diff --git a/b9.cabal b/b9.cabal
--- a/b9.cabal
+++ b/b9.cabal
@@ -1,5 +1,5 @@
 name:                b9
-version:             0.5.43
+version:             0.5.44
 
 synopsis:            A tool and library for building virtual machine images.
 
@@ -75,7 +75,6 @@
                    , B9.B9Config.LibVirtLXC
                    , B9.B9Config.Repository
                    , B9.B9Monad
-                   , B9.Builder
                    , B9.Content.AST
                    , B9.Content.ErlangPropList
                    , B9.Content.ErlTerms
@@ -86,7 +85,6 @@
                    , B9.DiskImages
                    , B9.DSL
                    , B9.ExecEnv
-                   , B9.Invokation
                    , B9.LibVirtLXC
                    , B9.MBR
                    , B9.PartitionTable
diff --git a/src/cli/Main.hs b/src/cli/Main.hs
--- a/src/cli/Main.hs
+++ b/src/cli/Main.hs
@@ -7,27 +7,34 @@
 
 main :: IO ()
 main = do
-    b9Opts <- parseCommandLine
-    result <- invokeB9 (applyB9RunParameters b9Opts)
-    exit (maybe False (const True) result)
-    where exit success = when (not success) (exitWith (ExitFailure 128))
+    b9Opts  <- parseCommandLine
+    applyB9RunParameters b9Opts
 
+
 -- | A data structure that contains the `B9Invokation`
 -- as well as build parameters.
-data B9RunParameters a =
+data B9RunParameters =
   B9RunParameters
             B9ConfigOverride
-            (B9Invokation a ())
+            Cmd
             BuildVariables
 
-applyB9RunParameters :: B9RunParameters a -> B9Invokation a ()
-applyB9RunParameters (B9RunParameters overrides action vars) = do
-    modifyInvokationConfig
-      (over envVars (++ vars) . const (overrides ^. customB9Config))
-    mapM_ overrideB9ConfigPath (overrides ^. customB9ConfigPath)
-    action
+type Cmd = B9ConfigAction IO ()
 
-parseCommandLine :: IO (B9RunParameters ())
+applyB9RunParameters :: B9RunParameters -> IO ()
+applyB9RunParameters (B9RunParameters overrides act vars) =
+    let cfg =
+            noB9ConfigOverride
+                &  customB9Config
+                %~ ( over envVars (++ vars)
+                   . const (overrides ^. customB9Config)
+                   )
+                &  maybe id
+                         overrideB9ConfigPath
+                         (overrides ^. customB9ConfigPath)
+    in  execB9ConfigAction act cfg
+
+parseCommandLine :: IO B9RunParameters
 parseCommandLine = execParser
     ( info
         (helper <*> (B9RunParameters <$> globals <*> cmds <*> buildVars))
@@ -38,8 +45,8 @@
         )
     )
   where
-    b9HelpHeader =
-        linebreak <> text ("B9 - a benign VM-Image build tool v. " ++ b9VersionString)
+    b9HelpHeader = linebreak
+        <> text ("B9 - a benign VM-Image build tool v. " ++ b9VersionString)
 
 
 globals :: Parser B9ConfigOverride
@@ -125,37 +132,50 @@
         = let minLogLevel = if verbose
                   then Just LogTrace
                   else if quiet then Just LogError else Nothing
-              b9cfg  = mempty & verbosity       .~ minLogLevel
-                              & logFile         .~ logF
-                              & profileFile     .~ profF
-                              & buildDirRoot    .~ buildRoot
-                              & keepTempDirs    .~ keep
-                              & uniqueBuildDirs .~ not notUnique
-                              & repository      .~ repo
-                              & repositoryCache .~ (Path <$> mRepoCache)
-
+              b9cfg =
+                  mempty
+                      &  verbosity
+                      .~ minLogLevel
+                      &  logFile
+                      .~ logF
+                      &  profileFile
+                      .~ profF
+                      &  buildDirRoot
+                      .~ buildRoot
+                      &  keepTempDirs
+                      .~ keep
+                      &  uniqueBuildDirs
+                      .~ not notUnique
+                      &  repository
+                      .~ repo
+                      &  repositoryCache
+                      .~ (Path <$> mRepoCache)
           in  B9ConfigOverride
                   { _customB9ConfigPath = Path <$> cfg
-                  , _customB9Config = b9cfg
+                  , _customB9Config     = b9cfg
                   }
 
-cmds :: Parser (B9Invokation () ())
+cmds :: Parser Cmd
 cmds = subparser
     (  command
           "version"
-          ( info (pure (ignoreActionResults runShowVersion))
+          ( info (pure runShowVersion)
                  (progDesc "Show program version and exit.")
           )
     <> command
            "build"
            ( info
-               (ignoreActionResults . runBuildArtifacts <$> buildFileParser)
+               (void . runBuildArtifacts <$> buildFileParser)
+
                (progDesc "Merge all build file and generate all artifacts.")
            )
     <> command
            "run"
            ( info
-               (ignoreActionResults <$> (runRun <$> sharedImageNameParser <*> many (strArgument idm)))
+               (   (\x y -> void (runRun x y))
+               <$> sharedImageNameParser
+               <*> many (strArgument idm)
+               )
                ( progDesc
                    "Run a command on the lastest version of the specified shared image. All modifications are lost on exit."
                )
@@ -163,7 +183,7 @@
     <> command
            "push"
            ( info
-               (ignoreActionResults . runPush <$> sharedImageNameParser)
+               (runPush <$> sharedImageNameParser)
                ( progDesc
                    "Push the lastest shared image from cache to the selected  remote repository."
                )
@@ -171,7 +191,7 @@
     <> command
            "pull"
            ( info
-               (ignoreActionResults . runPull <$> optional sharedImageNameParser)
+               (runPull <$> optional sharedImageNameParser)
                ( progDesc
                    "Either pull shared image meta data from all repositories, or only from just a selected one. If additionally the name of a shared images was specified, pull the newest version from either the selected repo, or from the repo with the most recent version."
                )
@@ -179,7 +199,7 @@
     <> command
            "clean-local"
            ( info
-               (pure (ignoreActionResults runGcLocalRepoCache))
+               (pure runGcLocalRepoCache)
                ( progDesc
                    "Remove old versions of shared images from the local cache."
                )
@@ -187,23 +207,24 @@
     <> command
            "clean-remote"
            ( info
-               (pure (ignoreActionResults runGcRemoteRepoCache))
+               (pure runGcRemoteRepoCache)
                ( progDesc
                    "Remove cached meta-data of a remote repository. If no '-r' is given, clean the meta data of ALL remote repositories."
                )
            )
     <> command
            "list"
-           (info (pure (ignoreActionResults runListSharedImages)) (progDesc "List shared images."))
+           (info (pure (void runListSharedImages)) (progDesc "List shared images."))
     <> command
            "add-repo"
-           ( info (ignoreActionResults . runAddRepo <$> remoteRepoParser)
+           ( info (runAddRepo <$> remoteRepoParser)
                   (progDesc "Add a remote repo.")
            )
     <> command
            "reformat"
-           ( info (ignoreActionResults . runFormatBuildFiles <$> buildFileParser)
-                  (progDesc "Re-Format all build files.")
+           ( info
+               ( runFormatBuildFiles    <$> buildFileParser              )
+               (progDesc "Re-Format all build files.")
            )
     )
 
