Fix loop when a docker host that does not exist was docked.

The problem is it fell back to looking for an alias for the bad hostname,
but to get the aliases, it needs to know which hosts are docked where,
so looped.

debian/changelog

@@ -3,6 +3,7 @@ propellor (0.9.1) UNRELEASED; urgency=medium
   * Docker: Add ability to control when containers restart.
   * Docker: Default to always restarting containers, so they come back 
     up after reboots and docker daemon upgrades.
+  * Fix loop when a docker host that does not exist was docked.
 
  -- Joey Hess <joeyh@debian.org>  Thu, 23 Oct 2014 03:05:22 -0400
 

src/Propellor/Info.hs

@@ -80,7 +80,10 @@ aliasMap = M.fromList . concat .
 	map (\h -> map (\aka -> (aka, h)) $ S.toList $ _aliases $ hostInfo h)
 
 findHost :: [Host] -> HostName -> Maybe Host
-findHost l hn = maybe (findAlias l hn) Just (M.lookup hn (hostMap l))
+findHost l hn = maybe (findAlias l hn) Just (findHostNoAlias l hn)
+
+findHostNoAlias :: [Host] -> HostName -> Maybe Host
+findHostNoAlias l hn = M.lookup hn (hostMap l)
 
 findAlias :: [Host] -> HostName -> Maybe Host
 findAlias l hn = M.lookup hn (aliasMap l)

src/Propellor/Property/Docker.hs

@@ -107,7 +107,7 @@ docked hosts cn = RevertableProperty
 		let cid = ContainerId hn cn
 		ensureProperties [findContainer mhost cid cn $ a cid]
 		
-	mhost = findHost hosts (cn2hn cn)
+	mhost = findHostNoAlias hosts (cn2hn cn)
 
 	setup cid (Container image runparams) =
 		provisionContainer cid