Provide command-line flag for db pool size

src/Dbapi.hs

@@ -49,6 +49,7 @@ data AppConfig = AppConfig {
   , configPort  :: Int
   , configAnonRole :: String
   , configSecure :: Bool
+  , configPool :: Int
   }
 
 data AuthUser = AuthUser {

src/Main.hs

@@ -26,12 +26,14 @@ argParser = AppConfig
   <*> strOption (long "anonymous" <> short 'a' <> metavar "ROLE"
     <> help "postgres role to use for non-authenticated requests")
   <*> switch (long "secure" <> short 's'
-    <> help "Redirect all requests to HTTPS" )
+    <> help "Redirect all requests to HTTPS")
+  <*> option (long "db-pool" <> metavar "NUMBER" <> value 10
+    <> help "Max connections in database pool")
 
 main :: IO ()
 main = do
   conf <- execParser (info (helper <*> argParser) describe)
-  pool <- createPool (connectPostgreSQL' (configDbUri conf)) disconnect 1 600 10
+  pool <- createPool (connectPostgreSQL' (configDbUri conf)) disconnect 1 600 (configPool conf)
   let port = configPort conf
 
   unless (configSecure conf) $