@@ -267,4 +288,3 @@
         <*> (   SharedImageName
             <$> strArgument (help "Shared image name" <> metavar "NAME")
             )
-
diff --git a/src/lib/B9.hs b/src/lib/B9.hs
--- a/src/lib/B9.hs
+++ b/src/lib/B9.hs
@@ -25,25 +25,44 @@
           , runLookupLocalSharedImage
           , module X) where
 import Control.Applicative as X
+import Control.Exception(throwIO, catch)
 import Control.Monad as X
 import Control.Monad.IO.Class as X
-import Control.Exception(throwIO, catch)
+import Control.Monad.Reader as X (ReaderT, local, ask)
+import Control.Lens as X (Lens, (^.), (.~), (%~), (&))
 import System.IO.Error (isDoesNotExistError)
 import System.Directory (removeFile)
-import Data.Monoid as X
+import Data.Function (on)
 import Data.List as X
 import Data.Maybe as X
+import Data.Monoid as X
 import Text.Show.Pretty as X (ppShow)
 import System.Exit as X (exitWith, ExitCode(..))
 import System.FilePath as X
         (takeDirectory, takeFileName, replaceExtension, (</>), (<.>))
 import Text.Printf as X (printf)
 import Data.Version as X
-import B9.Builder as X
-import B9.Invokation as X
+import B9.B9Monad as X
+import Data.ConfigFile.B9Extras as X
+import B9.B9Config as X
+import B9.ExecEnv as X
+import B9.DiskImages as X
+import B9.DiskImageBuilder as X
+import B9.ShellScript as X
+import B9.Repository as X
+import B9.RepositoryIO as X
+import B9.ArtifactGenerator as X
+import B9.ArtifactGeneratorImpl as X
+import B9.Vm as X
+import B9.VmBuilder as X
+import B9.QCUtil as X
+import B9.Content.AST as X
+import B9.Content.StringTemplate as X
+import B9.Content.ErlTerms as X
+import B9.Content.ErlangPropList as X
+import B9.Content.YamlObject as X
+import B9.Content.Generator as X
 import Paths_b9 (version)
-import Data.Function (on)
-import Control.Lens as Lens ((^.), over, (.~), (%~), set)
 
 -- | Return the cabal package version of the B9 library.
 b9Version :: Version
@@ -54,50 +73,61 @@
 b9VersionString :: String
 b9VersionString = showVersion version
 
-runShowVersion :: B9Invokation Bool ()
-runShowVersion = doAfterConfiguration $ const $ do
-  liftIO $ putStrLn b9VersionString
-  return True
+-- | Just print the 'b9VersionString'
+runShowVersion :: MonadIO m => m ()
+runShowVersion = liftIO $ putStrLn b9VersionString
 
-runBuildArtifacts :: [FilePath] -> B9Invokation String ()
+-- | Execute the artifact generators defined in a list of text files.
+-- Read the text files in the list and parse them as 'ArtifactGenerator's
+-- then 'mappend' them and apply 'buildArtifacts' to them.
+runBuildArtifacts :: MonadIO m => [FilePath] -> B9ConfigAction m String
 runBuildArtifacts buildFiles = do
   generators <- mapM consult buildFiles
-  buildArtifacts (mconcat generators)
+  run (buildArtifacts (mconcat generators))
 
-runFormatBuildFiles :: [FilePath] -> B9Invokation Bool ()
-runFormatBuildFiles buildFiles = doAfterConfiguration $ const $ liftIO $ do
+-- | Read all text files and parse them as 'ArtifactGenerator's.
+-- Then overwrite the files with their contents but _pretty printed_
+-- (i.e. formatted).
+runFormatBuildFiles :: MonadIO m => [FilePath] -> m ()
+runFormatBuildFiles buildFiles = liftIO $ do
   generators <- mapM consult buildFiles
   let generatorsFormatted = map ppShow (generators :: [ArtifactGenerator])
-  putStrLn `mapM` (generatorsFormatted)
-  (uncurry writeFile) `mapM` (buildFiles `zip` generatorsFormatted)
-  return True
-
-runPush :: SharedImageName -> B9Invokation Bool ()
-runPush name = do
-  modifyInvokationConfig (keepTempDirs .~ False)
-  run $ const $ do
-    conf <- getConfig
-    if not (isJust (conf ^. repository))
-      then do
-        errorL
-          "No repository specified! Use '-r' to specify a repo BEFORE 'push'."
-        return False
-      else do
-        pushSharedImageLatestVersion name
-        return True
+  putStrLn `mapM` generatorsFormatted
+  zipWithM_ writeFile buildFiles generatorsFormatted
 
+-- | Upload a 'SharedImageName' to the default remote repository.
+-- Note: The remote repository is specified in the 'B9Config'.
+runPush :: MonadIO m => SharedImageName -> B9ConfigAction m ()
+runPush name = localRuntimeConfig (keepTempDirs .~ False) $ run $ do
+  conf <- getConfig
+  if isNothing (conf ^. repository)
+    then
+      errorExitL
+        "No repository specified! Use '-r' to specify a repo BEFORE 'push'."
+    else
+      pushSharedImageLatestVersion name
 
