Merge branch 'runtime-flags': runtime handler toggling

default.nix

@@ -1,8 +1,8 @@
 { mkDerivation, aeson, annotated-exception, async, base, bytestring
 , cereal, cereal-conduit, conduit, containers, directory, ekg-core
-, exceptions, filepath, hedgehog, hspec, hspec-hedgehog, http-types
-, katip, lens, lens-aeson, lib, network, process, retry, scotty
-, servant, servant-server, stm, text, time, unliftio
+, exceptions, filepath, hedgehog, hspec, hspec-hedgehog, http-media
+, http-types, katip, lens, lens-aeson, lib, network, process, retry
+, servant, servant-server, stm, temporary, text, time, unliftio
 , unordered-containers, uuid, wai, warp, websockets
 }:
 mkDerivation {
@@ -14,15 +14,15 @@ mkDerivation {
   libraryHaskellDepends = [
     aeson annotated-exception async base bytestring cereal
     cereal-conduit conduit containers directory ekg-core exceptions
-    filepath http-types katip lens lens-aeson network process retry
-    scotty servant servant-server stm text time unliftio
+    filepath http-media http-types katip lens lens-aeson network
+    process retry servant servant-server stm text time unliftio
     unordered-containers uuid wai warp websockets
   ];
   executableHaskellDepends = [ base ];
   testHaskellDepends = [
     aeson annotated-exception async base bytestring cereal containers
-    directory ekg-core hedgehog hspec hspec-hedgehog katip process stm
-    text time unordered-containers uuid
+    directory ekg-core hedgehog hspec hspec-hedgehog katip process
+    servant stm temporary text time unordered-containers uuid
   ];
   license = lib.meta.getLicenseFromSpdxId "BSD-3-Clause";
   mainProgram = "home-assistant-controller";

home-assistant-controller.cabal

@@ -70,6 +70,7 @@ library
                     , HomeAssistant.Runtime
                     , HomeAssistant.Runtime.Bus
                     , HomeAssistant.Runtime.Connection
+                    , HomeAssistant.Runtime.Flags
                     , HomeAssistant.Runtime.Graphing
                     , HomeAssistant.Runtime.Metrics
                     , HomeAssistant.Runtime.Supervisor
@@ -161,6 +162,7 @@ test-suite home-assistant-controller-test
                     , BedroomSpec
                     , BusSpec
                     , ConnectionSpec
+                    , FlagsSpec
                     , GraphingSpec
                     , MetricsSpec
                     , RuntimeSpec
@@ -200,4 +202,5 @@ test-suite home-assistant-controller-test
         ekg-core,
         unordered-containers,
         process,
-        directory
+        directory,
+        temporary

src/AFRP.hs

@@ -106,6 +106,7 @@ data Request = Request
   { requestTime     :: !UTCTime
   , requestTimeZone  :: !TimeZone
   , requestTraceId  :: !UUID
+  , requestHandler  :: !T.Text
   } deriving (Show, Eq)
 
 

src/HomeAssistant/Runtime.hs

@@ -21,6 +21,7 @@ import Data.Time (getCurrentTime, getCurrentTimeZone)
 import Data.Void (Void)
 import HomeAssistant.Controller (HASS, HASSEff (..))
 import HomeAssistant.Runtime.Bus
+import HomeAssistant.Runtime.Flags (loadFlags)
 import HomeAssistant.Runtime.Connection (writerAction, readerAction)
 import Network.Socket (withSocketsDo)
 import System.Environment (getEnv, lookupEnv)
@@ -43,34 +44,34 @@ import HomeAssistant.Runtime.Supervisor (supervised)
 import HomeAssistant.Controller.Hallway (hallwayLightsController)
 import qualified HttpServer
 
-step :: (MonadIO m) => FilePath -> UUID -> Auto m a b -> a -> m (b, Auto m a b)
-step path trace st a = do
+step :: (MonadIO m) => FilePath -> T.Text -> UUID -> Auto m a b -> a -> m (b, Auto m a b)
+step path name trace st a = do
   now <- liftIO getCurrentTime
   tz <- liftIO getCurrentTimeZone
-  let req = Request now tz trace
+  let req = Request now tz trace name
   stepAutoSerializing path st req a
 
