** Only JSON and Yaml files can be patched at this time. TOML support is planned to be added next. Removal of comments and other cosmetic changes will occur when patched files are processed.
To let the JVM calculate the heap size from the container declared memory limit, unset `MEMORY` with an empty value, such as `-e MEMORY=""`. By default, the JVM will use 25% of the container memory limit as the heap limit; however, as an example the following would tell the JVM to use 75% of the container limit of 2GB of memory:
> The settings above only set the Java **heap** limits. Memory resource requests and limits on the overall container should also account for non-heap memory usage. An extra 25% is [a general best practice](https://dzone.com/articles/best-practices-java-memory-arguments-for-container).
environment variable. The JVM requires `-XX` options to precede `-X` options, so those can be declared in `JVM_XX_OPTS`. Both variables are space-delimited, raw JVM arguments.
For some cases, if e.g. after removing mods, it could be necessary to startup minecraft with an additional `-D` parameter like `-Dfml.queryResult=confirm`. To address this you can use the environment variable `JVM_DD_OPTS`, which builds the params from a given list of values separated by space, but without the `-D` prefix. To make things running under systems (e.g. Plesk), which doesn't allow `=` inside values, a `:` (colon) could be used instead. The upper example would look like this:
To allow time for players to finish what they're doing during a graceful server shutdown, set `STOP_SERVER_ANNOUNCE_DELAY` to a number of seconds to delay after an announcement is posted by the server.
> **NOTE** be sure to adjust Docker's shutdown timeout accordingly, such as using [the -t option on docker-compose down](https://docs.docker.com/compose/reference/down/).
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, such as:
[Aikar has does some research](https://aikar.co/2018/07/02/tuning-the-jvm-g1gc-garbage-collector-flags-for-minecraft/) into finding the optimal JVM flags for GC tuning, which becomes more important as more users are connected concurrently. The set of flags documented there can be added using
When the container is signalled to stop, the Minecraft process wrapper will attempt to send a "stop" command via RCON or console and waits for the process to gracefully finish. By default it waits 60 seconds, but that duration can be configured by setting the environment variable `STOP_DURATION` to the number of seconds.
If you are using a host-attached data directory, then you can have the image setup the Minecraft server files and stop prior to launching the server process by setting `SETUP_ONLY` to `true`.
There are various bug reports on [Mojang](https://bugs.mojang.com) about high CPU usage of servers with newer versions, even with few or no clients connected (e.g. [this one](https://bugs.mojang.com/browse/MC-149018), in fact the functionality is based on [this comment in the thread](https://bugs.mojang.com/browse/MC-149018?focusedCommentId=593606&page=com.atlassian.jira.plugin.system.issuetabpanels%3Acomment-tabpanel#comment-593606)).
An autopause functionality has been added to this image to monitor whether clients are connected to the server. If for a specified time no client is connected, the Java process is stopped. When knocking on the server port (e.g. by the ingame Multiplayer server overview), the process is resumed. The experience for the client does not change.
Of course, even loaded chunks are not ticked when the process is stopped.
**You must greatly increase or disable max-tick-time watchdog functionality.** From the server's point of view, the pausing causes a single tick to take as long as the process is stopped, so the server watchdog might intervene after the process is continued, possibly forcing a container restart. To prevent this, ensure that the `max-tick-time` in the `server.properties` file is set to a very large value or -1 to disable it entirely, which is highly recommended. That can be set with `MAX_TICK_TIME` as described in [the section below](#max-tick-time).
> **NOTE:** Non-vanilla versions might have their own configuration file, you might have to disable their watchdogs separately. For PaperMC servers, you need to send the JVM flag `-Ddisable.watchdog=true`, this can be done with the docker env variable `-e JVM_DD_OPTS=disable.watchdog:true`
On startup the `server.properties` file is checked and, if applicable, a warning is printed to the terminal. When the server is created (no data available in the persistent directory), the properties file is created with the Watchdog disabled.
The utility used to wake the server (`knock(d)`) works at network interface level. So the correct interface has to be set using the `AUTOPAUSE_KNOCK_INTERFACE` variable when using non-default networking environments (e.g. host-networking, Portainer oder NAS solutions). See the description of the variable below.
A starting, example compose file has been provided in [examples/docker-compose-autopause.yml](examples/docker-compose-autopause.yml).
> When configuring kubernetes readiness/liveness health checks with auto-pause enabled, be sure to reference the `mc-health` wrapper script rather than `mc-status` directly.
describes the time between server start and the pausing of the process, when no client connects inbetween (read as timeout initialized)
*`AUTOPAUSE_TIMEOUT_KN`, default `120` (seconds)
describes the time between knocking of the port (e.g. by the main menu ping) and the pausing of the process, when no client connects inbetween (read as timeout knocked)
*`AUTOPAUSE_PERIOD`, default `10` (seconds)
describes period of the daemonized state machine, that handles the pausing of the process (resuming is done independently)
*`AUTOPAUSE_KNOCK_INTERFACE`, default `eth0`
<br>Describes the interface passed to the `knockd` daemon. If the default interface does not work, run the `ifconfig` command inside the container and derive the interface receiving the incoming connection from its output. The passed interface must exist inside the container. Using the loopback interface (`lo`) does likely not yield the desired results.
An option to stop the server after a specified time has been added for niche applications (e.g. billing saving on AWS Fargate). The function is incompatible with the Autopause functionality, as they basically cancel out each other.
Note that the docker container variables have to be set accordingly (restart policy set to "no") and that the container has to be manually restarted.
A starting, example compose file has been provided in [examples/docker-compose-autostop.yml](examples/docker-compose-autostop.yml).
Enable the Autostop functionality by setting:
```
-e ENABLE_AUTOSTOP=TRUE
```
The following environment variables define the behaviour of auto-stopping:
*`AUTOSTOP_TIMEOUT_EST`, default `3600` (seconds)
describes the time between the last client disconnect and the stopping of the server (read as timeout established)
To run this image on a RaspberryPi 3 B+, 4, or newer, use any of the image tags [list in the Java version section](#running-minecraft-server-on-different-java-version) that specify `armv7` for the architecture, which includes `itzg/minecraft-server:latest`.
> If experiencing issues such as "sleep: cannot read realtime clock: Operation not permitted", ensure `libseccomp` is up to date on your host. In some cases adding `:Z` flag to the `/data` mount may be needed, [but use cautiously](https://docs.docker.com/storage/bind-mounts/#configure-the-selinux-label).
