Allow server hostname via ENV

config/releases.exs

@@ -33,9 +33,16 @@ zcashd_password =
     environment variable ZCASHD_PASSWORD is missing 
     """
 
+explorer_hostname =
+  System.fetch_env!("EXPLORER_HOSTNAME") ||
+    raise """
+    environment variable EXPLORER_HOSTNAME is missing 
+    """
+
 config :zcash_explorer, ZcashExplorerWeb.Endpoint,
   http: [
     port: String.to_integer(System.get_env("PORT") || "4000"),
+    host: explorer_hostname,
     transport_options: [socket_opts: [:inet6]]
   ],
   secret_key_base: secret_key_base