-runPull :: Maybe SharedImageName -> B9Invokation Bool ()
-runPull mName = do
-  modifyInvokationConfig (keepTempDirs .~ False)
-  run (const (pullRemoteRepos >> maybePullImage))
-  where maybePullImage = maybe (return True) pullLatestImage mName
+-- | Either pull a list of available 'SharedImageName's from the remote
+-- repository if 'Nothing' is passed as parameter, or pull the latest version
+-- of the image from the remote repository. Note: The remote repository is
+-- specified in the 'B9Config'.
+runPull :: MonadIO m => Maybe SharedImageName -> B9ConfigAction m ()
+runPull mName =
+  localRuntimeConfig (keepTempDirs .~ False)
+                     (run (pullRemoteRepos >> maybePullImage))
+  where maybePullImage =
+          mapM_ (\name -> pullLatestImage name >>= failIfFalse name) mName
+        failIfFalse _name True =
+          return ()
+        failIfFalse name False =
+          errorExitL (printf "failed to pull: %s" (show name))
 
-runRun :: SharedImageName -> [String] -> B9Invokation String ()
-runRun (SharedImageName name) cmdAndArgs = do
-  modifyInvokationConfig
-    (Lens.set keepTempDirs False . Lens.set interactive True)
-  buildArtifacts runCmdAndArgs
+-- | Execute an interactive root shell in a running container from a
+-- 'SharedImageName'.
+runRun :: MonadIO m => SharedImageName -> [String] -> B9ConfigAction m String
+runRun (SharedImageName name) cmdAndArgs = localRuntimeConfig
+  ((keepTempDirs .~ False) . (interactive .~ True))
+  (run (buildArtifacts runCmdAndArgs))
  where
   runCmdAndArgs = Artifact
     (IID ("run-" ++ name))
@@ -111,28 +141,24 @@
    where
     cmdAndArgs' = if null cmdAndArgs then ["/usr/bin/zsh"] else cmdAndArgs
 
-
-runGcLocalRepoCache :: B9Invokation Bool ()
-runGcLocalRepoCache = do
-  modifyInvokationConfig (keepTempDirs .~ False)
-  impl
+-- | Delete all obsolete versions of all 'SharedImageName's.
+runGcLocalRepoCache :: MonadIO m => B9ConfigAction m ()
+runGcLocalRepoCache = localRuntimeConfig (keepTempDirs .~ False) (run impl)
  where
-  impl = run $ const $ do
-    toDelete <- (obsoleteSharedmages . map snd)
-      <$> lookupSharedImages (== Cache) (const True)
+  impl = do
+    toDelete <- obsoleteSharedmages . map snd <$> lookupSharedImages
+      (== Cache)
+      (const True)
     imgDir <- getSharedImagesCacheDir
     let filesToDelete = (imgDir </>) <$> (infoFiles ++ imgFiles)
         infoFiles     = sharedImageFileName <$> toDelete
-        imgFiles      = (imageFileName . sharedImageImage) <$> toDelete
+        imgFiles      = imageFileName . sharedImageImage <$> toDelete
     if null filesToDelete
-      then liftIO $ do
-        putStrLn "\n\nNO IMAGES TO DELETE\n"
-        return True
+      then liftIO $ putStrLn "\n\nNO IMAGES TO DELETE\n"
       else liftIO $ do
         putStrLn "DELETING FILES:"
         putStrLn (unlines filesToDelete)
         mapM_ removeIfExists filesToDelete
-        return True
   obsoleteSharedmages :: [SharedImage] -> [SharedImage]
   obsoleteSharedmages =
     concatMap (tail . reverse) . filter ((> 1) . length) . groupBy
@@ -143,56 +169,72 @@
     handleExists e | isDoesNotExistError e = return ()
                    | otherwise             = throwIO e
 
-runGcRemoteRepoCache :: B9Invokation Bool ()
-runGcRemoteRepoCache = do
-  modifyInvokationConfig (keepTempDirs .~ False)
-  run $ const $ do
-    repos <- getSelectedRepos
-    cache <- getRepoCache
-    mapM_ (cleanRemoteRepo cache) repos
-    return True
+-- | Clear the shared image cache for a remote. Note: The remote repository is
+-- specified in the 'B9Config'.
+runGcRemoteRepoCache :: MonadIO m => B9ConfigAction m ()
+runGcRemoteRepoCache = localRuntimeConfig
+  (keepTempDirs .~ False)
+  ( run
+    ( do
+      repos <- getSelectedRepos
+      cache <- getRepoCache
+      mapM_ (cleanRemoteRepo cache) repos
+    )
+  )
 
-runListSharedImages :: B9Invokation [SharedImage] ()
-runListSharedImages = do
-  modifyInvokationConfig (keepTempDirs .~ False)
-  run $ const $ do
-    remoteRepo <- getSelectedRemoteRepo
-    let repoPred = maybe (== Cache) ((==) . toRemoteRepository) remoteRepo
-    allRepos <- getRemoteRepos
-    if isNothing remoteRepo
-      then liftIO $ do
-        putStrLn "Showing local shared images only."
-        putStrLn
-          $ "\nTo view the contents of a remote repo add \n\
+-- | Print a list of shared images cached locally or remotely, if a remote
+-- repository was selected. Note: The remote repository is
+-- specified in the 'B9Config'.
+runListSharedImages :: MonadIO m => B9ConfigAction m [SharedImage]
+runListSharedImages = localRuntimeConfig
+  (keepTempDirs .~ False)
+  ( run
+    ( do
+      remoteRepo <- getSelectedRemoteRepo
+      let repoPred = maybe (== Cache) ((==) . toRemoteRepository) remoteRepo
+      allRepos <- getRemoteRepos
+      if isNothing remoteRepo
+        then liftIO $ do
+          putStrLn "Showing local shared images only."
+          putStrLn
+            "\nTo view the contents of a remote repo add \n\
                         \the '-r' switch with one of the remote \n\
                         \repository ids."
-      else liftIO $ putStrLn
-        ("Showing shared images on: " ++ remoteRepoRepoId (fromJust remoteRepo))
-    when (not (null allRepos)) $ liftIO $ do
-      putStrLn "\nAvailable remote repositories:"
-      mapM_ (putStrLn . (" * " ++) . remoteRepoRepoId) allRepos
-    imgs <- lookupSharedImages repoPred (const True)
-    if null imgs
-      then liftIO $ putStrLn "\n\nNO SHARED IMAGES\n"
-      else liftIO $ do
-        putStrLn ""
-        putStrLn $ prettyPrintSharedImages $ map snd imgs
-    return $ map snd imgs
-
+        else liftIO $ putStrLn
+          (  "Showing shared images on: "
+          ++ remoteRepoRepoId (fromJust remoteRepo)
+          )
+      unless (null allRepos) $ liftIO $ do
+        putStrLn "\nAvailable remote repositories:"
+        mapM_ (putStrLn . (" * " ++) . remoteRepoRepoId) allRepos
+      imgs <- lookupSharedImages repoPred (const True)
+      if null imgs
+        then liftIO $ putStrLn "\n\nNO SHARED IMAGES\n"
+        else liftIO $ do
+          putStrLn ""
+          putStrLn $ prettyPrintSharedImages $ map snd imgs
+      return (map snd imgs)
+    )
+  )
 
