Update config to be passed in as environment variables

cmd/invertergui/config.go

@@ -0,0 +1,34 @@
+package main
+
+import (
+	"github.com/jessevdk/go-flags"
+)
+
+type config struct {
+	Address string `long:"address" env:"ADDRESS" default:":8080" description:"The IP/DNS and port of the machine that the application is running on."`
+	Data    struct {
+		Source string `long:"data.source" env:"DATA_SOURCE" default:"serial" description:"Set the source of data for the inverter gui. \"serial\", \"tcp\" or \"mock\""`
+		Host   string `long:"data.host" env:"DATA_HOST" default:"localhost:8139" description:"Host to connect when source is set to tcp."`
+		Device string `long:"data.device" env:"DATA_DEVICE" default:"/dev/ttyUSB0" description:"TTY device to use when source is set to serial."`
+	}
+	Cli struct {
+		Enabled bool `long:"cli.enabled" env:"CLI_ENABLED" description:"Enable CLI output."`
+	}
+	MQTT struct {
+		Enabled  bool   `long:"mqtt.enabled" env:"MQTT_ENABLED" description:"Enable MQTT publishing."`
+		Broker   string `long:"mqtt.broker" env:"MQTT_BROKER" default:"tcp://localhost:1883" description:"Set the host port and scheme of the MQTT broker."`
+		ClientID string `long:"mqtt.client_id" env:"MQTT_CLIENT_ID" default:"interter-gui" description:"Set the client ID for the MQTT connection."`
+		Topic    string `long:"mqtt.topic" env:"MQTT_TOPIC" default:"invertergui/updates" description:"Set the MQTT topic updates published to."`
+		Username string `long:"mqtt.username" env:"MQTT_USERNAME" default:"" description:"Set the MQTT username"`
+		Password string `long:"mqtt.password" env:"MQTT_PASSWORD" default:"" description:"Set the MQTT password"`
+	}
+}
+
+func parseConfig() (*config, error) {
+	conf := &config{}
+	parser := flags.NewParser(conf, flags.Default)
+	if _, err := parser.Parse(); err != nil {
+		return nil, err
+	}
+	return conf, nil
+}