-data Controller = forall b. Controller Bool T.Text (HASS (Event Value) b)
+data Controller = forall b. Controller T.Text (HASS (Event Value) b)
 
 controllers :: [Controller]
 controllers =
-  [ Controller True "bedroom-presence" bedroomPresenceController
-  , Controller True "bedroom-button" bedroomButtonController
-  , Controller True "bedroom-drawer" bedroomDrawerController
-  , Controller True "bedroom-humidifier" humidifierController
-  , Controller True "school-light-controller" schoolLightController
-  , Controller True "kitchen-motion-controller" kitchenMotionController
-  , Controller True "livingroom-presence" livingroomPresenceController
-  , Controller True "hallway-motion-controller" hallwayLightsController
-  , Controller True "children-button" childrenBedroomButtonController
-  , Controller True "livingroom-plants" livingroomPlantLights
+  [ Controller "bedroom-presence" bedroomPresenceController
+  , Controller "bedroom-button" bedroomButtonController
+  , Controller "bedroom-drawer" bedroomDrawerController
+  , Controller "bedroom-humidifier" humidifierController
+  , Controller "school-light-controller" schoolLightController
+  , Controller "kitchen-motion-controller" kitchenMotionController
+  , Controller "livingroom-presence" livingroomPresenceController
+  , Controller "hallway-motion-controller" hallwayLightsController
+  , Controller "children-button" childrenBedroomButtonController
+  , Controller "livingroom-plants" livingroomPlantLights
   ]
 
 -- | Steps the machine for every inbound message; service calls go to the
 -- bus. A restart re-dups the inbound channel and starts from the machine's
 -- initial state; messages broadcast during the restart window are lost.
 runController :: MonadIO m => FilePath -> Bus -> Controller -> m Void
-runController rootDir bus (Controller _enabled name machine ) = liftIO $ do
+runController rootDir bus (Controller name machine ) = liftIO $ do
   inbound <- atomically (dupTChan (busInbound bus))
   let ns = Namespace [name]
   let workerDefinition = runMealy machine (runKatipContextT (busLogEnv bus) () ns . channelHassEval bus)
@@ -83,7 +84,7 @@ runController rootDir bus (Controller _enabled name machine ) = liftIO $ do
     go path inbound f = do
       msg <- atomically (readTChan inbound)
       uuid <- UUID.V4.nextRandom
-      (_, next) <- step path uuid f msg
+      (_, next) <- step path name uuid f msg
       go path inbound next
 
 lookupPort :: IO Int
@@ -102,22 +103,23 @@ defaultMain = withSocketsDo $ do
   System.Metrics.registerGcMetrics store
   appMetrics <- HomeAssistant.Runtime.Metrics.registerAppMetrics store
   rateLimitMetrics <- registerRateLimitMetrics store
-  withBus severity appMetrics $ \bus -> do
+  rootPath <- fromMaybe "/tmp/" <$> lookupEnv "HA_LIB_DIR"
+  let allNames = map (\(Controller n _) -> n) controllers
+  flags <- loadFlags rootPath allNames
+  withBus severity appMetrics flags $ \bus -> do
     token <- getEnv "HA_TOKEN"
     host <- getEnv "HA_HOST"
-    rootPath <- fromMaybe "/tmp/" <$> lookupEnv "HA_LIB_DIR"
-    rrdPath <- fromMaybe "hass-controller.rrd" <$> lookupEnv "HA_RRD_PATH"
+    let rrdPath = rootPath </> "hass-controller.rrd"
     rrdtool <- fromMaybe "rrdtool" <$> lookupEnv "HA_RRDTOOL"
     metricsPort <- lookupPort
     writerLimiter <- slidingWindowLimiter rateLimitMetrics 10 20
-    let active = [c | c@(Controller True _ _) <- controllers]
-        ents = foldMap (\(Controller _ _ m) -> entities m) active
+    let ents = foldMap (\(Controller _ m) -> entities m) controllers
         workers =
           [ ("reader", readerAction host 8123 token ents bus)
           , ("writer", writerAction writerLimiter bus)
           , ("metrics", HomeAssistant.Runtime.Metrics.metricsAction store rrdPath rrdtool)
-          , ("metrics-http", HttpServer.runHttpServer (busLogEnv bus) rrdPath rrdtool metricsPort)
-          ] ++ [ (name, runController rootPath bus c) | c@(Controller True name _) <- active ]
+          , ("metrics-http", HttpServer.runHttpServer (busLogEnv bus) rrdPath rrdtool (busFlags bus) metricsPort)
+          ] ++ [ (name, runController rootPath bus c) | c@(Controller name _) <- controllers ]
     runKatipContextT (busLogEnv bus) () mempty $
       mapConcurrently_ (uncurry supervised) workers
 