-runAddRepo :: RemoteRepo -> B9Invokation Bool ()
+-- | Check the SSH settings for a remote repository and add it to the user wide
+-- B9 configuration file.
+runAddRepo :: MonadIO m => RemoteRepo -> B9ConfigAction m ()
 runAddRepo repo = do
   repo' <- remoteRepoCheckSshPrivKey repo
   modifyPermanentConfig
-    (  remoteRepos
-    %~ ( mappend [repo']
-       . filter ((== remoteRepoRepoId repo') . remoteRepoRepoId)
-       )
+    ( Endo
+      (  remoteRepos
+      %~ ( mappend [repo']
+         . filter ((== remoteRepoRepoId repo') . remoteRepoRepoId)
+         )
+      )
     )
 
+-- | Find the most recent version of a 'SharedImageName' in the local image cache.
 runLookupLocalSharedImage
-  :: SharedImageName -> B9Invokation (Maybe SharedImageBuildId) ()
-runLookupLocalSharedImage n = run $ const $ do
+  :: MonadIO m => SharedImageName -> B9ConfigAction m (Maybe SharedImageBuildId)
+runLookupLocalSharedImage n = run $ do
   traceL (printf "Searching for cached image: %s" (show n))
   imgs <- lookupSharedImages isAvailableOnLocalHost hasTheDesiredName
   traceL "Candidate images: "
diff --git a/src/lib/B9/ArtifactGeneratorImpl.hs b/src/lib/B9/ArtifactGeneratorImpl.hs
--- a/src/lib/B9/ArtifactGeneratorImpl.hs
+++ b/src/lib/B9/ArtifactGeneratorImpl.hs
@@ -13,7 +13,6 @@
 import B9.Content.StringTemplate
 import B9.Content.Generator
 import B9.Content.AST
-
 import qualified Data.ByteString as B
 import qualified Data.Text as T
 import qualified Data.Text.Encoding as E
@@ -32,6 +31,16 @@
 import System.Directory
 import Text.Printf
 import Text.Show.Pretty (ppShow)
+
+-- | Execute an 'ArtifactGenerator' and return a 'B9Invokation' that returns
+-- the build id obtained by 'getBuildId'.
+buildArtifacts :: ArtifactGenerator -> B9 String
+buildArtifacts artifactGenerator = do
+  traceL . ("CWD: " ++) =<< liftIO getCurrentDirectory
+  infoL "BUILDING ARTIFACTS"
+  getConfig >>= traceL . printf "USING BUILD CONFIGURATION: %v" . ppShow
+  assemble artifactGenerator
+  getBuildId
 
 -- | Return a list of relative paths for the /local/ files to be generated
 -- by the ArtifactGenerator. This excludes 'Shared' and Transient image targets.
diff --git a/src/lib/B9/B9Config.hs b/src/lib/B9/B9Config.hs
--- a/src/lib/B9/B9Config.hs
+++ b/src/lib/B9/B9Config.hs
@@ -17,8 +17,20 @@
                    , libVirtLXCConfigs
                    , remoteRepos
                    , B9ConfigOverride(..)
+                   , noB9ConfigOverride
+                   , B9ConfigAction()
+                   , execB9ConfigAction
+                   , invokeB9
+                   , askRuntimeConfig
+                   , localRuntimeConfig
+                   , modifyPermanentConfig
                    , customB9Config
                    , customB9ConfigPath
+                   , overrideB9ConfigPath
+                   , overrideB9Config
+                   , overrideWorkingDirectory
+                   , overrideVerbosity
+                   , overrideKeepBuildDirs
                    , defaultB9ConfigFile
                    , defaultRepositoryCache
                    , defaultB9Config
@@ -38,16 +50,22 @@
 import Data.Maybe (fromMaybe)
 import Control.Exception
 import Data.Function (on)
+import Control.Lens as Lens (makeLenses, (^.), (.~), over, set)
+import Control.Monad ((>=>))
 import Control.Monad.IO.Class
+import Control.Monad.Reader
+import Control.Monad.Writer
 import System.Directory
 import qualified Data.Semigroup as Sem
-import Data.Monoid
 import Data.List (partition, sortBy)
 import Data.ConfigFile.B9Extras
+          ( SystemPath(..), ConfigParser, CPError, Get_C
+          , OptionSpec, resolve, ensureDir, readIniFile
+          , IniFileException(..), merge, to_string
+          , add_section, emptyCP, setshow, get)
 import B9.B9Config.LibVirtLXC as X
 import B9.B9Config.Repository as X
-import Control.Lens.TH
-import Control.Monad ((>=>))
+import Text.Printf (printf)
 
 type BuildVariables = [(String,String)]
 
@@ -98,11 +116,116 @@
 data B9ConfigOverride = B9ConfigOverride
   { _customB9ConfigPath :: Maybe SystemPath
   , _customB9Config     :: B9Config
-  }
+  } deriving Show
 
+-- | An empty default 'B9ConfigOverride' value, that will neither apply any
+-- additional 'B9Config' nor change the path of the configuration file.
+noB9ConfigOverride :: B9ConfigOverride
+noB9ConfigOverride = B9ConfigOverride Nothing mempty
+
 makeLenses ''B9Config
 makeLenses ''B9ConfigOverride
 
