docker-mc-backup

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Provides a side-car container to backup itzg/minecraft-server world data.

Environment variables

Common variables:

• SRC_DIR=/data
• BACKUP_NAME=world
• INITIAL_DELAY=2m
• BACKUP_INTERVAL=24h
• PAUSE_IF_NO_PLAYERS=false
• PLAYERS_ONLINE_CHECK_INTERVAL=5m
• PRUNE_BACKUPS_DAYS=7
• PRUNE_RESTIC_RETENTION=--keep-within 7d
• SERVER_PORT=25565
• RCON_HOST=localhost
• RCON_PORT=25575
• RCON_PASSWORD=minecraft
• RCON_PASSWORD_FILE: Can be set to read the RCON password from a file. Overrides RCON_PASSWORD if both are set.
• RCON_RETRIES=5 : Set to a negative value to retry indefinitely
• RCON_RETRY_INTERVAL=10s
• EXCLUDES=*.jar,cache,logs
• BACKUP_METHOD=tar
• RESTIC_ADDITIONAL_TAGS=mc_backups
• TZ : Can be set to the timezone to use for logging
• PRE_BACKUP_SCRIPT, PRE_BACKUP_SCRIPT_FILE, POST_BACKUP_SCRIPT, POST_BACKUP_SCRIPT_FILE: See Pre/post-backup scripts

If PRUNE_BACKUPS_DAYS is set to a positive number, it'll delete old .tgz backup files from DEST_DIR. By default deletes backups older than a week.

If BACKUP_INTERVAL is set to 0 or smaller, script will run once and exit.

Both INITIAL_DELAY and BACKUP_INTERVAL accept times in sleep format: NUMBER[SUFFIX] NUMBER[SUFFIX] .... SUFFIX may be 's' for seconds (the default), 'm' for minutes, 'h' for hours or 'd' for days.

Examples:

• BACKUP_INTERVAL="1.5d" -> backup every one and a half days (36 hours)
• BACKUP_INTERVAL="2h 30m" -> backup every two and a half hours
• INITIAL_DELAY="120" -> wait 2 minutes before starting

The PAUSE_IF_NO_PLAYERS option lets you pause backups if no players are online.

If PAUSE_IF_NO_PLAYERS="true" and there are no players online after a backup is made, then instead of immediately scheduling the next backup, the script will start checking the server's player count every PLAYERS_ONLINE_CHECK_INTERVAL (defaults to 5 minutes). Once a player joins the server, the next backup will be scheduled in BACKUP_INTERVAL.

EXCLUDES is a comma-separated list of glob(3) patterns to exclude from backups. By default excludes all jar files (plugins, server files), logs folder and cache (used by i.e. PaperMC server).

tar backup method

• DEST_DIR=/backups
• LINK_LATEST=false
• TAR_COMPRESS_METHOD=gzip
• ZSTD_PARAMETERS=-3 --long=25 --single-thread

LINK_LATEST is a true/false flag that creates a symbolic link to the latest backup.

TAR_COMPRESS_METHOD is the compression method used by tar. Valid value: gzip bzip2 zstd

ZSTD_PARAMETERS sets the parameters for zstd compression. The --long parameter affects RAM requirements for both compression and decompression (the default of 25 means 2^25 bytes = 32 MB).

restic backup method

See restic documentation on what variables are needed to be defined. At least one of RESTIC_PASSWORD* variables need to be defined, along with RESTIC_REPOSITORY.

Use the RESTIC_ADDITIONAL_TAGS variable to define a space separated list of additional restic tags. The backup will always be tagged with the value of BACKUP_NAME. e.g.: RESTIC_ADDITIONAL_TAGS=mc_backups foo bar will tag your backup with foo, bar, mc_backups and the value of BACKUP_NAME.

You can finetune the retention cycle of the restic backups using the PRUNE_RESTIC_RETENTION variable. Take a look at the restic documentation for details.

EXAMPLE
Setting PRUNE_RESTIC_RETENTION to --keep-daily 7 --keep-weekly 5 --keep-monthly 12 --keep-yearly 75 will keep the most recent 7 daily snapshots, then 4 (remember, 7 dailies already include a week!) last-day-of-the-weeks and 11 or 12 last-day-of-the-months (11 or 12 depends if the 5 weeklies cross a month). And finally 75 last-day-of-the-year snapshots. All other snapshots are removed.

rclone backup method

Rclone acts as the tar backup method but automatically moves the compressed files to a remote drive via rclone.

There are a few special environment variables for the rclone method.

• RCLONE_REMOTE is the name of the remote you've configured in your rclone.conf, see remote setup.
• RCLONE_COMPRESS_METHOD=gzip
• DEST_DIR=/backups is the container path where the archive is temporarily created
• RCLONE_DEST_DIR is the directory on the remote

Other parameters such as PRUNE_BACKUPS_DAYS, ZSTD_PARAMETERS, and BACKUP_NAME are all used as well.

