[Holmusk#59] Introduce TOML config (Holmusk#65)

* [Holmusk#59] Introduce TOML config

Resolves Holmusk#59

* Fix Stack build

Author: vrom911

config.toml

@@ -0,0 +1,2 @@
+dbCredentials = "host=localhost port=5432 user=root dbname=three-layer"
+log.severity  = "Debug"

src/Lib.hs

@@ -9,6 +9,7 @@ import Servant.Server (serve)
 import System.Remote.Monitoring (forkServerWith)
 
 import Lib.App (AppEnv, Env (..))
+import Lib.Config (Config (..), loadConfig)
 import Lib.Core.Jwt (JwtSecret (..), mkRandomString)
 import Lib.Db (initialisePool)
 import Lib.Effects.Log (mainLogAction)
@@ -17,10 +18,10 @@ import Lib.Server (API, server)
 import qualified Data.HashMap.Strict as HashMap
 import qualified System.Metrics as Metrics
 
-mkAppEnv :: IO AppEnv
-mkAppEnv = do
+mkAppEnv :: Config -> IO AppEnv
+mkAppEnv Config{..} = do
     -- IO configuration
-    envDbPool   <- initialisePool
+    envDbPool   <- initialisePool cDbCredentials
     envSessions <- newMVar HashMap.empty
     envTimings  <- newIORef HashMap.empty
     envEkgStore <- Metrics.newStore
@@ -29,7 +30,7 @@ mkAppEnv = do
 
     -- pure configuration
     let envSessionExpiry = 600
-    let envLogAction = mainLogAction D
+    let envLogAction = mainLogAction cLogSeverity
     pure Env{..}
 
 runServer :: AppEnv -> IO ()
@@ -42,4 +43,4 @@ runServer env@Env{..} = do
     application = serve (Proxy @API) (server env)
 
 main :: IO ()
-main = mkAppEnv >>= runServer
+main = loadConfig >>= mkAppEnv >>= runServer

src/Lib/Config.hs

@@ -0,0 +1,28 @@
+{- | Configurations through the @config.toml@ file@.
+-}
+
+module Lib.Config
+       ( Config (..)
+       , loadConfig
+       ) where
+
+import Toml (TomlCodec, (.=))
+
+import qualified Toml
+
+
+-- | Data type for the configurable elements of the application.
+data Config = Config
+    { cDbCredentials :: !ByteString
+    , cLogSeverity   :: !Severity
+    }
+
+-- | TOML codec for the 'Config' data type.
+configT :: TomlCodec Config
+configT = Config
+    <$> Toml.byteString "dbCredentials" .= cDbCredentials
+    <*> Toml.read       "log.severity"  .= cLogSeverity
+
+-- | Loads the @config.toml@ file.
+loadConfig :: MonadIO m => m Config
+loadConfig = Toml.decodeFile configT "config.toml"

src/Lib/Db/Functions.hs

@@ -28,12 +28,8 @@ import qualified Database.PostgreSQL.Simple as Sql
 type WithDb env m = (MonadReader env m, Has DbPool env, MonadIO m)
 
 -- | Create 'Pool.Pool' by given credentials.
-initialisePool :: IO DbPool
-initialisePool = Pool.createPool (Sql.connectPostgreSQL credentials) Sql.close 10 5 10
-  where
-    -- TODO: put into TOML config
-    credentials :: ByteString
-    credentials = "host=localhost port=5432 user=root dbname=three-layer"
+initialisePool :: ByteString -> IO DbPool
+initialisePool credentials = Pool.createPool (Sql.connectPostgreSQL credentials) Sql.close 10 5 10
 
 -- | Performs a query without arguments and returns the resulting rows.
 queryRaw

stack.yaml

@@ -15,4 +15,5 @@ extra-deps:
   - servant-0.16.0.1
   - servant-server-0.16
   - servant-proto-lens-0.1.0.3
+  - tomland-1.0.0
   - typerep-map-0.3.2

test/Spec.hs

@@ -8,6 +8,7 @@ import Test.Hspec.Core.Spec (sequential)
 
 import Lib (mkAppEnv)
 import Lib.App (AppEnv, Env (..))
+import Lib.Config (loadConfig)
 import Lib.Db (prepareDb)
 import Lib.Effects.Log (runAppLogIO_)
 
@@ -35,7 +36,7 @@ hedgehogTests = Group "Roundtrip properties"
 
 main :: IO ()
 main = bracket
-    mkAppEnv
+    (loadConfig >>= mkAppEnv)
     (\Env{..} -> Pool.destroyAllResources envDbPool)
     runTests
   where

three-layer.cabal

@@ -72,6 +72,8 @@ library
                            Lib.App.Error
                            Lib.App.Monad
 
+                         Lib.Config
+
                          -- core modules
                          Lib.Core.Admin
                          Lib.Core.Email
@@ -133,6 +135,7 @@ library
                      , servant-server ^>= 0.16
                      , text
                      , time >= 1.8 && < 1.10
+                     , tomland ^>= 1.0.0
                      , unordered-containers
                      , warp ^>= 3.2