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, 20 insertions, 8 deletions

diff --git a/src/Propellor/Property/Docker.hs b/src/Propellor/Property/Docker.hs
index 64276e87..7b559a50 100644
--- a/src/Propellor/Property/Docker.hs
+++ b/src/Propellor/Property/Docker.hs
@@ -33,10 +33,11 @@ module Propellor.Property.Docker (
 	restartOnFailure,
 	restartNever,
 	-- * Internal use
+	init,
 	chain,
 ) where
 
-import Propellor
+import Propellor hiding (init)
 import Propellor.Types.Info
 import qualified Propellor.Property.File as File
 import qualified Propellor.Property.Apt as Apt
@@ -48,7 +49,8 @@ import Utility.ThreadScheduler
 import Control.Concurrent.Async hiding (link)
 import System.Posix.Directory
 import System.Posix.Process
-import Data.List
+import Prelude hiding (init)
+import Data.List hiding (init)
 import Data.List.Utils
 import qualified Data.Set as S
 
@@ -391,7 +393,7 @@ runningContainer cid@(ContainerId hn cn) image runps = containerDesc cid $ prope
 		liftIO $ writeFile (identFile cid) (show ident)
 		ensureProperty $ boolProperty "run" $ runContainer img
 			(runps ++ ["-i", "-d", "-t"])
-			[shim, "--continue", show (Docker (fromContainerId cid))]
+			[shim, "--continue", show (DockerInit (fromContainerId cid))]
 
 -- | Called when propellor is running inside a docker container.
 -- The string should be the container's ContainerId.
@@ -406,20 +408,20 @@ runningContainer cid@(ContainerId hn cn) image runps = containerDesc cid $ prope
 -- again. So, to make the necessary services get started on boot, this needs
 -- to provision the container then. However, if the container is already
 -- being provisioned by the calling propellor, it would be redundant and
--- problimatic to also provisoon it here.
+-- problimatic to also provisoon it here, when not booting up.
 --
 -- The solution is a flag file. If the flag file exists, then the container
 -- was already provisioned. So, it must be a reboot, and time to provision
 -- again. If the flag file doesn't exist, don't provision here.
-chain :: String -> IO ()
-chain s = case toContainerId s of
+init :: String -> IO ()
+init s = case toContainerId s of
 	Nothing -> error $ "Invalid ContainerId: " ++ s
 	Just cid -> do
 		changeWorkingDirectory localdir
 		writeFile propellorIdent . show =<< readIdentFile cid
 		whenM (checkProvisionedFlag cid) $ do
 			let shim = Shim.file (localdir </> "propellor") (localdir </> shimdir cid)
-			unlessM (boolSystem shim [Param "--continue", Param $ show $ Chain (containerHostName cid)]) $
+			unlessM (boolSystem shim [Param "--continue", Param $ show $ DockerChain (containerHostName cid) (fromContainerId cid)]) $
 				warningMessage "Boot provision failed!"
 		void $ async $ job reapzombies
 		job $ do
@@ -437,7 +439,7 @@ chain s = case toContainerId s of
 provisionContainer :: ContainerId -> Property
 provisionContainer cid = containerDesc cid $ property "provisioned" $ liftIO $ do
 	let shim = Shim.file (localdir </> "propellor") (localdir </> shimdir cid)
-	let params = ["--continue", show $ Chain (containerHostName cid)]
+	let params = ["--continue", show $ DockerChain (containerHostName cid) (fromContainerId cid)]
 	msgh <- mkMessageHandle
 	let p = inContainerProcess cid
 		[ if isConsole msgh then "-it" else "-i" ]
@@ -458,6 +460,13 @@ provisionContainer cid = containerDesc cid $ property "provisioned" $ liftIO $ d
 				hFlush stdout
 				processoutput (Just s) h
 
+chain :: String -> Host -> IO ()
+chain s h = case toContainerId s of
+	Just cid -> onlyProcess (provisioningLock cid) $ do
+		r <- runPropellor h $ ensureProperties $ hostProperties h
+		putStrLn $ "\n" ++ show r
+	Nothing -> error "bad container id"
+
 stopContainer :: ContainerId -> IO Bool
 stopContainer cid = boolSystem dockercmd [Param "stop", Param $ fromContainerId cid ]
 
@@ -549,6 +558,9 @@ setProvisionedFlag cid = do
 checkProvisionedFlag :: ContainerId -> IO Bool
 checkProvisionedFlag = doesFileExist . provisionedFlag
 
+provisioningLock :: ContainerId -> FilePath
+provisioningLock cid = "docker" </> fromContainerId cid ++ ".lock"
+
 shimdir :: ContainerId -> FilePath
 shimdir cid = "docker" </> fromContainerId cid ++ ".shim"