Extract HOST_IP default to a function

Change-Id: I263a4351e70b9cfb0965e57e518fe5fd377f4b43
Merge branch 'run-service' into dt-test
Merge branch 'cleanups' into dt-test
Merge branch 'swift-conf' into dt-test
Merge branch 'clean-me' into dt-test
Merge branch 'host-ip' into dt-test