Unison setup guide

Install Unison

Unison will need to be installed on both servers that are sharing files.

yum install unison

apt-get install unison

Configuration of unison

Before configuring unison itself, you need to ensure that the hosts have shared keys (since this connection is made via SSH).

ssh-keygen -t rsa

ssh-copy-id root@otherserver

Once that's sorted, the unison service itself can be configured.

default unison config file:

/root/.unison/default.prf

root = /
root = ssh://b4sed-01//

path = var/spool/cron/
path = etc/passwd
path = etc/shadow
path = etc/group
path = etc/motd
path = etc/drbd.conf
path = etc/cluster/cluster.conf
path = etc/php.ini
path = etc/nginx/

ignore = Name access.log*

To have unison run automatically, you'll need to configure a cron:

vi /usr/local/bin/sync.sh

Contents of the file (the SISTER= value needs to be updated).

#!/bin/bash
 
SISTER=ABC-WEBDB-01
 
[ -f /var/run/file_sync.pid ] && exit 1;
 
trap "{
        rm /var/run/file_sync.pid;
        exit;
}" EXIT;
 
trap "{
        echo 'Bailing out!' 1>&2
        ssh -T -p2020 root@$SISTER <<<'killall unison; exit' &>/dev/null
}" KILL ABRT INT TERM HUP SEGV
 
touch /var/run/file_sync.pid
/usr/bin/unison -sshargs "-p 2020" -batch -terse -silent -owner -group -numericids -prefer /

Once added, then the cron needs setting up

crontab -e

* * * * * /usr/local/bin/sync.sh > /root/.unison/unison.log

You would then need to add a cron on the 2nd server, you'll need to add this with the '-prefer' omitted, as below:

#!/bin/bash
 
SISTER=ABC-WEBDB-01
 
[ -f /var/run/file_sync.pid ] && exit 1;
 
trap "{
        rm /var/run/file_sync.pid;
        exit;
}" EXIT;
 
trap "{
        echo 'Bailing out!' 1>&2
        ssh -T -p2020 root@$SISTER <<<'killall unison; exit' &>/dev/null
}" KILL ABRT INT TERM HUP SEGV
 
touch /var/run/file_sync.pid
/usr/bin/unison -sshargs "-p 2020" -batch -terse -silent -owner -group -numericids /