S3 Backup Mod (Fabric • Server-Only)

Back up your Minecraft server world to Amazon S3 on a schedule — with an in-game setup wizard, a manual /backupnow command, and automatic pruning to keep only the newest N backups.

⚠️ Pricing & Liability
By downloading, installing, or using this mod, you accept that the author is not liable for any AWS/S3 charges (storage, requests, data transfer, etc.).
Set your retention! Configure keepLastNS3 to avoid unlimited growth and surprise bills.

Requirements

• Minecraft: Java Edition server 1.21.8
• Fabric Loader and Fabric API (required)
• Java 21
• AWS account with access to an S3 bucket (see IAM Permissions at the bottom)

Features

• Automatic scheduled backups (default every 10 minutes)
• Manual backups via /backupnow
• In-game setup wizard to configure region, bucket, prefix, credentials, and retention
• Retention control: keep only the latest N backups in S3 (default 5)
• Non-blocking: save occurs on the main thread; zipping & upload run on a background thread
• Server-only: no client entrypoint or client mixins

Configuration

A non-secret config file is generated at:

  config/s3-backup-mod.json

  {
    "backupIntervalMinutes": 30,
    "s3Bucket": "YOUR_BUCKET",
    "s3Prefix": "YOUR_PREFIX",
    "awsRegion": "us-east-1",
    "zipBaseName": "world-backup",
    "excludeGlobs": ["logs/**", "crash-reports/**", "backups/**", "*.log", "**/session.lock"],
    "keepLastNS3": 5,
    "keepLatestLocal": false,
    "deleteLocalAfterUpload": true,
    "multipartThresholdMB": 64,
    "multipartPartSizeMB": 256,
    "multipartParallelism": 4
  }

Usage

In-game commands to run with admin permissions:

/s3setup set name YOUR_WORLD_NAME //Optional
/s3setup set interval 30          //Default is 30 minutes
/s3setup set bucket YOUR_BUCKET
/s3setup set prefix YOUR_PREFIX
/s3setup set region us-east-1
/s3setup set multipartThresholdMB 64
/s3setup set multipartPartSizeMB 512
/s3setup set multipartParallelism 4
/s3setup set keep 5

Extra commands:

/backupnow - Backs up the world to S3 when ran
/s3setup show - Shows configuration for mod in-game

IAM Permissions

Ensure your credentials/role can write to the bucket and manage objects for pruning:

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Sid": "ListOnlyWithinPrefix",
      "Effect": "Allow",
      "Action": ["s3:ListBucket"],
      "Resource": "arn:aws:s3:::YOUR_BUCKET",
      "Condition": {
        "StringLike": { "s3:prefix": ["YOUR_PREFIX/*"] }
      }
    },
    {
      "Sid": "WriteReadMPUForBackups",
      "Effect": "Allow",
      "Action": [
        "s3:PutObject",
        "s3:DeleteObject",
        "s3:CreateMultipartUpload",
        "s3:UploadPart",
        "s3:CompleteMultipartUpload",
        "s3:AbortMultipartUpload"
      ],
      "Resource": "arn:aws:s3:::YOUR_BUCKET/YOUR_PREFIX/*"
    }
  ]
}