Method derpMapUpdates

coderd/workspaceagents.go:1225–1294

@Summary Get DERP map updates @ID get-derp-map-updates @Security CoderSessionToken @Tags Agents @Success 101 @Router /api/v2/derp-map [get]

(rw http.ResponseWriter, r *http.Request)

// @Success 101
// @Router /api/v2/derp-map [get]
func (api *API) derpMapUpdates(rw http.ResponseWriter, r *http.Request) {
	ctx := r.Context()

	api.WebsocketWaitMutex.Lock()
	api.WebsocketWaitGroup.Add(1)
	api.WebsocketWaitMutex.Unlock()
	defer api.WebsocketWaitGroup.Done()

	ws, err := websocket.Accept(rw, r, nil)
	if err != nil {
		httpapi.Write(ctx, rw, http.StatusBadRequest, codersdk.Response{
			Message: "Failed to accept websocket.",
			Detail:  err.Error(),
		})
		return
	}
	encoder := wsjson.NewEncoder[*tailcfg.DERPMap](ws, websocket.MessageBinary)
	defer encoder.Close(websocket.StatusGoingAway)

	// Log the request immediately instead of after it completes.
	if rl := loggermw.RequestLoggerFromContext(ctx); rl != nil {
		rl.WriteLog(ctx, http.StatusAccepted)
	}

	go func(ctx context.Context) {
		// TODO(mafredri): Is this too frequent? Use separate ping disconnect timeout?
		t := time.NewTicker(api.AgentConnectionUpdateFrequency)
		defer t.Stop()

		for {
			select {
			case <-t.C:
			case <-ctx.Done():
				return
			}

			ctx, cancel := context.WithTimeout(ctx, 30*time.Second)
			err := ws.Ping(ctx)
			cancel()
			if err != nil {
				_ = ws.Close(websocket.StatusGoingAway, "ping failed")
				return
			}
		}
	}(ctx)

	ticker := time.NewTicker(api.Options.DERPMapUpdateFrequency)
	defer ticker.Stop()

	var lastDERPMap *tailcfg.DERPMap
	for {
		derpMap := api.DERPMap()
		if lastDERPMap == nil || !tailnet.CompareDERPMaps(lastDERPMap, derpMap) {
			err := encoder.Encode(derpMap)
			if err != nil {
				return
			}
			lastDERPMap = derpMap