feat: add websocket and dockerfile to build location

build/package/Dockerfile.location

@@ -0,0 +1,17 @@
+# syntax=docker/dockerfile:1
+
+FROM golang:1.24.0 AS builder
+WORKDIR /app
+
+COPY go.mod go.sum ./
+RUN go mod download
+
+COPY . .
+RUN CGO_ENABLED=0 GOOS=linux go build -a -installsuffix cgo -o location ./cmd/location
+
+FROM alpine:latest
+RUN apk add --no-cache ca-certificates
+WORKDIR /app
+COPY --from=builder /app/location .
+
+ENTRYPOINT ["./location"]

cmd/server/main.go

@@ -2,11 +2,14 @@ package main
 
 import (
 	"context"
+	"encoding/json"
 	"fmt"
+	"log"
 	"net/http"
 	"os/signal"
 	"sync"
 	"syscall"
+	"time"
 
 	"github.com/AFASystems/presence/internal/pkg/common/appcontext"
 	"github.com/AFASystems/presence/internal/pkg/config"
@@ -16,8 +19,14 @@ import (
 	"github.com/AFASystems/presence/internal/pkg/service"
 	"github.com/gorilla/handlers"
 	"github.com/gorilla/mux"
+	"github.com/gorilla/websocket"
 )
 
+var upgrader = websocket.Upgrader{
+	ReadBufferSize:  1024,
+	WriteBufferSize: 1024,
+}
+
 var wg sync.WaitGroup
 
 func main() {
@@ -51,7 +60,7 @@ func main() {
 	r := mux.NewRouter()
 
 	// For now just add beacon DELETE / GET / POST / PUT methods
-	r.HandleFunc("/api/beacons/{beacon_id}", controller.BeaconsDeleteController(writer, ctx)).Methods("DELETE")
+	r.HandleFunc("/api/beacons/{beacon_id}", controller.BeaconsDeleteController(writer, ctx, appState)).Methods("DELETE")
 	r.HandleFunc("/api/beacons", controller.BeaconsListController(appState)).Methods("GET")
 	r.HandleFunc("/api/beacons/{beacon_id}", controller.BeaconsListSingleController(appState)).Methods("GET")
 	r.HandleFunc("/api/beacons", controller.BeaconsAddController(writer, ctx)).Methods("POST")
@@ -60,6 +69,8 @@ func main() {
 	r.HandleFunc("/api/settings", controller.SettingsListController(appState, client, ctx)).Methods("GET")
 	r.HandleFunc("/api/settings", controller.SettingsEditController(settingsWriter, appState, client, ctx)).Methods("POST")
 
+	r.HandleFunc("/api/beacons/ws", serveWs(appState, ctx))
+
 	http.ListenAndServe(cfg.HTTPAddr, handlers.CORS(originsOk, headersOk, methodsOk)(r))
 
 eventLoop:
@@ -87,3 +98,67 @@ eventLoop:
 	fmt.Println("All kafka clients shutdown, starting shutdown of valkey client")
 	appState.CleanValkeyClient()
 }
+
+func serveWs(appstate *appcontext.AppState, ctx context.Context) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		ws, err := upgrader.Upgrade(w, r, nil)
+		if err != nil {
+			if _, ok := err.(websocket.HandshakeError); !ok {
+				log.Println(err)
+			}
+			return
+		}
+		wg.Add(1)
+		go writer(ws, appstate, ctx)
+		reader(ws)
+	}
+}
+
+func writer(ws *websocket.Conn, appstate *appcontext.AppState, ctx context.Context) {
+	pingTicker := time.NewTicker((60 * 9) / 10 * time.Second)
+	beaconTicker := time.NewTicker(2 * time.Second)
+	defer func() {
+		pingTicker.Stop()
+		beaconTicker.Stop()
+		ws.Close()
+		wg.Done()
+	}()
+	for {
+		select {
+		case <-ctx.Done():
+			log.Println("WebSocket writer received shutdown signal.")
+			ws.SetWriteDeadline(time.Now().Add(10 * time.Second))
+			ws.WriteMessage(websocket.CloseMessage, websocket.FormatCloseMessage(websocket.CloseNormalClosure, ""))
+			return
+		case <-beaconTicker.C:
+			beacons := appstate.GetAllBeacons()
+			js, err := json.Marshal(beacons)
+			if err != nil {
+				js = []byte("error")
+			}
+
+			ws.SetWriteDeadline(time.Now().Add(10 * time.Second))
+			if err := ws.WriteMessage(websocket.TextMessage, js); err != nil {
+				return
+			}
+		case <-pingTicker.C:
+			ws.SetWriteDeadline(time.Now().Add(10 * time.Second))
+			if err := ws.WriteMessage(websocket.PingMessage, []byte{}); err != nil {
+				return
+			}
+		}
+	}
+}
+
+func reader(ws *websocket.Conn) {
+	defer ws.Close()
+	ws.SetReadLimit(512)
+	ws.SetReadDeadline(time.Now().Add((60 * 9) / 10 * time.Second))
+	ws.SetPongHandler(func(string) error { ws.SetReadDeadline(time.Now().Add((60 * 9) / 10 * time.Second)); return nil })
+	for {
+		_, _, err := ws.ReadMessage()
+		if err != nil {
+			break
+		}
+	}
+}

internal/pkg/common/appcontext/context.go

@@ -167,6 +167,12 @@ func (m *AppState) RemoveBeaconFromLookup(id string) {
 	delete(m.beaconsLookup, id)
 }
 
+func (m *AppState) RemoveBeacon(id string) {
+	m.beacons.Lock.Lock()
+	delete(m.beacons.Beacons, id)
+	m.beacons.Lock.Unlock()
+}
+
 // BeaconExists checks if a beacon exists in the lookup
 func (m *AppState) BeaconExists(id string) bool {
 	_, exists := m.beaconsLookup[id]

internal/pkg/controller/beacons_controller.go

@@ -59,7 +59,7 @@ func sendKafkaMessage(writer *kafka.Writer, value *model.ApiUpdate, ctx context.
 	return nil
 }
 
-func BeaconsDeleteController(writer *kafka.Writer, ctx context.Context) http.HandlerFunc {
+func BeaconsDeleteController(writer *kafka.Writer, ctx context.Context, appstate *appcontext.AppState) http.HandlerFunc {
 	return func(w http.ResponseWriter, r *http.Request) {
 		vars := mux.Vars(r)
 		beaconId := vars["beacon_id"]
@@ -76,6 +76,8 @@ func BeaconsDeleteController(writer *kafka.Writer, ctx context.Context) http.Han
 			return
 		}
 
+		// If message is succesfully sent delete the beacon from the list
+		appstate.RemoveBeacon(beaconId)
 		w.Write([]byte("ok"))
 	}
 }