Re-join cluster when starting

Preserve the cluster server members on stop and use them to join on
start.

Work-around for hashicorp/consul#110

sources/consul/sysvinit.sh

@@ -31,6 +31,7 @@ lockfile="/var/lock/subsys/$prog"
 logfile="/var/log/$prog"
 conffile="/etc/consul.conf"
 confdir="/etc/consul.d"
+membersfile="/var/lib/consul/server_members"
 
 # pull in sysconfig settings
 [ -e /etc/sysconfig/$prog ] && . /etc/sysconfig/$prog
@@ -64,12 +65,42 @@ start() {
 
     [ $RETVAL -eq 0 ] && touch $lockfile
 
+    if [ -e $membersfile ]; then
+        echo -n $"Re-joining cluster: "
+
+        ## allow time to launch
+        sleep 5
+
+        ## I think I want to iterate through every entry in $membersfile and
+        ## return success if any are successfully joined…
+        cat $membersfile | xargs $exec join &>> /dev/null
+
+        RETVAL=$?
+
+        if [ $RETVAL -eq 0 ]; then
+            success
+
+            rm -f $membersfile
+        else
+            failure
+        fi
+
+        echo
+    fi
+
     return $RETVAL
 }
 
 stop() {
     echo -n $"Shutting down $prog: "
 
+    ## store current server members so we can re-join later. exclude ourselves.
+    our_ip=$( ip addr show dev eth0 | awk '/inet / { split($2, cidr, "/"); print cidr[1]; }' )
+    consul members -status=alive -role=consul \
+        | awk '{ split($2, addr, ":"); print addr[1] }' \
+        | fgrep -v $our_ip \
+        > $membersfile
+
     ## graceful shutdown with leave
     $exec leave &> /dev/null