feat: mysql-bkup v2 on bkupkit

MysQL backup and restore built on the shared bkupkit core:
streaming end to end, with no dump held in memory or written to
local disk.

docs/how-tos/backup-to-ssh.md

@@ -23,15 +23,16 @@ This section explains how to set up and configure SSH-based backups.
 3. **Required Environment Variables**  
    The following environment variables are mandatory for SSH-based backups:
 
-    - `SSH_HOST`: The hostname or IP address of the remote server.
-    - `SSH_USER`: The username for SSH authentication.
+    - `SFTP_HOST`: The hostname or IP address of the remote server.
+    - `SFTP_USER`: The username for SSH authentication.
     - `REMOTE_PATH`: The directory on the remote server where backups will be stored.
-    - `SSH_IDENTIFY_FILE`: The path to the private key file for SSH authentication.
-    - `SSH_PORT`: The SSH port (default is `22`).
-    - `SSH_PASSWORD`: (Optional) Use this only if you are not using a private key for authentication.
+    - `SFTP_IDENTITY_FILE`: The path to the private key file for SSH authentication (`SFTP_IDENTITY_FILE` still works).
+    - `SFTP_KNOWN_HOSTS`: A `known_hosts` file used to verify the server's host key. Host keys are verified by default since v2; `SFTP_INSECURE_IGNORE_HOST_KEY=true` turns the check off (not recommended).
+    - `SFTP_PORT`: The SSH port (default is `22`).
+    - `SFTP_PASSWORD`: (Optional) Use this only if you are not using a private key for authentication.
 
    {: .note }
-   **Security Recommendation**: Using a private key (`SSH_IDENTIFY_FILE`) is strongly recommended over password-based authentication (`SSH_PASSWORD`) for better security.
+   **Security Recommendation**: Using a private key (`SFTP_IDENTITY_FILE`) is strongly recommended over password-based authentication (`SFTP_PASSWORD`) for better security.
 
 ---
 
@@ -54,16 +55,17 @@ services:
          - DB_PORT=3306
          - DB_HOST=mysql
          - DB_NAME=database
-         - DB_USERNAME=username
+         - DB_USER=username
          - DB_PASSWORD=password
          ## SSH Configuration
-         - SSH_HOST="hostname"
-         - SSH_PORT=22
-         - SSH_USER=user
+         - SFTP_HOST=hostname
+         - SFTP_PORT=22
+         - SFTP_USER=user
          - REMOTE_PATH=/home/jkaninda/backups
-         - SSH_IDENTIFY_FILE=/tmp/id_ed25519
+         - SFTP_IDENTITY_FILE=/tmp/id_ed25519
+         - SFTP_KNOWN_HOSTS=/config/known_hosts
          ## Optional: Use password instead of private key (not recommended)
-         #- SSH_PASSWORD=password
+         #- SFTP_PASSWORD=password
 
       # Ensure the mysql-bkup container is connected to the same network as your database
       networks:
@@ -97,18 +99,19 @@ services:
       - DB_PORT=3306
       - DB_HOST=postgres
       - DB_NAME=database
-      - DB_USERNAME=username
+      - DB_USER=username
       - DB_PASSWORD=password
       ## SSH Configuration
-      - SSH_HOST="hostname"
-      - SSH_PORT=22
-      - SSH_USER=user
+      - SFTP_HOST=hostname
+      - SFTP_PORT=22
+      - SFTP_USER=user
       - REMOTE_PATH=/home/jkaninda/backups
-      - SSH_IDENTIFY_FILE=/tmp/id_ed25519
+      - SFTP_IDENTITY_FILE=/tmp/id_ed25519
+      - SFTP_KNOWN_HOSTS=/config/known_hosts
       ## Optional: Delete old backups after a specified number of days
       #- BACKUP_RETENTION_DAYS=7
       ## Optional: Use password instead of private key (not recommended)
-      #- SSH_PASSWORD=password
+      #- SFTP_PASSWORD=password
 
     # Ensure the mysql-bkup container is connected to the same network as your database
     networks:
@@ -124,6 +127,6 @@ networks:
 
 - **Cron Expression**: Use the `--cron-expression` flag or `BACKUP_CRON_EXPRESSION` environment variable to define the backup schedule. For example, `0 1 * * *` runs the backup daily at 1:00 AM.
 - **Backup Retention**: Optionally, use the `BACKUP_RETENTION_DAYS` environment variable to automatically delete backups older than a specified number of days.
-- **Security**: Always prefer private key authentication (`SSH_IDENTIFY_FILE`) over password-based authentication (`SSH_PASSWORD`) for enhanced security.
+- **Security**: Always prefer private key authentication (`SFTP_IDENTITY_FILE`) over password-based authentication (`SFTP_PASSWORD`) for enhanced security.
 
 ---