+-- | Convenience utility to override the B9 configuration file path.
+overrideB9ConfigPath :: SystemPath -> B9ConfigOverride -> B9ConfigOverride
+overrideB9ConfigPath p = customB9ConfigPath .~ Just p
+
+-- | Modify the runtime configuration.
+overrideB9Config
+  :: (B9Config -> B9Config) -> B9ConfigOverride -> B9ConfigOverride
+overrideB9Config = over customB9Config
+
+-- | Define the current working directory to be used when building.
+overrideWorkingDirectory :: FilePath -> B9ConfigOverride -> B9ConfigOverride
+overrideWorkingDirectory p = customB9Config . buildDirRoot .~ Just p
+
+
+-- | Overwrite the 'verbosity' settings in the configuration with those given.
+overrideVerbosity :: LogLevel -> B9ConfigOverride -> B9ConfigOverride
+overrideVerbosity = overrideB9Config . Lens.set verbosity . Just
+
+-- | Overwrite the 'keepTempDirs' flag in the configuration with those given.
+overrideKeepBuildDirs :: Bool -> B9ConfigOverride -> B9ConfigOverride
+overrideKeepBuildDirs = overrideB9Config . Lens.set keepTempDirs
+
+-- | A monad that gives access to the (transient) 'B9Config' to be used to
+-- _runtime_ with 'askRuntimeConfig' or 'localRuntimeConfig', and that allows
+-- to write permanent 'B9Config' changes back to the configuration file using
+-- 'modifyPermanentConfig'. Execute a 'B9ConfigAction' by invoking
+-- either 'invokeB9' (which is simple) or 'execB9ConfigAction'.
+newtype B9ConfigAction m a = B9ConfigAction
+  { runB9ConfigAction :: ReaderT B9Config (WriterT [Endo B9Config] m) a}
+  deriving ( Functor, Applicative, Monad, MonadIO )
+
+-- | Return the runtime configuration, that should be the configuration merged
+-- from all configuration sources. This is the configuration to be used during
+-- a VM image build.
+askRuntimeConfig :: Monad m => B9ConfigAction m B9Config
+askRuntimeConfig = B9ConfigAction ask
+
+-- | Run an action with an updated runtime configuration.
+localRuntimeConfig
+  :: Monad m
+  => (B9Config -> B9Config)
+  -> B9ConfigAction m a
+  -> B9ConfigAction m a
+localRuntimeConfig f = B9ConfigAction . local f . runB9ConfigAction
+
+-- | Add a modification to the permanent configuration file.
+modifyPermanentConfig :: Monad m => Endo B9Config -> B9ConfigAction m ()
+modifyPermanentConfig f = B9ConfigAction (tell [f])
+
+-- | Execute a 'B9ConfigAction'.
+-- It will take a 'B9ConfigOverride' as input. The 'B9Config' in that value is
+-- treated as the _runtime_ configuration, and the '_customConfigPath' is used
+-- as the alternative location of the configuration file.
+-- The configuration file is read from either the path in '_customB9ConfigPath'
+-- or from 'defaultB9ConfigFile'.
+-- Every modification done via 'modifyPermanentConfig' is applied to
+-- the **contents** of the configuration file
+-- and written back to that file, note that these changes are ONLY reflected
+-- in the configuration file and **not** in the _runtime configuration_.
+--
+-- See also 'invokeB9', which does not need the 'B9ConfigOverride' parameter.
+execB9ConfigAction :: MonadIO m => B9ConfigAction m a -> B9ConfigOverride -> m a
+execB9ConfigAction act cfg = do
+  let cfgPath = cfg ^. customB9ConfigPath
+  cp <- openOrCreateB9Config cfgPath
+
+  case parseB9Config cp of
+    Left e -> do
+      fail
+        ( printf "Internal configuration load error, please report this: %s\n"
+                 (show e)
+        )
+
+    Right permanentConfig -> do
+      let runtimeCfg = permanentConfig Sem.<> (cfg ^. customB9Config)
+      (res, permanentB9ConfigUpdates) <- runWriterT
+        (runReaderT (runB9ConfigAction act) runtimeCfg)
+
+      let cpExtErr = modifyConfigParser cp <$> permanentB9ConfigUpdate
+          permanentB9ConfigUpdate = if null permanentB9ConfigUpdates
+            then Nothing
+            else Just (mconcat permanentB9ConfigUpdates)
+      cpExt <- maybe
+        (return Nothing)
+        ( either
+          ( fail
+          . printf
+              "Internal configuration update error! Please report this: %s\n"
+          . show
+          )
+          (return . Just)
+        )
+        cpExtErr
+      mapM_ (writeB9ConfigParser (cfg ^. customB9ConfigPath)) cpExt
+      return res
+-- | Run a 'B9ConfigAction' using 'noB9ConfigOverride'.
+-- See 'execB9ConfigAction' for more details.
+invokeB9 :: MonadIO m => B9ConfigAction m a -> m a
+invokeB9 = flip execB9ConfigAction noB9ConfigOverride
+
 -- | Open the configuration file that contains the 'B9Config'.
 -- If the configuration does not exist, write a default configuration file,
 -- and create a all missing directories.
@@ -115,7 +238,7 @@
     if exists
       then readIniFile (Path cfgFile)
       else
-        let res = b9ConfigToConfigParser defaultB9Config emptyCP
+        let res = b9ConfigToConfigParser defaultB9Config
         in  case res of
               Left  e  -> throwIO (IniFileException cfgFile e)
               Right cp -> writeFile cfgFile (to_string cp) >> return cp
@@ -176,17 +299,16 @@
 
 -- | Parse a 'B9Config', modify it, and merge it back to the given 'ConfigParser'.
 modifyConfigParser
-  :: (B9Config -> B9Config) -> ConfigParser -> Either CPError ConfigParser
-modifyConfigParser f cp = do
+  :: ConfigParser -> Endo B9Config -> Either CPError ConfigParser
+modifyConfigParser cp f = do
   cfg <- parseB9Config cp
-  cp2 <- b9ConfigToConfigParser (f cfg) emptyCP
+  cp2 <- b9ConfigToConfigParser (appEndo f cfg)
   return (merge cp cp2)
 
--- | Append a config file section for the 'B9Config' to a 'ConfigParser'.
-b9ConfigToConfigParser
-  :: B9Config -> ConfigParser -> Either CPError ConfigParser
-b9ConfigToConfigParser c cp = do
-  cp1 <- add_section cp cfgFileSection
+-- | Append a config file section for the 'B9Config' to an empty 'ConfigParser'.
+b9ConfigToConfigParser :: B9Config -> Either CPError ConfigParser
+b9ConfigToConfigParser c = do
+  cp1 <- add_section emptyCP cfgFileSection
   cp2 <- setshow cp1 cfgFileSection verbosityK (_verbosity c)
   cp3 <- setshow cp2 cfgFileSection logFileK (_logFile c)
   cp4 <- setshow cp3 cfgFileSection buildDirRootK (_buildDirRoot c)
diff --git a/src/lib/B9/B9Monad.hs b/src/lib/B9/B9Monad.hs
--- a/src/lib/B9/B9Monad.hs
+++ b/src/lib/B9/B9Monad.hs
@@ -7,20 +7,18 @@
 This module is used by the _effectful_ functions in this library.
 -}
 module B9.B9Monad
-       (B9, run, traceL, dbgL, infoL, errorL, getConfig,
+       (B9, run, traceL, dbgL, infoL, errorL, errorExitL, getConfig,
         getBuildId, getBuildDate, getBuildDir, getExecEnvType,
         getSelectedRemoteRepo, getRemoteRepos, getRepoCache, cmd)
        where
 
 import B9.B9Config
-import B9.Invokation
 import B9.Repository
 import Control.Applicative
 import Control.Exception (bracket)
 import Control.Monad
 import Control.Monad.IO.Class
 import Control.Monad.State
-import Control.Monad.Reader(ask)
 import Control.Lens((&), (.~))
 import qualified Data.ByteString.Char8 as B
 import Data.Functor ()
@@ -57,14 +55,14 @@
              String
   deriving (Eq,Show)
 