Note that you will need to place your rclone config file in /config/rclone/rclone.conf. This can be done by adding it through docker-compose,

- ./rclone.config:/config/rclone/rclone.conf:ro

or by running the config wizard in a container and mounting the volume.

docker run -it --rm -v rclone-config:/config/rclone rclone/rclone config

then you must bind the volume for the mc-backup process

volumes:
  - rclone-config:/config/rclone

and the service

volumes:
  rclone-config:
    external: true

Volumes

• /data : Should be attached read-only to the same volume as the /data of the itzg/minecraft-server container
• /backups : The volume where incremental tgz files will be created, if using tar backup method.

On-demand backups

If you would like to kick off a backup prior to the next backup interval, you can exec the command backup now within the running backup container. For example, using the Docker Compose example where the service name is backups, the exec command becomes:

docker-compose exec backups backup now

This mechanism can also be used to avoid a long running container completely by running a temporary container, such as:

docker run --rm ...data and backup -v args... itzg/mc-backup backup now

Pre/post-backup script

The PRE_BACKUP_SCRIPT and POST_BACKUP_SCRIPT variables may be set to a bash script to run before and after the backup, respectively. Potential use-cases include sending notifications, or replicating a restic repository to a remote store.

Alternatively PRE_BACKUP_SCRIPT_FILE and POST_BACKUP_SCRIPT_FILE may be set to the path of a script that has been mounted into the container. The file must be executable.

Note that *_FILE variables will be overridden by their non-FILE versions if both are set.

Some notes:

• When specifying the script directly in Docker compose files any $ that are being used to refer to environment variables must be doubled up (i.e. $$) else Compose will try to substitute them

Example

With a executable file called post-backup.sh next to the compose file with the following contents

echo "Backup from $RCON_HOST to $DEST_DIR finished"

and the following compose definition

version: '3.7'

services:
  mc:
    image: itzg/minecraft-server
    ports:
      - "25565:25565"
    environment:
      EULA: "TRUE"
      TYPE: PAPER
    volumes:
      - mc:/data
  backups:
    image: itzg/mc-backup
    environment:
      BACKUP_INTERVAL: "2h"
      RCON_HOST: mc
      PRE_BACKUP_SCRIPT: |
        echo "Before backup!"
        echo "Also before backup from $$RCON_HOST to $$DEST_DIR"
      POST_BACKUP_SCRIPT_FILE: /post-backup.sh
    volumes:
      # mount the same volume used by server, but read-only
      - mc:/data:ro
      # use a host attached directory so that it in turn can be backed up
      # to external/cloud storage
      - ./mc-backups:/backups
      - ./post-backup.sh:/post-backup.sh:ro

volumes:
  mc: {}

Example

Kubernetes

An example StatefulSet deployment is provided in this repository.

The important part is the containers definition of the deployment:

containers:
  - name: mc
    image: itzg/minecraft-server
    env:
      - name: EULA
        value: "TRUE"
    volumeMounts:
      - mountPath: /data
        name: data
  - name: backup
    image: mc-backup
    imagePullPolicy: Never
    securityContext:
      runAsUser: 1000
    env:
      - name: BACKUP_INTERVAL
        value: "2h 30m"
    volumeMounts:
      - mountPath: /data
        name: data
        readOnly: true
      - mountPath: /backups
        name: backups

Docker Compose

version: '3.7'

services:
  mc:
    image: itzg/minecraft-server
    ports:
    - 25565:25565
    environment:
      EULA: "TRUE"
    volumes:
    - mc:/data
  backups:
    image: itzg/mc-backup
    environment:
      BACKUP_INTERVAL: "2h"
      # instead of network_mode below, could declare RCON_HOST
      # RCON_HOST: mc
    volumes:
    # mount the same volume used by server, but read-only
    - mc:/data:ro
    # use a host attached directory so that it in turn can be backed up
    # to external/cloud storage
    - ./mc-backups:/backups
    # share network namespace with server to simplify rcon access
    network_mode: "service:mc"

volumes:
  mc: {}

Restic with rclone

Setup the rclone configuration for the desired remote location

docker run -it --rm -v rclone-config:/config/rclone rclone/rclone config

Setup the itzg/mc-backup container with the following specifics

• Set BACKUP_METHOD to restic
• Set RESTIC_PASSWORD to a restic backup repository password to use
• Use rclone: as the prefix on the RESTIC_REPOSITORY
• Append the rclone config name, colon (:), and specific sub-path for the config type

In the following example CFG_NAME and BUCKET_NAME need to be changed to specifics for the rclone configuration you created:

version: "3"

services:
  mc:
    image: itzg/minecraft-server
    environment:
      EULA: "TRUE"
    ports:
      - 25565:25565
    volumes:
      - mc:/data
  backup:
    image: itzg/mc-backup
    environment:
      RCON_HOST: mc
      BACKUP_METHOD: restic
      RESTIC_PASSWORD: password
      RESTIC_REPOSITORY: rclone:CFG_NAME:BUCKET_NAME
    volumes:
      # mount volume pre-configured using a host mounted file
      - ./rclone.conf:/config/rclone/rclone.conf
      # or configure one into a named volume using
      # docker run -it --rm -v rclone-config:/config/rclone rclone/rclone config
      # and change the above to
      # - rclone-config:/config/rclone
      - mc:/data:ro
      - backups:/backup

volumes:
# Uncomment this if using the config step above
#  rclone-config:
#    external: true
  mc: {}
  backups: {}