Installing a Web, Email & MySQL Database Cluster on Debian 8.4 Jessie with ISPConfig 3.1 - Page 4

7 Install Unison

Next we install Unison. Unison is used to sync the /var/www directory between server1 and server2.

Install unison on server1 and server2 with

apt-get install unison

Now we install a unison configuration file on server1:

Create a new file /root/.unison/web:

mkdir /root/.unison
vi /root/.unison/web.prf

... and add the following content:

# Roots of the synchronization
root = /var/www
root = ssh://192.168.0.106//var/www
 
# Paths to synchronize
#path = www
#path = vmail
 
# Some regexps specifying names and paths to ignore
#ignore = Path stats    ## ignores /var/www/stats
#ignore = Path stats/*  ## ignores /var/www/stats/*
#ignore = Path */stats  ## ignores /var/www/somedir/stats, but not /var/www/a/b/c/stats
#ignore = Name *stats   ## ignores all files/directories that end with "stats"
#ignore = Name stats*   ## ignores all files/directories that begin with "stats"
#ignore = Name *.tmp    ## ignores all files with the extension .tmp
ignore = Name sess_*
ignore = Name *access.log*
ignore = Name error.log
ignore = Name webalizer.conf
   
#          When set to true, this flag causes the user interface to skip
#          asking for confirmations on non-conflicting changes. (More
#          precisely, when the user interface is done setting the
#          propagation direction for one entry and is about to move to the
#          next, it will skip over all non-conflicting entries and go
#          directly to the next conflict.)
auto=true
   
#          When this is set to true, the user interface will ask no
#          questions at all. Non-conflicting changes will be propagated;
#          conflicts will be skipped.
batch=true
   
#          !When this is set to true, Unison will request an extra
#          confirmation if it appears that the entire replica has been
#          deleted, before propagating the change. If the batch flag is
#          also set, synchronization will be aborted. When the path
#          preference is used, the same confirmation will be requested for
#          top-level paths. (At the moment, this flag only affects the
#          text user interface.) See also the mountpoint preference.
confirmbigdel=true
   
#          When this preference is set to true, Unison will use the
#          modification time and length of a file as a `pseudo inode
#          number' when scanning replicas for updates, instead of reading
#          the full contents of every file. Under Windows, this may cause
#          Unison to miss propagating an update if the modification time
#          and length of the file are both unchanged by the update.
#          However, Unison will never overwrite such an update with a
#          change from the other replica, since it always does a safe
#          check for updates just before propagating a change. Thus, it is
#          reasonable to use this switch under Windows most of the time
#          and occasionally run Unison once with fastcheck set to false,
#          if you are worried that Unison may have overlooked an update.
#          The default value of the preference is auto, which causes
#          Unison to use fast checking on Unix replicas (where it is safe)
#          and slow checking on Windows replicas. For backward
#          compatibility, yes, no, and default can be used in place of
#          true, false, and auto. See the section "Fast Checking" for more
#          information.
fastcheck=true

#          When this flag is set to true, the group attributes of the
#          files are synchronized. Whether the group names or the group
#          identifiers are synchronizeddepends on the preference numerids.
group=true
   
#          When this flag is set to true, the owner attributes of the
#          files are synchronized. Whether the owner names or the owner
#          identifiers are synchronizeddepends on the preference
#          extttnumerids.
owner=true
   
#          Including the preference -prefer root causes Unison always to
#          resolve conflicts in favor of root, rather than asking for
#          guidance from the user. (The syntax of root is the same as for
#          the root preference, plus the special values newer and older.)
#          This preference is overridden by the preferpartial preference.
#          This preference should be used only if you are sure you know
#          what you are doing!
prefer=newer
   
#          When this preference is set to true, the textual user interface
#          will print nothing at all, except in the case of errors.
#          Setting silent to true automatically sets the batch preference
#          to true.
silent=true
   
#          When this flag is set to true, file modification times (but not
#          directory modtimes) are propagated.
times=false

#          When this flag is set, Unison will log all changes to the filesystems on a file.
log=false

#          When this flag is set to true, groups and users are synchronized numerically, rather than by name.
#          The special uid 0 and the special group 0 are never mapped via user/group names even if this
#          preference is not set.
numericids=true

We want to automate synchronization, so we create a small script and create a cronjob on server1:

mkdir /root/scripts
vi /root/scripts/unison.sh

and add the following content:

#!/bin/sh
lockdir=/tmp
UNISON=/usr/bin/unison
LOGGER=/usr/bin/logger

if [ ! -f /$lockdir/unison ]; then
        touch $lockdir/unison

        $UNISON -testserver web
        rc=$?
        if [[ $rc != 0 ]] ; then
                echo "error"
                $LOGGER -d -t unison "web - error connecting remote"
        else
                $UNISON web
        fi

        rm $lockdir/unison
else
        $LOGGER -d -t unison "unison already running"
fi

make the script executable:

chmod 700 /root/scripts/unison.sh

And run the first sync. To get some output during the sync set silent = false in /root/.unsion/web.prf. Afterwards, start unison:

/root/scripts/unison.sh

Finally, we create the cronjob:

crontab -e

# unison
*  * * * *  /root/scripts/unison.sh > /dev/null