Currently, Upstart in Ubuntu does not generate network events. Instead it calls traditional sysvinit. By default NetworkManager is installed and running; rather than emit network events to upstart, it contains a run-parts dispatcher (/etc/NetworkManager/dispatcher.d/) which itself simply relies on ifupdown's run-parts dispatcher (/etc/network/*.d/). In particular you care about /etc/network/if-up.d/ and /etc/network/if-down.d/
First set up a unencrypted ssh keypair, so you can mount the point without a prompt. Write a script, place it in /etc/network/if-up.d/ and make executable. The following was discovered on UbuntuForums and was sufficient for me:
#!/bin/sh
## http://ubuntuforums.org/showthread.php?t=430312
## The script will attempt to mount any fstab entry with an option
## "...,comment=$SELECTED_STRING,..."
## Use this to select specific sshfs mounts rather than all of them.
SELECTED_STRING="sshfs"
# Not for loopback
[ "$IFACE" != "lo" ] || exit 0
## define a number of useful functions
## returns true if input contains nothing but the digits 0-9, false otherwise
## so realy, more like isa_positive_integer
isa_number () {
! echo $1 | egrep -q '[^0-9]'
return $?
}
## returns true if the given uid or username is that of the current user
am_i () {
[ "$1" = "`id -u`" ] || [ "$1" = "`id -un`" ]
}
## takes a username or uid and finds it in /etc/passwd
## echoes the name and returns true on success
## echoes nothing and returns false on failure
user_from_uid () {
if isa_number "$1"
then
# look for the corresponding name in /etc/passwd
local IFS=":"
while read name x uid the_rest
do
if [ "$1" = "$uid" ]
then
echo "$name"
return 0
fi
done </etc/passwd
else
# look for the username in /etc/passwd
if grep -q "^${1}:" /etc/passwd
then
echo "$1"
return 0
fi
fi
# if nothing was found, return false
return 1
}
## Parses a string of comma-separated fstab options and finds out the
## username/uid assigned within them.
## echoes the found username/uid and returns true if found
## echoes "root" and returns false if none found
uid_from_fs_opts () {
local uid=`echo $1 | egrep -o 'uid=[^,]+'`
if [ -z "$uid" ]; then
# no uid was specified, so default is root
echo "root"
return 1
else
# delete the "uid=" at the beginning
uid_length=`expr length $uid - 3`
uid=`expr substr $uid 5 $uid_length`
echo $uid
return 0
fi
}
# unmount all shares first
sh "/etc/network/if-down.d/umountsshfs"
while read fs mp type opts dump pass extra
do
# check validity of line
if [ -z "$pass" -o -n "$extra" -o "`expr substr ${fs}x 1 1`" = "#" ];
then
# line is invalid or a comment, so skip it
continue
# check if the line is a selected line
elif echo $opts | grep -q "comment=$SELECTED_STRING"; then
# get the uid of the mount
mp_uid=`uid_from_fs_opts $opts`
if am_i "$mp_uid"; then
# current user owns the mount, so mount it normally
{ sh -c "mount $mp" &&
echo "$mp mounted as current user (`id -un`)" ||
echo "$mp failed to mount as current user (`id -un`)";
} &
elif am_i root; then
# running as root, so sudo mount as user
if isa_number "$mp_uid"; then
# sudo wants a "#" sign icon front of a numeric uid
mp_uid="#$mp_uid"
fi
{ sudo -u "$mp_uid" sh -c "mount $mp" &&
echo "$mp mounted as $mp_uid" ||
echo "$mp failed to mount as $mp_uid";
} &
else
# otherwise, don't try to mount another user's mount point
echo "Not attempting to mount $mp as other user $mp_uid"
:
echo "Not attempting to mount $mp as other user $mp_uid"
fi
fi
# if not an sshfs line, do nothing
done </etc/fstab
wait
If you have a wifi or otherwise unreliable connection, place the following in /etc/network/if-down.d/:
#!/bin/bash
# Not for loopback!
[ "$IFACE" != "lo" ] || exit 0
# comment this for testing
exec 1>/dev/null # squelch output for non-interactive
# umount all sshfs mounts
mounted=`grep 'fuse.sshfs\|sshfs#' /etc/mtab | awk '{ print $2 }'`
[ -n "$mounted" ] && { for mount in $mounted; do umount -l $mount; done; }
