feat: Add browser-only connections to Enterprise (#4135)

* feat: Add browser-only connections to Enterprise

Fixes #4131.

* Fix formatting

codersdk/features.go

@@ -15,12 +15,13 @@ const (
 )
 
 const (
-	FeatureUserLimit = "user_limit"
-	FeatureAuditLog  = "audit_log"
-	FeatureSCIM      = "scim"
+	FeatureUserLimit   = "user_limit"
+	FeatureAuditLog    = "audit_log"
+	FeatureBrowserOnly = "browser_only"
+	FeatureSCIM        = "scim"
 )
 
-var FeatureNames = []string{FeatureUserLimit, FeatureAuditLog, FeatureSCIM}
+var FeatureNames = []string{FeatureUserLimit, FeatureAuditLog, FeatureBrowserOnly, FeatureSCIM}
 
 type Feature struct {
 	Entitlement Entitlement `json:"entitlement"`

codersdk/workspaceagents.go

@@ -270,12 +270,14 @@ func (c *Client) DialWorkspaceAgentTailnet(ctx context.Context, logger slog.Logg
 	}
 	ctx, cancelFunc := context.WithCancel(ctx)
 	closed := make(chan struct{})
+	first := make(chan error)
 	go func() {
 		defer close(closed)
+		isFirst := true
 		for retrier := retry.New(50*time.Millisecond, 10*time.Second); retrier.Wait(ctx); {
 			logger.Debug(ctx, "connecting")
 			// nolint:bodyclose
-			ws, _, err := websocket.Dial(ctx, coordinateURL.String(), &websocket.DialOptions{
+			ws, res, err := websocket.Dial(ctx, coordinateURL.String(), &websocket.DialOptions{
 				HTTPClient: httpClient,
 				// Need to disable compression to avoid a data-race.
 				CompressionMode: websocket.CompressionDisabled,
@@ -283,10 +285,22 @@ func (c *Client) DialWorkspaceAgentTailnet(ctx context.Context, logger slog.Logg
 			if errors.Is(err, context.Canceled) {
 				return
 			}
+			if isFirst {
+				if res.StatusCode == http.StatusConflict {
+					first <- readBodyAsError(res)
+					return
+				}
+				isFirst = false
+				close(first)
+			}
 			if err != nil {
 				logger.Debug(ctx, "failed to dial", slog.Error(err))
 				continue
 			}
+			if isFirst {
+				isFirst = false
+				close(first)
+			}
 			sendNode, errChan := tailnet.ServeCoordinator(websocket.NetConn(ctx, ws, websocket.MessageBinary), func(node []*tailnet.Node) error {
 				return conn.UpdateNodes(node)
 			})
@@ -305,13 +319,19 @@ func (c *Client) DialWorkspaceAgentTailnet(ctx context.Context, logger slog.Logg
 			_ = ws.Close(websocket.StatusAbnormalClosure, "")
 		}
 	}()
+	err = <-first
+	if err != nil {
+		cancelFunc()
+		_ = conn.Close()
+		return nil, err
+	}
 	return &agent.Conn{
 		Conn: conn,
 		CloseFunc: func() {
 			cancelFunc()
 			<-closed
 		},
-	}, nil
+	}, err
 }
 
 // WorkspaceAgent returns an agent by ID.