extract helper for obtaining container ip address

thus keeping the ghastly regexp in one place instead of three.

test/120_ipam_test.sh

@@ -11,7 +11,7 @@ weave_on $HOST2 launch -iprange $UNIVERSE $HOST1
 
 weave_on $HOST1 run -t --name=c1 gliderlabs/alpine /bin/sh
 weave_on $HOST2 run -t --name=c2 gliderlabs/alpine /bin/sh
-C2=$(weave_on $HOST2 ps | grep -o -E '[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}')
+C2=$(container_ip $HOST2 c2)
 assert_raises "exec_on $HOST1 c1 ping -q -c 4 $C2"
 
 end_suite

test/140_ipam_expose_test.sh

@@ -35,7 +35,7 @@ weave_on $HOST1 run -t --name=c1 gliderlabs/alpine /bin/sh
 weave_on $HOST1 run -t --name=c2 gliderlabs/alpine /bin/sh
 weave_on $HOST1 run $C3/24 -t --name=c3 gliderlabs/alpine /bin/sh
 weave_on $HOST1 run $C4/24 -t --name=c4 gliderlabs/alpine /bin/sh
-C1=$(weave_on $HOST1 ps c1 | grep -o -E '[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}')
+C1=$(container_ip $HOST1 c1)
 
 # absence of host connectivity by default
 run_on1 "! $PING $C1"

test/250_dns_ipam_test.sh

@@ -14,7 +14,7 @@ weave_on $HOST2 launch-dns 10.2.254.2/24
 
 weave_on $HOST2 run -t --name=c2 -h seetwo.weave.local gliderlabs/alpine /bin/sh
 weave_on $HOST1 run --with-dns --name=c1 -t aanand/docker-dnsutils /bin/sh
-C2=$(weave_on $HOST2 ps c2 | grep -o -E '[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}')
+C2=$(container_ip $HOST2 c2)
 
 assert "exec_on $HOST1 c1 dig +short seetwo.weave.local" "$C2"
 assert "exec_on $HOST1 c1 dig +short -x $C2" "seetwo.weave.local."

test/config.sh

@@ -88,6 +88,10 @@ exec_on() {
     docker -H tcp://$host:2375 exec $container $@
 }
 
+container_ip() {
+    weave_on $1 ps $2 | grep -o -E '[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}'
+}
+
 # assert_dns_record <host> <container> <name> <ip>
 assert_dns_record() {
     assert "exec_on $1 $2 getent hosts $3 | tr -s ' '" "$4 $3"