Syncer

Features:

• One-way syncing of one or more folders via rsync
• Limits the maximum amount of space used on the destination
• Keeps files on the destination for selected amount of time before rotating it out and replacing it with newer files
• The use-case is i.e. syncing photos from the NAS/server to the Android phone with Termux (with sshd and rsync) which uploads files to some cloud service (i.e. Google Photos).
• Tested on PHP 8.2 (php-sqlite3 and pecl inotify extensions required)

Example usage:

1. G Pixel phone with G photos sync enabled
   1. Termux from F-Droid
   2. Termux:API from F-Droid
   3. (optional but recommended) Termux:Boot from F-Droid - to start sshd automatically
   4. setup sshd, install rsync, setup Termux API (pkg install termux-api), setup storage mount termux-setup-storage
2. Server/NAS with Nextcloud connected through VPN (i.e. Wireguard) to the network, where you keep your G Pixel phone (i.e. home network)
3. Nextcloud client on your phone with photo sync enabled
4. Syncer (this app) running on the server/NAS with proper configuration
   1. don't forget to add your server's/NAS public ssh key to the ~/.ssh/authorized_keys on your G Pixel Termux
   2. set /etc/syncer/config.ini on your server/NAS with proper values
   3. your post_sync_command should probably contain ssh -p 8022 user@<your G Pixel's VPN IP> termux-media-scan -r /mnt/sdcard/DCIM
   4. your directory[name] should contain path where your Nextcloud keeps photos synced from your phone
   5. set dest_size_max to the amount of free storage on your G Pixel device (in bytes) 15000000000 is recommended value for 32GB variant
   6. set keep_time_min it's the minimum time (in seconds) to keep photos on the G Pixel device to allow them to be synced completely to G photos. Change this according to your needs. If your upload speed is slow, you probably want to increase this value.
   7. set temp_dir path so it is at the same mountpoint as (photos) source directory

         |                                                                      |
+--------+                                                             +--------+
| source |                                                             | G Pixel|
| phone  |                                                             |(Termux)|
+--------+                       +--------------------+                +--------+  
| 1 2 3  | ---Nextcloud sync-->  | Server/NAS         |   ---syncer--> | 1 2 3  |
| 4 5 6  |                       | running Nextcloud  |                | 4 5 6  |  
| 7 8 9  |                       +--------------------+                | 7 8 9  | 
| * 0 #  |                                                             | * 0 #  |
+--------+                                                             +--------+
                                                                          |
                                                                          |
                                                                          v
                                                                     .-~~~-.
                                                             .- ~ ~-(       )_ _
                                                            /                     ~ -.
                                                           |      G Photos             \
                                                            \                         .'
                                                              ~- . _____________ . -~

TODO:

• maybe create single phar archive?
• exception handling
• implement Google Photos API - it can't be used as it does not provide way to filter or sort by uploaded date or total count of objects.