Set last will (#56)

* add last will and comment disconnect

* contribution

* put back manual server offline

CONTRIBUTING.md

@@ -20,3 +20,10 @@ go install
 go run .
 ```
 
+### Build for docker
+
+```shell
+CGO_ENABLED=0 GOOS=linux GOARCH=amd64
+docker compose build
+```
+

Makefile

@@ -3,12 +3,12 @@ PLATFORM=local
 
 # Build all files.
 build:
-	@echo "==> Building ./dist/sdm"
+	@echo "==> Building..."
 	env GOOS=linux GOARCH=amd64 go build -o dist/digitalstrom-mqtt-amd64 ./main.go
 .PHONY: build
 
 build-arm:
-	@echo "==> Building ./dist/sdm"
+	@echo "==> Building..."
 	env GOOS=linux GOARCH=arm GOARM=5 go build -o dist/digitalstrom-mqtt-arm ./main.go
 .PHONY: build
 

pkg/mqtt/client.go

@@ -68,11 +68,12 @@ func NewClient(options *ClientOptions) Client {
 	}
 	mqttOptions := mqtt.NewClientOptions().
 		AddBroker(options.MqttUrl).
-		SetClientID("digitalstrom-mqtt-" + uuid.New().String()).
+		SetClientID("digitalstrom-mqtt-"+uuid.New().String()).
 		SetOrderMatters(false).
 		SetUsername(options.Username).
 		SetPassword(options.Password).
 		SetAutoReconnect(true).
+		SetWill(serverStatus, Offline, QOS, true).
 		SetReconnectingHandler(func(client mqtt.Client, opts *mqtt.ClientOptions) {
 			log.Info().Str("url", options.MqttUrl).Msg("Reconnecting to MQTT server.")
 			subscriptions.shouldReconnect = true