To mount a Hetzner Storage Box on an Ubuntu server for use with Nextcloud AIO, we'll use SSHFS (SSH Filesystem). This method is secure, relatively easy to set up, and works well with Docker. Here's how to do it:

1. First, install SSHFS on your Ubuntu server:

sudo apt update
sudo apt install sshfs

2. Create a mount point for your Hetzner Storage Box:

sudo mkdir /mnt/hetzner_storage

Then we need to set up SSH key authentication with the Hetzner Storage Box. A script is provided to automate this process:

1. Make the script executable: chmod +x setup_hetzner_storage.sh
2. Run it: ./setup_hetzner_storage.sh

This script will:

1. Generate an SSH key if one doesn't exist.
2. Upload the SSH key to your Hetzner Storage Box.
3. Test the SSH connection.
4. Mount the Storage Box using SSHFS.
5. Verify the mount.

After running this script successfully, your Hetzner Storage Box should be mounted and ready to use with your Nextcloud Docker setup.

Remember to update your Nextcloud Docker Compose file to use the mount point you specified when running the script. For example, if you used /mnt/hetzner_storage as the mount point, your Nextcloud service in the Docker Compose file should include an ENV variable like this:

 environment:
      NEXTCLOUD_DATADIR: /mnt/hetzner_storage/nextcloud 

3. To make this mount persistent across reboots, you'll need to use a systemd service.

[Unit]
Description=Mount Hetzner Storage Box
After=network-online.target
Wants=network-online.target

[Service]
Type=oneshot
RemainAfterExit=yes
ExecStart=/usr/bin/sshfs -o allow_other,IdentityFile=/path/to/your/ssh/key username@your_storage_box.your-storagebox.de:/home /mnt/hetzner_storage
ExecStop=/bin/fusermount -u /mnt/hetzner_storage

[Install]
WantedBy=multi-user.target

Replace /path/to/your/ssh/key with the path to your SSH key, username with your Hetzner Storage Box username, and your_storage_box.your-storagebox.de with your actual Storage Box address.

4. Save this file as /etc/systemd/system/hetzner-storage-mount.service, replacing the ExecStart line with your actual SSHFS command from step 3.

5. Enable and start the service:

sudo systemctl enable hetzner-storage-mount.service
sudo systemctl start hetzner-storage-mount.service