Adds configuration from env variables

bower.json

@@ -9,16 +9,15 @@
   "dependencies": {
     "purescript-prelude": "^3.1.0",
     "purescript-console": "^3.0.0",
-    "purescript-foreign-generic": "^5.0.0",
+    "purescript-foreign-generic": "^4.1.0",
     "purescript-postgresql-client": "^2.1.0",
     "purescript-aff": "^3.1.0",
     "purescript-express": "^0.5.2",
-    "purescript-integers": "^3.1.0"
+    "purescript-integers": "^3.1.0",
+    "purescript-node-process": "^4.0.0",
+    "purescript-config": "^0.0.6"
   },
   "devDependencies": {
     "purescript-psci-support": "^3.0.0"
-  },
-  "resolutions": {
-    "purescript-foreign-generic": "^4.1.0"
   }
 }

setenv.sh

@@ -0,0 +1,8 @@
+export SS_PORT=4000
+export SS_DB_USER="abhinav"
+export SS_DB_PASSWORD=""
+export SS_DB_HOST="localhost"
+export SS_DB_PORT=5432
+export SS_DB_DATABASE="simple_server"
+export SS_DB_POOL_SIZE=10
+export SS_DB_IDLE_CONN_TIMEOUT_MILLIS=1000

src/Main.purs

@@ -3,23 +3,24 @@ module Main where
 import Prelude
 
 import Control.Monad.Eff (Eff)
-import Control.Monad.Eff.Console (CONSOLE)
+import Control.Monad.Eff.Console (CONSOLE, log)
+import Data.Either (Either(..))
+import Data.Set (toUnfoldable)
+import Data.String (joinWith)
 import Database.PostgreSQL as PG
 import Node.Express.Types (EXPRESS)
+import Node.Process (PROCESS)
+import Node.Process as Process
+import SimpleService.Config (readServerConfig)
 import SimpleService.Server (runServer)
 
 main :: forall eff. Eff ( console :: CONSOLE
                         , express :: EXPRESS
                         , postgreSQL :: PG.POSTGRESQL
+                        , process :: PROCESS
                         | eff) Unit
-main = runServer port databaseConfig
-  where
-    port = 4000
-    databaseConfig = { user: "abhinav"
-                     , password: ""
-                     , host: "localhost"
-                     , port: 5432
-                     , database: "simple_service"
-                     , max: 10
-                     , idleTimeoutMillis: 1000
-                     }
+main = readServerConfig >>= case _ of
+  Left missingKeys -> do
+    log $ "Unable to start. Missing Env keys: " <> joinWith ", " (toUnfoldable missingKeys)
+    Process.exit 1
+  Right { port, databaseConfig } -> runServer port databaseConfig

src/SimpleService/Config.purs

@@ -0,0 +1,40 @@
+module SimpleService.Config where
+
+import Data.Config
+import Prelude
+
+import Control.Monad.Eff (Eff)
+import Data.Config.Node (fromEnv)
+import Data.Either (Either)
+import Data.Set (Set)
+import Database.PostgreSQL as PG
+import Node.Process (PROCESS)
+
+type ServerConfig =
+  { port           :: Int
+  , databaseConfig :: PG.PoolConfiguration
+  }
+
+databaseConfig :: Config {name :: String} PG.PoolConfiguration
+databaseConfig =
+  { user: _, password: _, host: _, port: _, database: _, max: _, idleTimeoutMillis: _ }
+  <$> string {name: "user"}
+  <*> string {name: "password"}
+  <*> string {name: "host"}
+  <*> int    {name: "port"}
+  <*> string {name: "database"}
+  <*> int    {name: "pool_size"}
+  <*> int    {name: "idle_conn_timeout_millis"}
+
+portConfig :: Config {name :: String} Int
+portConfig = int {name: "port"}
+
+serverConfig :: Config {name :: String} ServerConfig
+serverConfig =
+  { port: _, databaseConfig: _}
+  <$> portConfig
+  <*> prefix {name: "db"} databaseConfig
+
+readServerConfig :: forall eff.
+                    Eff (process :: PROCESS | eff) (Either (Set String) ServerConfig)
+readServerConfig = fromEnv "SS" serverConfig