synk ==== Synchronize files between multiple hosts. * one-shot tool (no running daemon) * Compares sha512 to check synchronisation status * Last modification time used to elect a "master" * uses `rsync(1)` for fast copying between peers Installation ------------ Run these commands to build and install `synk` on your system: $ make # make install Usage ----- The following requirements are needed in order for `synk(1)` to work between multiple peers: * `synk` must be installed, and in the `$PATH` on each peer * peers must be able to interconnect via `ssh` (without a prompt) For more information on how this program works, check the synk(1) and synk.conf(5) manpages. As a quick reference, here is an example usage: # Output "peer: HOSTNAME PATH SHA512 MTIME" $ synk -v $HOME/file -h keel.z3bra.org -h orbb.z3bra.org peer: localhost /home/z3bra/file c8e37eb 1473157623 peer: orbb.z3bra.org /home/z3bra/file 6d4af03 1473157643 peer: keel.z3bra.org /home/z3bra/file 005f686 1473157705 master: keel.z3bra.org synk: rsync -azEq --delete keel.z3bra.org:/home/z3bra/file /home/z3bra/file synk: ssh keel.z3bra.org rsync -azEq --delete /home/z3bra/file phobos.z3bra.org:/home/z3bra/file Internal logic -------------- Local client spawns server-mode instances to peers via ssh: synk $FILE \_ ssh phobos.z3bra.org 'synk -s' \_ ssh apophis.z3bra.org 'synk -s' \_ ssh doom.z3bra.org 'synk -s' Client sends metadata for `$FILE` to each peer, which includes the following: * filename (as passed on the command line) * sha512 digest for this file * last modification fime Each peer will then recreate this structure locally, using the given path and send it back to the client, which will build a list of peer/metadata internally. This list is then processed to figure out wether all sha512 digests together match or not. In case a difference is found, the modification times are used to determine a "master", which will `rsync` it local file to all other peers (localhost included). In this case, we have two possibilities: ### localhost is the most recent If localhost is the most recent, we just spawn `rsync(1)` processes locally to update the file with peer that have a different hash: synk file \_ rsync -azEq file phobos.z3bra.org:file \_ rsync -azEq file apophis.z3bra.org:file \_ rsync -azEq file doom.z3bra.org:file ### remote peer X is the most recent We need to spawn `rsync(1)` processes remotely on the host, to sync it with all the peers (except for localhost): synk file \_ rsync -azEq phobos.z3bra.org:file file \_ ssh phobos.z3bra.org 'rsync -azEq file apophis.z3bra.org:file' \_ ssh phobos.z3bra.org 'rsync -azEq file doom.z3bra.org:file' License ------- ISC License. See LICENSE file for copyright and license details.