feat: handle port forward subdomain conflict

internal/apierror/api_error.go

@@ -5,7 +5,7 @@ import "fmt"
 type APIError struct {
 	StatusCode int    `json:"-"`
 	Code       string `json:"code"`
-	Message    string `json:"error"`
+	Message    string `json:"error,omitempty"`
 }
 
 func New(status int, code, message string) *APIError {

internal/reverseproxy/errors.go

@@ -0,0 +1,5 @@
+package reverseproxy
+
+import "errors"
+
+var ErrPortMappingConflict = errors.New("port mapping conflict")

internal/reverseproxy/proxy.go

@@ -43,9 +43,14 @@ func (p *ReverseProxy) Middleware() echo.MiddlewareFunc {
 	}
 }
 
-func (p *ReverseProxy) AddEntry(subdomain string, url *url.URL) {
+func (p *ReverseProxy) AddEntry(subdomain string, url *url.URL) error {
+	_, ok := p.httpProxies[subdomain]
+	if ok {
+		return ErrPortMappingConflict
+	}
 	proxy := httputil.NewSingleHostReverseProxy(url)
 	p.httpProxies[subdomain] = proxy
+	return nil
 }
 
 func (p *ReverseProxy) RemoveEntry(subdomain string) {

internal/workspace/errors.go

@@ -1,9 +1,19 @@
 package workspace
 
+import "strings"
+
 type errWorkspaceExists struct {
 	message string
 }
 
+type errPortMappingConflicts struct {
+	conflicts []string
+}
+
 func (err *errWorkspaceExists) Error() string {
 	return err.message
 }
+
+func (err *errPortMappingConflicts) Error() string {
+	return "Subdomain(s) already in use: " + strings.Join(err.conflicts, ", ")
+}

internal/workspace/http_handlers.go

@@ -126,6 +126,10 @@ func updateWorkspace(c echo.Context, workspace *workspace) error {
 
 	if len(body.PortMappings) > 0 {
 		if err = mgr.addPortMappings(ctx, workspace, body.PortMappings); err != nil {
+			var errPortMappingConflicts *errPortMappingConflicts
+			if errors.As(err, &errPortMappingConflicts) {
+				return apierror.New(http.StatusConflict, "PORT_MAPPINGS_EXIST", err.Error())
+			}
 			return err
 		}
 	}

internal/workspace/workspace_manager.go

@@ -347,9 +347,23 @@ func (mgr workspaceManager) addPortMappings(ctx context.Context, workspace *work
 		return err
 	}
 
+	var conflictErr errPortMappingConflicts
+
 	for i := range portMappings {
-		portMappings[i].WorkspaceID = workspace.ID
-		mgr.reverseProxy.AddEntry(portMappings[i].Subdomain, urls[i])
+		err = mgr.reverseProxy.AddEntry(portMappings[i].Subdomain, urls[i])
+		if err != nil {
+			if errors.Is(err, reverseproxy.ErrPortMappingConflict) {
+				conflictErr.conflicts = append(conflictErr.conflicts, portMappings[i].Subdomain)
+			} else {
+				return err
+			}
+		} else {
+			portMappings[i].WorkspaceID = workspace.ID
+		}
+	}
+
+	if len(conflictErr.conflicts) > 0 {
+		return &conflictErr
 	}
 
 	_, err = tx.NewInsert().Model(&portMappings).Exec(ctx)

web/src/workspaces/api.ts

@@ -165,7 +165,7 @@ function useDeleteWorkspace() {
 }
 
 function useAddWorkspacePort() {
-	const [status, setStatus] = useState<QueryStatus>({ type: "idle" });
+	const [status, setStatus] = useState<QueryStatus<ApiError>>({ type: "idle" });
 	const { mutate } = useSWRConfig();
 
 	const addWorkspacePort = useCallback(
@@ -191,7 +191,7 @@ function useAddWorkspacePort() {
 				);
 				setStatus({ type: "ok" });
 			} catch (error: unknown) {
-				setStatus({ type: "error", error });
+				setStatus({ type: "error", error: error as ApiError });
 			}
 		},
 		[mutate],

web/src/workspaces/workspace-port-info-tab.tsx

@@ -94,6 +94,7 @@ const NewPortMappingForm = object({
 
 function NewPortMappingRow() {
 	const { addWorkspacePort, status } = useAddWorkspacePort();
+	const { toast } = useToast();
 	const workspace = useContext(WorkspaceTableRowContext);
 	const isAddingPort = useStore((state) => state.isAddingPort);
 	const setIsAddingPort = useStore((state) => state.setIsAddingPort);
@@ -107,6 +108,42 @@ function NewPortMappingRow() {
 		},
 	});
 
+	useEffect(() => {
+		switch (status.type) {
+			case "error":
+				switch (status.error.type) {
+					case "CONFLICT":
+						toast({
+							variant: "destructive",
+							title: "Subdomain already in use!",
+							description: "Please use another subdomain for this port.",
+						});
+						break;
+
+					case "NETWORK":
+						toast({
+							variant: "destructive",
+							title: "Failed to forward port.",
+							description: "Network error.",
+						});
+						break;
+
+					default:
+						toast({
+							variant: "destructive",
+							title: "Failed to forward port.",
+							description: "Unkown error.",
+						});
+						break;
+				}
+				break;
+
+			case "ok":
+				setIsAddingPort(false);
+				break;
+		}
+	}, [status]);
+
 	if (!isAddingPort) {
 		return null;
 	}
@@ -118,7 +155,6 @@ function NewPortMappingRow() {
 				port: values.port,
 			},
 		]);
-		setIsAddingPort(false);
 	}
 
 	return (