prevent multiple concurrent provisioning inside docker container

Lock a lock file while provisioning inside, otherwise propellor could be
running to init the container when the system has just booted, or the
container was just started from being stopped, and at the same time,
propellor run outside the container chains into it to provision.

Previously, simplesh prevented this in a different way.

1 files changed, 6 insertions, 20 deletions

diff --git a/src/Propellor/CmdLine.hs b/src/Propellor/CmdLine.hs
index e41ab39d..d9a95de2 100644
--- a/src/Propellor/CmdLine.hs
+++ b/src/Propellor/CmdLine.hs
@@ -7,8 +7,6 @@ import System.Environment (getArgs)
 import Data.List
 import System.Exit
 import System.PosixCompat
-import Control.Exception (bracket)
-import System.Posix.IO
 
 import Propellor
 import Propellor.Protocol
@@ -86,10 +84,8 @@ defaultMain hostlist = do
 	go _ (Edit field context) = editPrivData field context
 	go _ ListFields = listPrivDataFields hostlist
 	go _ (AddKey keyid) = addKey keyid
-	go _ (Chain hn) = withhost hn $ \h -> do
-		r <- runPropellor h $ ensureProperties $ hostProperties h
-		putStrLn $ "\n" ++ show r
-	go _ (Docker hn) = Docker.chain hn
+	go _ (DockerChain hn s) = withhost hn $ Docker.chain s
+	go _ (DockerInit hn) = Docker.init hn
 	go _ (GitPush fin fout) = gitPushHelper fin fout
 	go True cmdline@(Spin _) = buildFirst cmdline $ go False cmdline
 	go True cmdline = updateFirst cmdline $ go False cmdline
@@ -97,27 +93,17 @@ defaultMain hostlist = do
 	go False cmdline@(SimpleRun hn) = buildFirst cmdline $
 		go False (Run hn)
 	go False (Run hn) = ifM ((==) 0 <$> getRealUserID)
-		( onlyProcess $ withhost hn mainProperties
+		( onlyprocess $ withhost hn mainProperties
 		, go True (Spin hn)
 		)
 	go False (Update _) = do
 		forceConsole
-		onlyProcess update
+		onlyprocess update
 
 	withhost :: HostName -> (Host -> IO ()) -> IO ()
 	withhost hn a = maybe (unknownhost hn hostlist) a (findHost hostlist hn)
-
-onlyProcess :: IO a -> IO a
-onlyProcess a = bracket lock unlock (const a)
-  where
-	lock = do
-		l <- createFile lockfile stdFileMode
-		setLock l (WriteLock, AbsoluteSeek, 0, 0)
-			`catchIO` const alreadyrunning
-		return l
-	unlock = closeFd
-	alreadyrunning = error "Propellor is already running on this host!"
-	lockfile = localdir </> ".lock"
+	
+	onlyprocess = onlyProcess (localdir </> ".lock")
 
 unknownhost :: HostName -> [Host] -> IO a
 unknownhost h hosts = errorMessage $ unlines