src/HomeAssistant/Runtime/Bus.hs

@@ -31,7 +31,9 @@ import System.IO (stdout)
 import System.Metrics.Counter (inc)
 import Data.UUID (toText)
 import AFRP (Request(..), Event(..))
+import Control.Monad (when)
 import Control.Monad.IO.Class (MonadIO, liftIO)
+import HomeAssistant.Runtime.Flags (Flags, isEnabled)
 
 -- | Shared runtime state: inbound is a broadcast channel (controllers
 -- read from 'dupTChan' copies), outbound queues service calls for the
@@ -43,10 +45,11 @@ data Bus = Bus
   , busGen      :: CallIdGen
   , busLogEnv   :: LogEnv
   , busMetrics  :: AppMetrics
+  , busFlags    :: Flags
   }
 
-withBus :: Severity -> AppMetrics -> (Bus -> IO a) -> IO a
-withBus severity metrics callback = do
+withBus :: Severity -> AppMetrics -> Flags -> (Bus -> IO a) -> IO a
+withBus severity metrics flags callback = do
   handleScribe <- mkHandleScribe ColorIfTerminal stdout (permitItem severity) V2
   let makeLogEnv = registerScribe "stdout" handleScribe defaultScribeSettings =<< initLogEnv "hass-controller" "production"
   -- closeScribes will stop accepting new logs, flush existing ones and clean up resources
@@ -58,6 +61,7 @@ withBus severity metrics callback = do
           <*> mkCallIdGen 0
           <*> pure le
           <*> pure metrics
+          <*> pure flags
     callback bus
 
 recordInbound :: Bus -> IO ()
@@ -70,7 +74,8 @@ channelHassEval :: (MonadIO m, KatipContext m) => Bus -> HASSEff a -> m a
 channelHassEval bus = \case
   CallService req svc -> katipAddContext (sl "traceId" (toText (requestTraceId req))) $ do
     logFM DebugS (ls $ show svc)
-    liftIO $ atomically $ writeTChan (busOutbound bus) (req, svc)
+    enabled <- isEnabled (busFlags bus) (requestHandler req)
+    when enabled $ liftIO $ atomically $ writeTChan (busOutbound bus) (req, svc)
   Debug x -> logFM DebugS (ls $ show x)
   Trace req x -> katipAddContext (sl "traceId" (toText (requestTraceId req))) $
     logFM InfoS (ls $ show x)

