fix(scheduler/coreos): have announcer fail if it cannot get a port

Instead of publishing an invalid upstream for the router to use,
we simply check if the port is nil and exit.

Author: carmstrong

controller/scheduler/coreos.py

@@ -207,14 +207,15 @@ def attach(self, name):
 TimeoutStartSec=20m
 """
 
+# TODO revisit the "not getting a port" issue after we upgrade to Docker 1.1.0
 ANNOUNCE_TEMPLATE = """
 [Unit]
 Description={name} announce
 BindsTo={name}.service
 
 [Service]
 EnvironmentFile=/etc/environment
-ExecStartPre=/bin/sh -c "until docker inspect -f '{{{{range $i, $e := .HostConfig.PortBindings }}}}{{{{$p := index $e 0}}}}{{{{$p.HostPort}}}}{{{{end}}}}' {name} >/dev/null 2>&1; do sleep 2; done; port=$(docker inspect -f '{{{{range $i, $e := .HostConfig.PortBindings }}}}{{{{$p := index $e 0}}}}{{{{$p.HostPort}}}}{{{{end}}}}' {name}); echo Waiting for $port/tcp...; until netstat -lnt | grep :$port >/dev/null; do sleep 1; done"
+ExecStartPre=/bin/sh -c "until docker inspect -f '{{{{range $i, $e := .HostConfig.PortBindings }}}}{{{{$p := index $e 0}}}}{{{{$p.HostPort}}}}{{{{end}}}}' {name} >/dev/null 2>&1; do sleep 2; done; port=$(docker inspect -f '{{{{range $i, $e := .HostConfig.PortBindings }}}}{{{{$p := index $e 0}}}}{{{{$p.HostPort}}}}{{{{end}}}}' {name}); if [[ -z $port ]]; then echo We have no port...; exit 1; fi; echo Waiting for $port/tcp...; until netstat -lnt | grep :$port >/dev/null; do sleep 1; done"
 ExecStart=/bin/sh -c "port=$(docker inspect -f '{{{{range $i, $e := .HostConfig.PortBindings }}}}{{{{$p := index $e 0}}}}{{{{$p.HostPort}}}}{{{{end}}}}' {name}); echo Connected to $COREOS_PRIVATE_IPV4:$port/tcp, publishing to etcd...; while netstat -lnt | grep :$port >/dev/null; do etcdctl set /deis/services/{app}/{name} $COREOS_PRIVATE_IPV4:$port --ttl 60 >/dev/null; sleep 45; done"
 ExecStop=/usr/bin/etcdctl rm --recursive /deis/services/{app}/{name}