[rush-serve-plugin] Allow serving single files

common/changes/@rushstack/rush-serve-plugin/serve-file_2022-10-03-22-06.json

@@ -0,0 +1,10 @@
+{
+  "changes": [
+    {
+      "packageName": "@rushstack/rush-serve-plugin",
+      "comment": "Allow serving of single files, e.g. to serve a specific file at \"/\" (the root).",
+      "type": "minor"
+    }
+  ],
+  "packageName": "@rushstack/rush-serve-plugin"
+}

rush-plugins/rush-serve-plugin/src/RushProjectServeConfigFile.ts

@@ -12,13 +12,25 @@ export interface IRushProjectServeJson {
   routing: IRoutingRuleJson[];
 }
 
-export interface IRoutingRuleJson {
-  projectRelativeFolder: string;
+export interface IBaseRoutingRuleJson {
   servePath: string;
   immutable?: boolean;
 }
 
+export interface IRoutingFolderRuleJson extends IBaseRoutingRuleJson {
+  projectRelativeFile: undefined;
+  projectRelativeFolder: string;
+}
+
+export interface IRoutingFileRuleJson extends IBaseRoutingRuleJson {
+  projectRelativeFile: string;
+  projectRelativeFolder: undefined;
+}
+
+export type IRoutingRuleJson = IRoutingFileRuleJson | IRoutingFolderRuleJson;
+
 export interface IRoutingRule {
+  type: 'file' | 'folder';
   diskPath: string;
   servePath: string;
   immutable: boolean;
@@ -61,8 +73,11 @@ export class RushServeConfiguration {
           );
         if (serveJson) {
           for (const rule of serveJson.routing) {
+            const { projectRelativeFile, projectRelativeFolder } = rule;
+            const diskPath: string = projectRelativeFolder ?? projectRelativeFile;
             rules.push({
-              diskPath: path.resolve(project.projectFolder, rule.projectRelativeFolder),
+              type: projectRelativeFile ? 'file' : 'folder',
+              diskPath: path.resolve(project.projectFolder, diskPath),
               servePath: rule.servePath,
               immutable: !!rule.immutable
             });

rush-plugins/rush-serve-plugin/src/phasedCommandHandler.ts

@@ -89,22 +89,44 @@ export async function phasedCommandHandler(options: IPhasedCommandHandlerOptions
         logger.terminal
       );
 
-      function setHeaders(response: express.Response, path: string, stat: unknown): void {
+      const fileRoutingRules: Map<string, IRoutingRule> = new Map();
+
+      function setHeaders(response: express.Response, path?: string, stat?: unknown): void {
         response.set('Access-Control-Allow-Origin', '*');
-        response.set('Access-Control-Allow-Methods', 'GET');
+        response.set('Access-Control-Allow-Methods', 'GET, OPTIONS');
       }
 
       for (const rule of routingRules) {
-        app.use(
-          rule.servePath,
-          express.static(rule.diskPath, {
-            dotfiles: 'ignore',
-            immutable: rule.immutable,
-            index: false,
-            redirect: false,
-            setHeaders
-          })
-        );
+        const { diskPath, servePath } = rule;
+        if (rule.type === 'file') {
+          const existingRule: IRoutingRule | undefined = fileRoutingRules.get(servePath);
+          if (existingRule) {
+            throw new Error(
+              `Request to serve "${diskPath}" at "${servePath}" conflicts with existing rule to serve "${existingRule.diskPath}" from this location.`
+            );
+          } else {
+            fileRoutingRules.set(diskPath, rule);
+            app.get(servePath, (request: express.Request, response: express.Response) => {
+              response.sendFile(diskPath, {
+                headers: {
+                  'Access-Control-Allow-Origin': '*',
+                  'Access-Control-Allow-Methods': 'GET, OPTIONS'
+                }
+              });
+            });
+          }
+        } else {
+          app.use(
+            servePath,
+            express.static(diskPath, {
+              dotfiles: 'ignore',
+              immutable: rule.immutable,
+              index: false,
+              redirect: false,
+              setHeaders
+            })
+          );
+        }
       }
 
       const server: https.Server = https.createServer(

rush-plugins/rush-serve-plugin/src/schemas/rush-project-serve.schema.json

@@ -20,25 +20,50 @@
       "type": "array",
       "description": "Routing rules",
       "items": {
-        "type": "object",
-        "additionalProperties": false,
-        "required": ["projectRelativeFolder", "servePath"],
-        "properties": {
-          "projectRelativeFolder": {
-            "type": "string",
-            "description": "The folder from which to read assets, relative to the root of the current project."
-          },
+        "oneOf": [
+          {
+            "type": "object",
+            "additionalProperties": false,
+            "required": ["projectRelativeFolder", "servePath"],
+            "properties": {
+              "projectRelativeFolder": {
+                "type": "string",
+                "description": "The folder from which to read assets, relative to the root of the current project."
+              },
+
+              "servePath": {
+                "type": "string",
+                "description": "The server path at which to serve the assets in \"projectRelativeFolder\"."
+              },
 
-          "servePath": {
-            "type": "string",
-            "description": "The server path at which to serve the assets in \"projectRelativeFolder\"."
+              "immutable": {
+                "type": "boolean",
+                "description": "Enables or disables the `immutable` directive in the `Cache-Control` resoponse header. See (https://expressjs.com/en/4x/api.html#express.static)."
+              }
+            }
           },
+          {
+            "type": "object",
+            "additionalProperties": false,
+            "required": ["projectRelativeFile", "servePath"],
+            "properties": {
+              "projectRelativeFile": {
+                "type": "string",
+                "description": "The file to serve, relative to the root of the current project."
+              },
+
+              "servePath": {
+                "type": "string",
+                "description": "The server path at which to serve \"projectRelativeFile\"."
+              },
 
-          "immutable": {
-            "type": "boolean",
-            "description": "Enables or disables the `immutable` directive in the `Cache-Control` resoponse header. See (https://expressjs.com/en/4x/api.html#express.static)."
+              "immutable": {
+                "type": "boolean",
+                "description": "Enables or disables the `immutable` directive in the `Cache-Control` resoponse header. See (https://expressjs.com/en/4x/api.html#express.static)."
+              }
+            }
           }
-        }
+        ]
       }
     }
   }