-run :: (Maybe a -> B9 a) -> B9Invokation a ()
-run actionFunction = doAfterConfiguration $ \previousResult -> do
-  cfg <- ask
+
+run :: MonadIO m => B9 a -> B9ConfigAction m a
+run action = do
+  cfg <- askRuntimeConfig
   liftIO $ do
     buildId <- generateBuildId
     now     <- getCurrentTime
-    let action = actionFunction previousResult
-    withBuildDir cfg buildId (withLogFile cfg . runImpl action cfg buildId now)
+    withBuildDir cfg buildId (withLogFile cfg . runImpl cfg buildId now)
  where
   withLogFile cfg f = maybe
     (f Nothing)
@@ -72,38 +70,39 @@
     (_logFile cfg)
   withBuildDir cfg buildId =
     bracket (createBuildDir cfg buildId) (removeBuildDir cfg)
-  runImpl action cfg buildId now buildDir logFileHandle = do
-    maybe (return ()) setCurrentDirectory (_buildDirRoot cfg)
-    -- Check repositories
-    repoCache <- initRepoCache
-      (fromMaybe defaultRepositoryCache (_repositoryCache cfg))
-    let buildDate = formatTime undefined "%F-%T" now
-    remoteRepos' <- mapM (initRemoteRepo repoCache) (_remoteRepos cfg)
-    let
-      ctx = BuildState buildId
-                       buildDate
-                       (cfg & remoteRepos .~ remoteRepos')
-                       buildDir
-                       logFileHandle
-                       selectedRemoteRepo
-                       repoCache
-                       []
-                       now
-                       (_interactive cfg)
-      selectedRemoteRepo = do
-        sel <- _repository cfg
-        lookupRemoteRepo remoteRepos' sel <|> error
-          ( printf
-            "selected remote repo '%s' not configured, valid remote repos are: '%s'"
-            sel
-            (show remoteRepos')
-          )
-    (r, ctxOut) <- runStateT (runB9 (wrappedAction action)) ctx
-    -- Write a profiling report
-    when (isJust (_profileFile cfg)) $ writeFile
-      (fromJust (_profileFile cfg))
-      (unlines $ show <$> reverse (bsProf ctxOut))
-    return r
+  runImpl cfg buildId now buildDir logFileHandle =
+    bracket getCurrentDirectory setCurrentDirectory $ \_ -> do
+      traverse setCurrentDirectory (_buildDirRoot cfg)
+      -- Check repositories
+      repoCache <- initRepoCache
+        (fromMaybe defaultRepositoryCache (_repositoryCache cfg))
+      let buildDate = formatTime undefined "%F-%T" now
+      remoteRepos' <- mapM (initRemoteRepo repoCache) (_remoteRepos cfg)
+      let
+        ctx = BuildState buildId
+                         buildDate
+                         (cfg & remoteRepos .~ remoteRepos')
+                         buildDir
+                         logFileHandle
+                         selectedRemoteRepo
+                         repoCache
+                         []
+                         now
+                         (_interactive cfg)
+        selectedRemoteRepo = do
+          sel <- _repository cfg
+          lookupRemoteRepo remoteRepos' sel <|> error
+            ( printf
+              "selected remote repo '%s' not configured, valid remote repos are: '%s'"
+              sel
+              (show remoteRepos')
+            )
+      (r, ctxOut) <- runStateT (runB9 wrappedAction) ctx
+      -- Write a profiling report
+      when (isJust (_profileFile cfg)) $ writeFile
+        (fromJust (_profileFile cfg))
+        (unlines $ show <$> reverse (bsProf ctxOut))
+      return r
   createBuildDir cfg buildId = if _uniqueBuildDirs cfg
     then do
       let subDir = "BUILD-" ++ buildId
@@ -127,7 +126,7 @@
       $ removeDirectoryRecursive buildDir
   generateBuildId = printf "%08X" <$> (randomIO :: IO Word32)
   -- Run the action build action
-  wrappedAction action = do
+  wrappedAction = do
     startTime <- gets bsStartTime
     r         <- action
     now       <- liftIO getCurrentTime
@@ -226,6 +225,9 @@
 errorL :: String -> B9 ()
 errorL = b9Log LogError
 
+errorExitL :: String -> B9 ()
+errorExitL e = b9Log LogError e >> fail e
+
 b9Log :: LogLevel -> String -> B9 ()
 b9Log level msg = do
   lv  <- gets $ _verbosity . bsCfg
@@ -267,13 +269,3 @@
        let durMS = IoActionDuration (stop `diffUTCTime` start)
        modify $ \ctx -> ctx {bsProf = durMS : bsProf ctx}
        return res
-
-
-
-
-
-
-
-
-
-
diff --git a/src/lib/B9/Builder.hs b/src/lib/B9/Builder.hs
deleted file mode 100644
--- a/src/lib/B9/Builder.hs
+++ /dev/null
@@ -1,41 +0,0 @@
-{-# LANGUAGE GADTs #-}
-{-|
-Highest-level build functions and and B9-re-exports.
--}
-module B9.Builder (buildArtifacts, module X) where
-import B9.B9Monad as X
-import Data.ConfigFile.B9Extras as X
-import B9.B9Config as X
-import B9.ExecEnv as X
-import B9.DiskImages as X
-import B9.DiskImageBuilder as X
-import B9.Invokation as X
-import B9.ShellScript as X
-import B9.Repository as X
-import B9.RepositoryIO as X
-import B9.ArtifactGenerator as X
-import B9.ArtifactGeneratorImpl as X
-import B9.Vm as X
-import B9.VmBuilder as X
-import B9.QCUtil as X
-import B9.Content.AST as X
-import B9.Content.StringTemplate as X
-import B9.Content.ErlTerms as X
-import B9.Content.ErlangPropList as X
-import B9.Content.YamlObject as X
-import B9.Content.Generator as X
-
-import Text.Printf ( printf )
-import Text.Show.Pretty (ppShow)
-import Control.Monad.IO.Class
-import System.Directory
-
--- | Execute an 'ArtifactGenerator' and return a 'B9Invokation' that returns
--- the build id obtained by 'getBuildId'.
-buildArtifacts :: ArtifactGenerator -> B9Invokation String ()
-buildArtifacts artifactGenerator = run $ const $ do
-  traceL . ("CWD: " ++) =<< liftIO getCurrentDirectory
-  infoL "BUILDING ARTIFACTS"
-  getConfig >>= traceL . printf "USING BUILD CONFIGURATION: %v" . ppShow
-  assemble artifactGenerator
-  getBuildId
diff --git a/src/lib/B9/Content/YamlObject.hs b/src/lib/B9/Content/YamlObject.hs
--- a/src/lib/B9/Content/YamlObject.hs
+++ b/src/lib/B9/Content/YamlObject.hs
@@ -28,18 +28,17 @@
 -- | A wrapper type around yaml values with a Semigroup instance useful for
 -- combining yaml documents describing system configuration like e.g. user-data.
 data YamlObject =
-    YamlObject Data.Yaml.Value
+    YamlObject {_fromYamlObject :: Data.Yaml.Value}
     deriving (Eq,Data,Typeable,Generic)
 