src/HomeAssistant/Runtime/Flags.hs

@@ -0,0 +1,90 @@
+{-# LANGUAGE OverloadedStrings #-}
+
+module HomeAssistant.Runtime.Flags
+  ( Name
+  , Flags(..)
+  , loadFlags
+  , isEnabled
+  , setEnabled
+  , allFlags
+  , validNames
+  ) where
+
+import Control.Concurrent.MVar (MVar, newMVar, withMVar)
+import Control.Concurrent.STM (TVar, atomically, newTVarIO, readTVarIO, stateTVar)
+import Control.Exception (IOException, handle)
+import Control.Monad.IO.Class (MonadIO, liftIO)
+import qualified Conduit as C
+import Conduit ((.|))
+import Data.Aeson (decodeFileStrict', encode)
+import qualified Data.ByteString.Lazy as BL
+import Data.Map.Strict (Map)
+import qualified Data.Map.Strict as M
+import Data.Set (Set)
+import qualified Data.Set as S
+import Data.Text (Text)
+import System.FilePath ((</>))
+import System.IO (hPutStrLn, stderr)
+import System.IO.Error (isDoesNotExistError)
+
+type Name = Text
+
+data Flags = Flags
+  { flagsState     :: TVar (Map Name Bool)
+  , flagsLock      :: MVar ()
+  , flagsPath      :: FilePath
+  , flagsValidNames :: Set Text
+  }
+
+loadFlags :: MonadIO m => FilePath -> [Name] -> m Flags
+loadFlags rootPath allNames = liftIO $ do
+  let path = rootPath </> "handlers.json"
+  fileMap <- readFlagsFile path
+  let defaults = M.fromList [(n, True) | n <- allNames]
+      initial = M.unionWith (\fileVal _default -> fileVal) fileMap defaults
+  tv <- newTVarIO initial
+  lock <- newMVar ()
+  pure Flags
+    { flagsState = tv
+    , flagsLock = lock
+    , flagsPath = path
+    , flagsValidNames = S.fromList allNames
+    }
+
+readFlagsFile :: FilePath -> IO (Map Name Bool)
+readFlagsFile path =
+  handle onMissingOrUnreadable $ do
+    decoded <- decodeFileStrict' path
+    case decoded of
+      Nothing -> do
+        hPutStrLn stderr ("handlers.json is unparseable; treating all handlers as enabled: " <> path)
+        pure mempty
+      Just m -> pure (maybe mempty id m)
+  where
+    onMissingOrUnreadable :: IOException -> IO (Map Name Bool)
+    onMissingOrUnreadable e
+      | isDoesNotExistError e = pure mempty
+      | otherwise = do
+          hPutStrLn stderr ("could not read handlers.json (" <> show e <> "); treating all handlers as enabled")
+          pure mempty
+
+isEnabled :: MonadIO m => Flags -> Name -> m Bool
+isEnabled flags name = liftIO $
+  M.findWithDefault True name <$> readTVarIO (flagsState flags)
+
+allFlags :: MonadIO m => Flags -> m (Map Name Bool)
+allFlags flags = liftIO $ readTVarIO (flagsState flags)
+
+setEnabled :: MonadIO m => Flags -> Name -> Bool -> m ()
+setEnabled Flags{flagsState, flagsLock, flagsPath} name val =
+  liftIO $ withMVar flagsLock $ \_ -> do
+    m <- atomically $ stateTVar flagsState $ \cur ->
+      let next = M.insert name val cur in (next, next)
+    safeWrite flagsPath m
+
+validNames :: Flags -> Set Text
+validNames = flagsValidNames
+
+safeWrite :: FilePath -> Map Name Bool -> IO ()
+safeWrite path m = C.runResourceT $ C.runConduit $
+  C.yieldMany [BL.toStrict (encode m)] .| C.sinkFileCautious path

src/HttpServer.hs

@@ -7,13 +7,17 @@ import Control.Monad.IO.Class (liftIO, MonadIO)
 import qualified Data.ByteString as BS
 import Data.Void (Void)
 import Network.Wai.Handler.Warp (run)
-import Servant.API ((:>), Capture, Get, QueryParam, (:-), MimeRender (..), Accept (..), NamedRoutes)
+import Servant.API ((:>), Capture, Get, QueryParam, (:-), MimeRender (..), Accept (..), NamedRoutes, JSON, ReqBody, Put)
 import Data.ByteString (ByteString)
 import GHC.Generics (Generic)
 import Servant (Handler, err404)
-import Control.Monad.Catch (throwM, MonadCatch, MonadThrow)
+import Control.Monad.Catch (throwM, catch, MonadCatch, MonadThrow, SomeException)
 import Servant.Server (err500, ServerT)
 import Data.Maybe (fromMaybe)
+import Data.Map.Strict (Map)
+import qualified Data.Set as S
+import Data.Text (Text)
+import HomeAssistant.Runtime.Flags (Flags, allFlags, setEnabled, validNames)
 import Control.Exception.Annotated (checkpoint, Annotation (Annotation))
 import Servant.Server.Generic (genericServeT)
 import Network.Wai (Application)
@@ -30,12 +34,27 @@ instance Accept ImagePng where
   contentType _ = "image" // "png"
 
