propellor spin

Propellor/Property.hs

@@ -33,6 +33,16 @@ combineProperties desc ps = Property desc $ go ps NoChange
 			FailedChange -> return FailedChange
 			_ -> go ls (r <> rs)
 
+-- | Combines together two properties, resulting in one property
+-- that ensures the first, and if the first succeeds, ensures the second.
+-- The property uses the description of the first property.
+before :: Property -> Property -> Property
+p1 `before` p2 = Property (propertyDesc p1) $ do
+	r <- ensureProperty p1
+	case r of
+		FailedChange -> return FailedChange
+		_ -> ensureProperty p2
+
 -- | Makes a perhaps non-idempotent Property be idempotent by using a flag
 -- file to indicate whether it has run before.
 -- Use with caution.

Propellor/Property/Apt.hs

@@ -147,9 +147,12 @@ autoRemove = runApt ["-y", "autoremove"]
 
 -- | Enables unattended upgrades. Revert to disable.
 unattendedUpgrades :: RevertableProperty
-unattendedUpgrades = RevertableProperty (go True) (go False)
+unattendedUpgrades = RevertableProperty enable disable
   where
-	go enabled = (if enabled then installed else removed) ["unattended-upgrades"]
+	enable = setup True `before` installed ["cron"]
+	disable = setup False
+
+	setup enabled = (if enabled then installed else removed) ["unattended-upgrades"]
 		`onChange` reConfigure "unattended-upgrades"
 			[("unattended-upgrades/enable_auto_updates" , "boolean", v)]
 		`describe` ("unattended upgrades " ++ v)

config-joey.hs

@@ -61,7 +61,7 @@ host _ = Nothing
 -- | This is where Docker containers are set up. A container
 -- can vary by hostname where it's used, or be the same everywhere.
 container :: HostName -> Docker.ContainerName -> Maybe (Docker.Container)
-container parenthost name
+container _parenthost name
 	-- Simple web server, publishing the outside host's /var/www
 	| name == "webserver" = Just $ Docker.containerFrom
 		(image $ System (Debian Unstable) "amd64")

debian/changelog

@@ -1,6 +1,8 @@
 propellor (0.2.4) UNRELEASED; urgency=medium
 
   * ipv6to4: Ensure interface is brought up automatically on boot.
+  * Enabling unattended upgrades now ensures that cron is installed and
+    running to perform them.
 
  -- Joey Hess <joeyh@debian.org>  Tue, 08 Apr 2014 18:07:12 -0400