 instance Hashable YamlObject
-instance Binary YamlObject
 instance NFData YamlObject
 
-instance Binary Data.Yaml.Value where
-  put = put . encode
+instance Binary YamlObject where
+  put = put . encode . _fromYamlObject
   get = do
     v <- get
-    return $ fromJust $ decode v
+    return $ YamlObject $ fromJust $ decode v
 
 instance Read YamlObject where
   readsPrec _ = readsYamlObject
diff --git a/src/lib/B9/Invokation.hs b/src/lib/B9/Invokation.hs
deleted file mode 100644
--- a/src/lib/B9/Invokation.hs
+++ /dev/null
@@ -1,161 +0,0 @@
-module B9.Invokation ( B9Invokation()
-                     , invokeB9
-                     , overrideWorkingDirectory
-                     , mergeAfterConfigurationActionResults
-                     , ignoreActionResults
-                     , doAfterConfiguration
-                     , overrideB9ConfigPath
-                     , modifyInvokationConfig
-                     , modifyPermanentConfig) where
-
-import B9.B9Config
-import Data.ConfigFile.B9Extras
-import Control.Monad.IO.Class
-import Control.Monad.State
-import Control.Monad.Reader
-import Control.Lens
-import Control.Exception (bracket)
-import System.Directory (getCurrentDirectory, setCurrentDirectory)
-import Data.Semigroup as Sem
-import Data.Maybe (fromMaybe)
-import Text.Printf ( printf )
-
--- | A monad encapsulating all configuration adaptions happening before any actual
--- build actions are performed. Use 'invokeB9' to execute these things.
--- Inside the 'B9Invokation' monad you can influence and inspect the b9
--- configuration, the permanent, as well as the transient.
-newtype B9Invokation res a = B9Inv {runB9Invokation :: StateT (InternalState res) IO a}
-  deriving (MonadState (InternalState res), Monad, Applicative, Functor, MonadIO)
-
--- | Internal state of the 'B9Invokation'
-data InternalState a = IS { _initialConfigOverride   :: B9ConfigOverride
-                          , _permanentB9ConfigUpdate :: Maybe (ConfigParser -> Either CPError ConfigParser)
-                          , _changeWorkingDirectory  :: Maybe FilePath
-                          , _buildAction             :: Maybe (ReaderT B9Config IO a)
-                          }
-
-makeLenses ''InternalState
-
-initialState :: InternalState a
-initialState = IS (B9ConfigOverride Nothing mempty) Nothing Nothing Nothing
-
--- | Run a 'B9Invokation'.
--- If the user has no B9 config file yet, a default config file will be created.
-invokeB9 :: B9Invokation res () -> IO (Maybe res)
-invokeB9 act = do
-    st <- execStateT (runB9Invokation act) initialState
-    let cfgPath = st ^. initialConfigOverride . customB9ConfigPath
-    cp0 <- openOrCreateB9Config cfgPath
-    let cpExtErr = fmap ($ cp0) (st ^. permanentB9ConfigUpdate)
-    cpExt <- maybe
-        (return Nothing)
-        ( either
-            ( fail
-            . printf "Internal configuration error! Please report this: %s\n"
-            . show
-            )
-            (return . Just)
-        )
-        cpExtErr
-    let cp = fromMaybe cp0 cpExt
-    mapM_ (writeB9ConfigParser cfgPath) cpExt
-    case parseB9Config cp of
-        Left e -> fail (printf "Configuration error: %s\n" (show e))
-        Right permanentConfig -> do
-            let
-                runtimeCfg =
-                    permanentConfig
-                        Sem.<> st
-                        ^.     initialConfigOverride
-                        .      customB9Config
-                completeBuildAction = bracket
-                    getCurrentDirectory
-                    setCurrentDirectory
-                    ( const
-                        ( do
-                            mapM_ setCurrentDirectory
-                                  (st ^. changeWorkingDirectory)
-                            runReaderT (sequence (st ^. buildAction)) runtimeCfg
-                        )
-                    )
-            completeBuildAction
-
--- | Add an action to be executed once the configuration has been done.
--- The action will be called with the result of the previous action defined by
--- this function. In case this is the first action added 'Nothing' is passed.
-doAfterConfiguration :: (Maybe a -> ReaderT B9Config IO a) -> B9Invokation a ()
-doAfterConfiguration action = buildAction %= appendOrSet
-  where
-    appendOrSet Nothing  = Just (action Nothing)
-    appendOrSet (Just x) = Just (x >>= action . Just)
-
--- | Combine the result of a given 'B9Invokation' and the results of the action
--- defined by 'doAfterConfiguration' in the current state.
-mergeAfterConfigurationActionResults
-    :: (Maybe a -> Maybe b -> ReaderT B9Config IO b)
-    -> B9Invokation a ()
-    -> B9Invokation b ()
-mergeAfterConfigurationActionResults f ba = do
-    st <- liftIO $ execStateT (runB9Invokation ba) initialState
-    let fb mbAction = Just $ do
-            ma <- sequence (st ^. buildAction)
-            mb <- sequence mbAction
-            f ma mb
-    buildAction %= fb
-
--- | Ignore the results of the actions defined by 'doAfterConfiguration'.
--- All actions will be executed, but the result will be replaced with '()'.
-ignoreActionResults :: B9Invokation a () -> B9Invokation () ()
-ignoreActionResults =
-    mergeAfterConfigurationActionResults (const (const (return ())))
-
--- | Override the B9 configuration path
-overrideB9ConfigPath :: SystemPath -> B9Invokation a ()
-overrideB9ConfigPath p = initialConfigOverride . customB9ConfigPath .= Just p
-
--- | Override the current working directory during execution of the actions
--- added with 'doAfterConfiguration'.
-overrideWorkingDirectory :: FilePath -> B9Invokation a ()
-overrideWorkingDirectory p = changeWorkingDirectory .= Just p
-
--- | Modify the current 'B9Config'. The modifications are not reflected in the
--- config file or the 'ConfigParser' returned by 'askInvokationConfigParser'.
-modifyInvokationConfig :: (B9Config -> B9Config) -> B9Invokation a ()
-modifyInvokationConfig f = initialConfigOverride . customB9Config %= f
-
--- | Modify the current 'B9Config'. The modifications are not reflected in the
--- config file or the 'ConfigParser' returned by 'askInvokationConfigParser'.
-modifyPermanentConfig :: (B9Config -> B9Config) -> B9Invokation a ()
-modifyPermanentConfig g = permanentB9ConfigUpdate %= go
-  where
-    go Nothing  = go (Just return)
-    go (Just f) = Just (\cp -> f cp >>= modifyConfigParser g)
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
diff --git a/src/lib/B9/Shake/Actions.hs b/src/lib/B9/Shake/Actions.hs
--- a/src/lib/B9/Shake/Actions.hs
+++ b/src/lib/B9/Shake/Actions.hs
@@ -5,11 +5,11 @@
 import Development.Shake.FilePath
 import B9
 