 
-newtype API mode = API
+data API mode = API
   { getMetrics :: mode :- "metrics" :> Capture "graph" Graph :> QueryParam "range" Range :> Get '[ImagePng] ByteString
+  , getFlags   :: mode :- "flags" :> Get '[JSON] (Map Text Bool)
+  , putFlag    :: mode :- "flags" :> Capture "name" Text :> ReqBody '[JSON] Bool :> Put '[JSON] (Map Text Bool)
   }
   deriving Generic
 
 
+getFlagsHandler :: Flags -> LoggingHandler (Map Text Bool)
+getFlagsHandler flags = allFlags flags
+
+putFlagHandler :: Flags -> Text -> Bool -> LoggingHandler (Map Text Bool)
+putFlagHandler flags name val
+  | name `S.notMember` validNames flags = throwM err404
+  | otherwise = do
+      setEnabled flags name val `catch` \e -> do
+        logFM ErrorS (ls ("failed to persist handler flag: " <> show (e :: SomeException)))
+        throwM err500
+      allFlags flags
+
+
 getMetricsHandler :: FilePath -> FilePath -> Graph -> Maybe Range -> LoggingHandler ByteString
 getMetricsHandler rrdPath rrdtool graphMode mRange = checkpoint (Annotation (graphMode, mRange)) $ do
   case lookupGraph graphs graphMode of
@@ -46,14 +65,18 @@ getMetricsHandler rrdPath rrdtool graphMode mRange = checkpoint (Annotation (gra
       either (\e -> logFM ErrorS (ls e) >> throwM err500) pure g
 
 -- server :: FilePath -> FilePath -> API AsServer
-server :: FilePath -> FilePath -> ServerT (NamedRoutes API) LoggingHandler
-server rrdPath rrdtool = API { getMetrics = getMetricsHandler rrdPath rrdtool }
+server :: FilePath -> FilePath -> Flags -> ServerT (NamedRoutes API) LoggingHandler
+server rrdPath rrdtool flags = API
+  { getMetrics = getMetricsHandler rrdPath rrdtool
+  , getFlags   = getFlagsHandler flags
+  , putFlag    = putFlagHandler flags
+  }
 
-servantApp :: LogEnv -> FilePath -> FilePath -> Application
-servantApp le rrdPath rrdtool = genericServeT (toHandler le) (server rrdPath rrdtool)
+servantApp :: LogEnv -> FilePath -> FilePath -> Flags -> Application
+servantApp le rrdPath rrdtool flags = genericServeT (toHandler le) (server rrdPath rrdtool flags)
 
-runHttpServer :: MonadIO m => LogEnv -> FilePath -> FilePath -> Int -> m Void
-runHttpServer le rrdPath rrdtool port = liftIO $ forever $ run port (servantApp le rrdPath rrdtool)
+runHttpServer :: MonadIO m => LogEnv -> FilePath -> FilePath -> Flags -> Int -> m Void
+runHttpServer le rrdPath rrdtool flags port = liftIO $ forever $ run port (servantApp le rrdPath rrdtool flags)
 
 newtype LoggingHandler a = LoggingHandler (KatipContextT Handler a)
   deriving (Functor, Applicative, Monad, MonadIO, Katip, KatipContext, MonadCatch, MonadThrow) via (KatipContextT Handler)

test/AFRPSpec.hs

@@ -21,7 +21,7 @@ import Test.Hspec
 import Test.Hspec.Hedgehog
 
 fakeRequest :: Request
-fakeRequest = Request (sec 0) utc nil
+fakeRequest = Request (sec 0) utc nil "test"
 
 sec :: Integer -> UTCTime
 sec n = UTCTime (toEnum 0) (fromIntegral n)
@@ -42,7 +42,7 @@ runTimed m = go (runMealy m id)
   where
     go _ [] = []
     go w ((s, a) : as) =
-      case runIdentity (stepAuto w (Request (sec s) utc nil) a) of
+      case runIdentity (stepAuto w (Request (sec s) utc nil "test") a) of
         (b, w') -> b : go w' as
 
 -- | A minimal State monad for observing effectful arrows (e.g. whenA gating).

