fix #2851: implement HTTP HEAD requests

evanw · Jan 19, 2023 · f48391a · f48391a
1 parent 7c0526e
commit f48391a
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diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -1,5 +1,11 @@
 # Changelog
 
+## Unreleased
+
+* Implement HTTP `HEAD` requests in serve mode ([#2851](https://github.com/evanw/esbuild/issues/2851))
+
+    Previously esbuild's serve mode only responded to HTTP `GET` requests. With this release, esbuild's serve mode will also respond to HTTP `HEAD` requests, which are just like HTTP `GET` requests except that the body of the response is omitted.
+
 ## 0.17.3
 
 * Fix incorrect CSS minification for certain rules ([#2838](https://github.com/evanw/esbuild/issues/2838))

diff --git a/pkg/api/serve_other.go b/pkg/api/serve_other.go
@@ -125,8 +125,15 @@ func (h *apiHandler) ServeHTTP(res http.ResponseWriter, req *http.Request) {
 		return
 	}
 
-	// Handle get requests
-	if req.Method == "GET" && strings.HasPrefix(req.URL.Path, "/") {
+	// HEAD requests omit the body
+	maybeWriteResponseBody := func(bytes []byte) { res.Write(bytes) }
+	isHEAD := req.Method == "HEAD"
+	if isHEAD {
+		maybeWriteResponseBody = func(bytes []byte) { res.Write(nil) }
+	}
+
+	// Handle GET and HEAD requests
+	if (isHEAD || req.Method == "GET") && strings.HasPrefix(req.URL.Path, "/") {
 		res.Header().Set("Access-Control-Allow-Origin", "*")
 		queryPath := path.Clean(req.URL.Path)[1:]
 		result := h.rebuild()
@@ -136,7 +143,7 @@ func (h *apiHandler) ServeHTTP(res http.ResponseWriter, req *http.Request) {
 			res.Header().Set("Content-Type", "text/plain; charset=utf-8")
 			go h.notifyRequest(time.Since(start), req, http.StatusServiceUnavailable)
 			res.WriteHeader(http.StatusServiceUnavailable)
-			res.Write([]byte(errorsToString(result.Errors)))
+			maybeWriteResponseBody([]byte(errorsToString(result.Errors)))
 			return
 		}
 
@@ -186,7 +193,7 @@ func (h *apiHandler) ServeHTTP(res http.ResponseWriter, req *http.Request) {
 								// insensitive check because some file systems are case-sensitive.
 								go h.notifyRequest(time.Since(start), req, http.StatusForbidden)
 								res.WriteHeader(http.StatusForbidden)
-								res.Write([]byte("403 - Forbidden"))
+								maybeWriteResponseBody([]byte("403 - Forbidden"))
 								return
 							}
 						}
@@ -197,7 +204,7 @@ func (h *apiHandler) ServeHTTP(res http.ResponseWriter, req *http.Request) {
 						} else if err != syscall.ENOENT {
 							go h.notifyRequest(time.Since(start), req, http.StatusInternalServerError)
 							res.WriteHeader(http.StatusInternalServerError)
-							res.Write([]byte(fmt.Sprintf("500 - Internal server error: %s", err.Error())))
+							maybeWriteResponseBody([]byte(fmt.Sprintf("500 - Internal server error: %s", err.Error())))
 							return
 						}
 					}
@@ -225,7 +232,7 @@ func (h *apiHandler) ServeHTTP(res http.ResponseWriter, req *http.Request) {
 			} else if err != syscall.ENOENT {
 				go h.notifyRequest(time.Since(start), req, http.StatusInternalServerError)
 				res.WriteHeader(http.StatusInternalServerError)
-				res.Write([]byte(fmt.Sprintf("500 - Internal server error: %s", err.Error())))
+				maybeWriteResponseBody([]byte(fmt.Sprintf("500 - Internal server error: %s", err.Error())))
 				return
 			}
 		}
@@ -235,7 +242,7 @@ func (h *apiHandler) ServeHTTP(res http.ResponseWriter, req *http.Request) {
 			res.Header().Set("Location", req.URL.Path+"/")
 			go h.notifyRequest(time.Since(start), req, http.StatusFound)
 			res.WriteHeader(http.StatusFound)
-			res.Write(nil)
+			maybeWriteResponseBody(nil)
 			return
 		}
 
