Add proxy awareness for OpenAPI spec generation

Proxy uri from command line options takes precedence over host and port

src/PostgREST/Config.hs

@@ -38,6 +38,7 @@ import           Web.JWT                     (Secret, secret)
 data AppConfig = AppConfig {
     configDatabase  :: String
   , configAnonRole  :: String
+  , configProxyUri  :: Maybe String
   , configSchema    :: String
   , configHost      :: String
   , configPort      :: Int
@@ -51,6 +52,7 @@ argParser :: Parser AppConfig
 argParser = AppConfig
   <$> argument str (help "(REQUIRED) database connection string, e.g. postgres://user:pass@host:port/db" <> metavar "DB_URL")
   <*> strOption    (long "anonymous"  <> short 'a' <> help "(REQUIRED) postgres role to use for non-authenticated requests" <> metavar "ROLE")
+  <*> (optional . strOption) (long "proxy-uri"  <> short 'x' <> help "proxy uri of the HTTP server" <> metavar "PROXY")
   <*> strOption    (long "schema"     <> short 's' <> help "schema to use for API routes" <> metavar "NAME" <> value "public" <> showDefault)
   <*> strOption    (long "host"       <> short 'l' <> help "hostname or ip on which to run HTTP server" <> metavar "HOST" <> value "*4" <> showDefault)
   <*> option auto  (long "port"       <> short 'p' <> help "port number on which to run HTTP server" <> metavar "PORT" <> value 3000 <> showDefault)