test/BusSpec.hs

@@ -6,6 +6,7 @@ import AFRP (Request (..), Event (..))
 import Control.Concurrent.STM
   ( atomically
   , dupTChan
+  , isEmptyTChan
   , readTChan
   , writeTChan
   )
@@ -15,9 +16,11 @@ import Data.Time (UTCTime (..), utc)
 import Data.UUID (nil)
 import HomeAssistant.Controller (HASSEff (..), Service (..), Target(..))
 import HomeAssistant.Runtime.Bus
+import HomeAssistant.Runtime.Flags (loadFlags, setEnabled)
 import HomeAssistant.Runtime.Metrics (registerAppMetrics)
 import Katip (Namespace (Namespace), runKatipContextT, Severity (..))
 import qualified System.Metrics as Metrics
+import System.IO.Temp (withTempDirectory)
 import Test.Hspec
 
 spec :: Spec
@@ -33,13 +36,22 @@ spec = describe "Bus" $ do
     r2 `shouldBe` (Event (Number 1), Event (Number 2))
 
   it "channelHassEval writes CallService to the outbound channel" $ withTestBus $ \bus -> do
-    let req = Request (UTCTime (toEnum 0) 0) utc nil
+    let req = Request (UTCTime (toEnum 0) 0) utc nil "test"
         svc = Service "light" "turn_on" Nothing [EntityId "light.bedroom_masse"]
     runKatipContextT (busLogEnv bus) () (Namespace ["test"]) $
       channelHassEval bus (CallService req svc)
     (_, svc') <- atomically $ readTChan (busOutbound bus)
     svc' `shouldBe` svc
 
+  it "channelHassEval drops CallService when the handler is disabled" $
+    withTestFlagsBus $ \bus -> do
+      setEnabled (busFlags bus) "test-handler" False
+      let req = Request (UTCTime (toEnum 0) 0) utc nil "test-handler"
+          svc = Service "light" "turn_on" Nothing [EntityId "light.test"]
+      runKatipContextT (busLogEnv bus) () (Namespace ["test"]) $
+        channelHassEval bus (CallService req svc)
+      atomically (isEmptyTChan (busOutbound bus)) `shouldReturn` True
+
 
   it "generates unique sequential call ids" $ do
     gen <- mkCallIdGen 0
@@ -51,7 +63,9 @@ spec = describe "Bus" $ do
     it "increments the trigger and service counters" $ do
       store <- Metrics.newStore
       m <- registerAppMetrics store
-      withBus InfoS m $ \bus -> do
+      withTempDirectory "/tmp" "bus-spec" $ \dir -> do
+        flags <- loadFlags dir []
+        withBus InfoS m flags $ \bus -> do
           recordInbound bus
           recordInbound bus
           recordOutbound bus
@@ -63,4 +77,14 @@ withTestBus :: (Bus -> IO a) -> IO a
 withTestBus action = do
   store <- Metrics.newStore
   m <- registerAppMetrics store
-  withBus InfoS m action
+  withTempDirectory "/tmp" "bus-spec" $ \dir -> do
+    flags <- loadFlags dir []
+    withBus InfoS m flags action
+
+withTestFlagsBus :: (Bus -> IO a) -> IO a
+withTestFlagsBus action = do
+  store <- Metrics.newStore
+  m <- registerAppMetrics store
+  withTempDirectory "/tmp" "bus-spec" $ \dir -> do
+    flags <- loadFlags dir ["test-handler"]
+    withBus InfoS m flags action

test/ConnectionSpec.hs

@@ -47,7 +47,7 @@ spec = do
 
 req :: Int -> Request
 req n = Request (UTCTime (toEnum 0) (fromIntegral (0 :: Int))) utc
-          (fromJust (fromString uuid))
+          (fromJust (fromString uuid)) "test"
   where
     pad i = replicate (12 - length (show i)) '0' <> show i
     uuid = "00000000-0000-0000-0000-" <> pad n

