type safe targets for properties

  * Property types have been improved to indicate what systems they target.
    This prevents using eg, Property FreeBSD on a Debian system.
    Transition guide for this sweeping API change:
    - Change "host name & foo & bar"
      to     "host name $ props & foo & bar"
    - Similarly, `propertyList` and `combineProperties` need `props`
      to be used to combine together properties; they no longer accept
      lists of properties. (If you have such a list, use `toProps`.)
    - And similarly, Chroot, Docker, and Systemd container need `props`
      to be used to combine together the properies used inside them.
    - The `os` property is removed. Instead use `osDebian`, `osBuntish`,
      or `osFreeBSD`. These tell the type checker the target OS of a host.
    - Change "Property NoInfo" to "Property UnixLike"
    - Change "Property HasInfo" to "Property (HasInfo + UnixLike)"
    - Change "RevertableProperty NoInfo" to
      "RevertableProperty UnixLike UnixLike"
    - Change "RevertableProperty HasInfo" to
      "RevertableProperty (HasInfo + UnixLike) UnixLike"
    - GHC needs {-# LANGUAGE TypeOperators #-} to use these fancy types.
      This is enabled by default for all modules in propellor.cabal. But
      if you are using propellor as a library, you may need to enable it
      manually.
    - If you know a property only works on a particular OS, like Debian
      or FreeBSD, use that instead of "UnixLike". For example:
      "Property Debian"
    - It's also possible make a property support a set of OS's, for example:
      "Property (Debian + FreeBSD)"
    - Removed `infoProperty` and `simpleProperty` constructors, instead use
      `property` to construct a Property.
    - Due to the polymorphic type returned by `property`, additional type
      signatures tend to be needed when using it. For example, this will
      fail to type check, because the type checker cannot guess what type
      you intend the intermediate property "go" to have:
        foo :: Property UnixLike
        foo = go `requires` bar
	  where
		go = property "foo" (return NoChange)
      To fix, specify the type of go:
	  	go :: Property UnixLike
    - `ensureProperty` now needs to be passed a witness to the type of the
      property it's used in.
      change this:  foo = property desc $ ... ensureProperty bar
      to this:      foo = property' desc $ \w -> ... ensureProperty w bar
    - General purpose properties like cmdProperty have type "Property UnixLike".
      When using that to run a command only available on Debian, you can
      tighten the type to only the OS that your more specific property works on.
      For example:
        upgraded :: Property Debian
        upgraded = tightenTargets (cmdProperty "apt-get" ["upgrade"])
    - Several utility functions have been renamed:
      getInfo to fromInfo
      propertyInfo to getInfo
      propertyDesc to getDesc
      propertyChildren to getChildren
  * The new `pickOS` property combinator can be used to combine different
    properties, supporting different OS's, into one Property that chooses
    which to use based on the Host's OS.
  * Re-enabled -O0 in propellor.cabal to reign in ghc's memory use handling
    these complex new types.
  * Added dependency on concurrent-output; removed embedded copy.

1 files changed, 12 insertions, 13 deletions

diff --git a/src/Propellor/Property/Cron.hs b/src/Propellor/Property/Cron.hs
index 365e2903..0966a7e5 100644
--- a/src/Propellor/Property/Cron.hs
+++ b/src/Propellor/Property/Cron.hs
@@ -27,9 +27,11 @@ data Times
 -- job file.
 --
 -- The cron job's output will only be emailed if it exits nonzero.
-job :: Desc -> Times -> User -> FilePath -> String -> Property NoInfo
-job desc times (User u) cddir command = combineProperties ("cronned " ++ desc)
-	[ cronjobfile `File.hasContent`
+job :: Desc -> Times -> User -> FilePath -> String -> Property DebianLike
+job desc times (User u) cddir command = combineProperties ("cronned " ++ desc) $ props
+	& Apt.serviceInstalledRunning "cron"
+	& Apt.installed ["util-linux", "moreutils"]
+	& cronjobfile `File.hasContent`
 		[ case times of
 			Times _ -> ""
 			_ -> "#!/bin/sh\nset -e"
@@ -44,22 +46,19 @@ job desc times (User u) cddir command = combineProperties ("cronned " ++ desc)
 				"root" -> "chronic " ++ shellEscape scriptfile
 				_ -> "chronic su " ++ u ++ " -c " ++ shellEscape scriptfile
 		]
-	, case times of
+	& case times of
 		Times _ -> doNothing
 		_ -> cronjobfile `File.mode` combineModes (readModes ++ executeModes)
 	-- Use a separate script because it makes the cron job name
 	-- prettier in emails, and also allows running the job manually.
-	, scriptfile `File.hasContent`
+	& scriptfile `File.hasContent`
 		[ "#!/bin/sh"
 		, "# Generated by propellor"
 		, "set -e"
 		, "flock -n " ++ shellEscape cronjobfile
 			++ " sh -c " ++ shellEscape cmdline
 		]
-	, scriptfile `File.mode` combineModes (readModes ++ executeModes)
-	]
-	`requires` Apt.serviceInstalledRunning "cron"
-	`requires` Apt.installed ["util-linux", "moreutils"]
+	& scriptfile `File.mode` combineModes (readModes ++ executeModes)
   where
 	cmdline = "cd " ++ cddir ++ " && ( " ++ command ++ " )"
 	cronjobfile = "/etc" </> cronjobdir </> name
@@ -75,13 +74,13 @@ job desc times (User u) cddir command = combineProperties ("cronned " ++ desc)
 		| otherwise = '_'
 
 -- | Installs a cron job, and runs it niced and ioniced.
-niceJob :: Desc -> Times -> User -> FilePath -> String -> Property NoInfo
+niceJob :: Desc -> Times -> User -> FilePath -> String -> Property DebianLike
 niceJob desc times user cddir command = job desc times user cddir
 	("nice ionice -c 3 sh -c " ++ shellEscape command)
 
 -- | Installs a cron job to run propellor.
-runPropellor :: Times -> Property NoInfo
-runPropellor times = withOS "propellor cron job" $ \o -> 
-	ensureProperty $
+runPropellor :: Times -> Property UnixLike
+runPropellor times = withOS "propellor cron job" $ \w o -> 
+	ensureProperty w $
 		niceJob "propellor" times (User "root") localdir
 			(bootstrapPropellorCommand o ++ "; ./propellor")