mysql-bkup/docs/how-tos/encrypt-backup.md

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Encrypt backups using GPG	default	How Tos	8

Encrypt Backup

The image supports encrypting backups using one of two methods: GPG with a passphrase or GPG with a public key. When a GPG_PASSPHRASE or GPG_PUBLIC_KEY environment variable is set, the backup archive will be encrypted and saved as a .sql.gpg or .sql.gz.gpg file.

{: .warning } To restore an encrypted backup, you must provide the same GPG passphrase or private key used during the backup process.

---

Key Features

• Cipher Algorithm: aes256
• Automatic Restoration: Backups encrypted with a GPG passphrase can be restored automatically without manual decryption.
• Manual Decryption: Backups encrypted with a GPG public key require manual decryption before restoration.

---

Using GPG Passphrase

To encrypt backups using a GPG passphrase, set the GPG_PASSPHRASE environment variable. The backup will be encrypted and can be restored automatically.

Example Configuration

services:
  mysql-bkup:
    # In production, lock your image tag to a specific release version
    # instead of using `latest`. Check https://github.com/jkaninda/mysql-bkup/releases
    # for available releases.
    image: jkaninda/mysql-bkup
    container_name: mysql-bkup
    command: backup -d database
    volumes:
      - ./backup:/backup
    environment:
      - DB_PORT=3306
      - DB_HOST=mysql
      - DB_NAME=database
      - DB_USER=username
      - DB_PASSWORD=password
      ## Required to encrypt backup
      - GPG_PASSPHRASE=my-secure-passphrase
    # Ensure the pg-bkup container is connected to the same network as your database
    networks:
      - web

networks:
  web:

---

Using GPG Public Key

To encrypt backups using a GPG public key, set the GPG_PUBLIC_KEY environment variable to the path of your public key file. To restore such backups, set GPG_PRIVATE_KEY (a file path or the inline armored key; /config/gnupg/private_key.asc is picked up automatically) and, if the key is protected, GPG_PRIVATE_KEY_PASSPHRASE (defaults to GPG_PASSPHRASE).

Example Configuration

services:
  mysql-bkup:
    # In production, lock your image tag to a specific release version
    # instead of using `latest`. Check https://github.com/jkaninda/mysql-bkup/releases
    # for available releases.
    image: jkaninda/mysql-bkup
    container_name: mysql-bkup
    command: backup -d database
    volumes:
      - ./backup:/backup
      - ./public_key.asc:/config/public_key.asc
    environment:
      - DB_PORT=3306
      - DB_HOST=mysql
      - DB_NAME=database
      - DB_USER=username
      - DB_PASSWORD=password
      ## Required to encrypt backup
      - GPG_PUBLIC_KEY=/config/public_key.asc
    # Ensure the pg-bkup container is connected to the same network as your database
    networks:
      - web

networks:
  web:

---

Manual Decryption

If you encrypted your backup using a GPG public key, you must manually decrypt it before restoration. Use the gnupg tool for decryption.

Decrypt Using a Passphrase

gpg --batch --passphrase "my-passphrase" \
  --output database_20240730_044201.sql.gz \
  --decrypt database_20240730_044201.sql.gz.gpg

Decrypt Using a Private Key

gpg --output database_20240730_044201.sql.gz \
  --decrypt database_20240730_044201.sql.gz.gpg

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Key Notes

• Automatic Restoration: Backups encrypted with a GPG passphrase can be restored directly without manual decryption.
• Private key restore: Backups encrypted with a GPG public key restore directly when GPG_PRIVATE_KEY is set; manual decryption also works.
• Fail closed: if GPG_PUBLIC_KEY (or any configured key) cannot be read, the backup fails instead of being stored unencrypted.
• Security: Always keep your GPG passphrase and private key secure. Use Kubernetes Secrets or other secure methods to manage sensitive data.

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Using age

age is a modern alternative to GPG. Set AGE_RECIPIENTS (one or more age1... or ssh-ed25519 ... public keys, comma or newline separated, or AGE_RECIPIENTS_FILE) and backups are saved as .sql.gz.age. Restore with the matching identity in AGE_IDENTITY (AGE-SECRET-KEY-...) or AGE_IDENTITY_FILE (default /config/age/identity.txt).

    environment:
      - AGE_RECIPIENTS=age1ql3z7hjy54pw3hyww5ayyfg7zqgvc7w3j2elw8zmrj2kg5sfn9aqmcac8p
      # restore:
      # - AGE_IDENTITY_FILE=/run/secrets/age_identity

AGE_PASSPHRASE encrypts with a passphrase instead (it needs about 256 MiB of memory for the key derivation). ENCRYPTION=auto|none|gpg|age chooses explicitly; with auto (default) GPG wins when both GPG and age keys are set. Decrypt by hand with age -d -i key.txt file.sql.gz.age | gunzip.