test/FlagsSpec.hs

@@ -0,0 +1,75 @@
+{-# LANGUAGE OverloadedStrings #-}
+
+module FlagsSpec (spec) where
+
+import Control.Concurrent.Async (mapConcurrently_)
+import Control.Monad.IO.Class (liftIO)
+import Data.Aeson (decodeFileStrict)
+import Data.Map.Strict (Map)
+import qualified Data.Map.Strict as M
+import Data.Text (Text)
+import qualified Hedgehog.Gen as Gen
+import qualified Hedgehog.Range as Range
+import System.IO.Temp (withTempDirectory)
+import Test.Hspec
+import Test.Hspec.Hedgehog
+
+import HomeAssistant.Runtime.Flags
+
+spec :: Spec
+spec = describe "Flags" $ do
+  describe "loadFlags" $ do
+    it "defaults all names to True when the file is missing (opt-out)" $
+      withTempDirectory "/tmp" "flags-spec" $ \dir -> do
+        flags <- loadFlags dir ["a", "b"]
+        m <- allFlags flags
+        m `shouldBe` M.fromList [("a" :: Text, True), ("b", True)]
+
+    it "lets the file override the True default, missing keys stay True" $
+      withTempDirectory "/tmp" "flags-spec" $ \dir -> do
+        let path = dir <> "/handlers.json"
+        writeFile path "{\"b\": false}"
+        flags <- loadFlags dir ["a", "b"]
+        m <- allFlags flags
+        m `shouldBe` M.fromList [("a" :: Text, True), ("b" :: Text, False)]
+
+    it "treats a corrupt file as empty (all-enabled) without throwing" $
+      withTempDirectory "/tmp" "flags-spec" $ \dir -> do
+        let path = dir <> "/handlers.json"
+        writeFile path "not json at all"
+        flags <- loadFlags dir ["a"]
+        m <- allFlags flags
+        m `shouldBe` M.fromList [("a" :: Text, True)]
+
+  describe "isEnabled" $ do
+    it "returns the stored value" $
+      withTempDirectory "/tmp" "flags-spec" $ \dir -> do
+        let path = dir <> "/handlers.json"
+        writeFile path "{\"a\": false}"
+        flags <- loadFlags dir ["a"]
+        isEnabled flags "a" `shouldReturn` False
+
+    it "defaults unknown names to True" $
+      withTempDirectory "/tmp" "flags-spec" $ \dir -> do
+        flags <- loadFlags dir []
+        isEnabled flags "unknown" `shouldReturn` True
+
+  describe "setEnabled" $ do
+    it "updates the in-memory map and persists to disk" $
+      withTempDirectory "/tmp" "flags-spec" $ \dir -> do
+        flags <- loadFlags dir ["a"]
+        setEnabled flags "a" False
+        isEnabled flags "a" `shouldReturn` False
+        -- reload from disk to confirm persistence
+        flags' <- loadFlags dir ["a"]
+        isEnabled flags' "a" `shouldReturn` False
+
+    it "concurrent writes leave the file consistent with the TVar" $
+      hedgehog $ do
+        n <- forAll $ Gen.int (Range.linear 1 50)
+        liftIO $ withTempDirectory "/tmp" "flags-spec" $ \dir -> do
+          flags <- loadFlags dir ["x"]
+          mapConcurrently_ (\i -> setEnabled flags "x" (even i)) [1 .. n]
+          m <- allFlags flags
+          decoded <- decodeFileStrict (dir <> "/handlers.json")
+          (decoded :: Maybe (Map Text Bool)) `shouldBe` Just m

test/Main.hs

@@ -6,6 +6,7 @@ import qualified AFRPSpec
 import qualified BedroomSpec
 import qualified BusSpec
 import qualified ConnectionSpec
+import qualified FlagsSpec
 import qualified GraphingSpec
 import qualified MetricsSpec
 import qualified RuntimeSpec
@@ -17,6 +18,7 @@ main = hspec $ do
   BedroomSpec.spec
   BusSpec.spec
   ConnectionSpec.spec
+  FlagsSpec.spec
   GraphingSpec.spec
   MetricsSpec.spec
   RuntimeSpec.spec

test/Support.hs

@@ -20,7 +20,7 @@ import AFRP (Mealy (..), Request (..), stepAuto)
 import HomeAssistant.Controller (HASSEff (..), Service)
 
 fakeRequest :: Request
-fakeRequest = Request (sec 0) utc nil
+fakeRequest = Request (sec 0) utc nil "test"
 
 sec :: Integer -> UTCTime
 sec n = UTCTime (toEnum 0) (fromIntegral n)