--- | Convert a 'B9Invokation' action into a Shake 'Action'.
-b9InvokationAction :: B9Invokation a () -> Action a
-b9InvokationAction invokationAction = do
-    mres <- liftIO (invokeB9 invokationAction)
-    maybe (fail "ERROR: Internal error while invoking a b9 action!") return mres
+-- | Convert a 'B9Invokation' action into a Shake 'Action'. This is just
+-- an alias for 'execB9ConfigAction' since 'Action' is an instance of 'MonadIO'
+-- and 'execB9ConfigAction' work on any .
+b9InvokationAction :: B9ConfigAction Action a -> B9ConfigOverride -> Action a
+b9InvokationAction = execB9ConfigAction
 
 -- | An action that does the equivalent of
 -- @b9c build -f <b9file> -- (args !! 0) (args !! 1) ... (args !! (length args - 1))@
@@ -19,7 +19,8 @@
 buildB9File b9Root b9File args = do
     let f = b9Root </> b9File
     need [f]
-    b9InvokationAction $ do
-        modifyInvokationConfig (appendPositionalArguments args)
-        overrideWorkingDirectory b9Root
-        runBuildArtifacts [f]
+    invokeB9
+        ( localRuntimeConfig
+            (appendPositionalArguments args . (buildDirRoot .~ Just b9Root))
+            (runBuildArtifacts [f])
+        )
diff --git a/src/lib/B9/Shake/SharedImageRules.hs b/src/lib/B9/Shake/SharedImageRules.hs
--- a/src/lib/B9/Shake/SharedImageRules.hs
+++ b/src/lib/B9/Shake/SharedImageRules.hs
@@ -11,12 +11,11 @@
 import qualified Data.ByteString.Lazy as LazyByteString
 import qualified Data.Binary as Binary
 import B9
-import B9.Shake.Actions (b9InvokationAction)
 
 -- | In order to use 'needSharedImage' and 'customSharedImageAction' you need to
 -- call this action before using any of the afore mentioned.
-enableSharedImageRules :: Rules ()
-enableSharedImageRules = addBuiltinRule noLint go
+enableSharedImageRules :: B9ConfigOverride -> Rules ()
+enableSharedImageRules b9inv = addBuiltinRule noLint go
  where
   go :: SharedImageName
      -> Maybe ByteString.ByteString
@@ -49,7 +48,7 @@
               result = RunResult change newBuildIdBin newBuildId
           return result
     where
-      getImgBuildId = b9InvokationAction (runLookupLocalSharedImage nameQ)
+      getImgBuildId = execB9ConfigAction (runLookupLocalSharedImage nameQ) b9inv
 
       decodeBuildId :: ByteString.ByteString -> SharedImageBuildId
       decodeBuildId = Binary.decode . LazyByteString.fromStrict
@@ -62,7 +61,7 @@
         rules <- getUserRules
         case userRuleMatch rules imgMatch of
           [] -> fail $ "No rules to build B9 shared image " ++ show nameQ ++ " found"
-          [act] -> act
+          [act] -> act b9inv
           _rs  -> fail $ "Multiple rules for the B9 shared image " ++ show nameQ ++ " found"
         where
           imgMatch (SharedImageCustomActionRule name mkImage) =
@@ -81,9 +80,9 @@
 customSharedImageAction b9img customAction =
   addUserRule (SharedImageCustomActionRule b9img customAction')
   where
-    customAction' = do
+    customAction' b9inv = do
       customAction
-      mCurrentBuildId <- b9InvokationAction (runLookupLocalSharedImage b9img)
+      mCurrentBuildId <- execB9ConfigAction (runLookupLocalSharedImage b9img) b9inv
       putLoud (printf "Finished custom action, for %s, build-id is: %s"
                       (show b9img) (show mCurrentBuildId))
       maybe (errorSharedImageNotFound b9img) return mCurrentBuildId
@@ -92,7 +91,7 @@
 type instance RuleResult SharedImageName = SharedImageBuildId
 
 data SharedImageCustomActionRule =
-  SharedImageCustomActionRule SharedImageName (Action SharedImageBuildId)
+  SharedImageCustomActionRule SharedImageName (B9ConfigOverride -> Action SharedImageBuildId)
   deriving Typeable
 
 errorSharedImageNotFound :: Monad m => SharedImageName -> m a
diff --git a/stack.yaml b/stack.yaml
--- a/stack.yaml
+++ b/stack.yaml
@@ -2,6 +2,7 @@
 packages:
 - '.'
 extra-deps: []
-resolver: lts-11.0
+resolver: lts-11.3
 allow-newer: true
 # pvp-bounds: lower
+require-stack-version: ">=1.6.5"