From: Andrew Ruthven <andrew@etc.gen.nz>
Date: Thu, 26 Apr 2012 08:55:02 +0000 (+1200)
Subject: Add commwnts.
X-Git-Tag: v0.2~3
X-Git-Url: http://git.etc.gen.nz/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=1d336dc66e49b83f1aa20770cf237c75523168bd;p=etc-obnam.git

Add commwnts.
---

diff --git a/run-backup b/run-backup
index 43cd3ce..0eb54f3 100755
--- a/run-backup
+++ b/run-backup
@@ -1,11 +1,20 @@
 #!/bin/bash
 
+# Conditionally run obnam.
+#
+# If $HOST_NAME is defined, check that we can ping it.
+# If $HOST_MAC is defined, check that the arp/neighbour table has a matching
+#   MAC address.
+# If those conditions are meet, then backup $SOURCE, but first grab some
+# debconf data so we can reconstruct the packages installed if we need to.
+
 . /etc/default/etc-obnam
 
 CLIENT=$(hostname)
 SOURCE=${SOURCE:-/home /etc}
 WORKDIR=/var/lib/etc-obnam
 
+# Check that the host is local, support both IPv4 and IPv6.
 function check_host() {
   local type=$1
   if [ "x$type" != "xA" -a "x$type" != "xAAAA" ]
@@ -20,23 +29,29 @@ function check_host() {
     return 0
   fi
 
+  # Make sure that we can get DNS details for the host first.
   local ip=$(host -t $type $HOST_NAME | grep address | awk '{ print $NF }' | head -1)
   if [ "x$ip" = "x" ]
   then
     return 1
   fi
 
+  # ping or ping6?
   local cmd=ping
   if [ $type = "AAAA" ]
   then
     cmd=ping6
   fi
 
+  # ping at will.
   if ! $cmd -n -c3 $HOST_NAME &> /dev/null
   then
     return 1
   fi
 
+  # Check the neighbour table.  If $HOST_NAME is *us* then we won't have an
+  # entry, that is why HOST_MAC is optional. Could check ip link to see if
+  $ $HOST_MAC is on this box.
   local mac=$(ip neigh | egrep "^$ip " | grep REACHABLE | awk '{ print $5 }' )
   if [ $(echo $mac | wc -l ) -ne 1 ]
   then
@@ -51,6 +66,8 @@ function check_host() {
   return 0
 }
 
+# Grab enough details to hopefully be able to reconstuct the installed
+# packages.
 function capture_debconf_info() {
   # Keep a list of the installed files
   dpkg --get-selections > $WORKDIR/installed.packages.new
@@ -69,7 +86,7 @@ function capture_debconf_info() {
   fi
 }
 
-
+# Check to see if the right host is present, if it is, do a backup.
 if ( check_host 'AAAA' -o check_host 'A'  )
 then
   capture_debconf_info