@@ -249,7 +256,7 @@ func (h *apiHandler) ServeHTTP(res http.ResponseWriter, req *http.Request) {
 			} else if err != syscall.ENOENT {
 				go h.notifyRequest(time.Since(start), req, http.StatusInternalServerError)
 				res.WriteHeader(http.StatusInternalServerError)
-				res.Write([]byte(fmt.Sprintf("500 - Internal server error: %s", err.Error())))
+				maybeWriteResponseBody([]byte(fmt.Sprintf("500 - Internal server error: %s", err.Error())))
 				return
 			}
 		}
@@ -277,7 +284,7 @@ func (h *apiHandler) ServeHTTP(res http.ResponseWriter, req *http.Request) {
 			if err != nil {
 				go h.notifyRequest(time.Since(start), req, http.StatusInternalServerError)
 				res.WriteHeader(http.StatusInternalServerError)
-				res.Write([]byte(fmt.Sprintf("500 - Internal server error: %s", err.Error())))
+				maybeWriteResponseBody([]byte(fmt.Sprintf("500 - Internal server error: %s", err.Error())))
 				return
 			}
 
@@ -293,7 +300,7 @@ func (h *apiHandler) ServeHTTP(res http.ResponseWriter, req *http.Request) {
 			res.Header().Set("Content-Length", fmt.Sprintf("%d", len(fileBytes)))
 			go h.notifyRequest(time.Since(start), req, status)
 			res.WriteHeader(status)
-			res.Write(fileBytes)
+			maybeWriteResponseBody(fileBytes)
 			return
 		}
 
@@ -303,7 +310,7 @@ func (h *apiHandler) ServeHTTP(res http.ResponseWriter, req *http.Request) {
 			res.Header().Set("Content-Type", "text/html; charset=utf-8")
 			res.Header().Set("Content-Length", fmt.Sprintf("%d", len(html)))
 			go h.notifyRequest(time.Since(start), req, http.StatusOK)
-			res.Write(html)
+			maybeWriteResponseBody(html)
 			return
 		}
 	}
@@ -312,7 +319,7 @@ func (h *apiHandler) ServeHTTP(res http.ResponseWriter, req *http.Request) {
 	res.Header().Set("Content-Type", "text/plain; charset=utf-8")
 	go h.notifyRequest(time.Since(start), req, http.StatusNotFound)
 	res.WriteHeader(http.StatusNotFound)
-	res.Write([]byte("404 - Not Found"))
+	maybeWriteResponseBody([]byte("404 - Not Found"))
 }
 
 // This exposes an event stream to clients using server-sent events:

diff --git a/scripts/js-api-tests.js b/scripts/js-api-tests.js
@@ -3654,9 +3654,9 @@ import "after/alias";
   },
 }
 
-function fetch(host, port, path, { headers } = {}) {
+function fetch(host, port, path, { headers, method = 'GET' } = {}) {
   return new Promise((resolve, reject) => {
-    http.get({ host, port, path, headers }, res => {
+    http.request({ method, host, port, path, headers }, res => {
       const chunks = []
       res.on('data', chunk => chunks.push(chunk))
       res.on('end', () => {
@@ -3670,7 +3670,7 @@ function fetch(host, port, path, { headers } = {}) {
           resolve(content)
         }
       })
-    }).on('error', reject)
+    }).on('error', reject).end()
   })
 }
 
@@ -4100,9 +4100,6 @@ let serveTests = {
     await writeFileAsync(input, `console.log(123)`)
 
     let onRequest;
-    let singleRequestPromise = new Promise(resolve => {
-      onRequest = resolve;
-    });
 
     const context = await esbuild.context({
       entryPoints: [input],
@@ -4113,21 +4110,40 @@ let serveTests = {
     try {
       const result = await context.serve({
         host: '127.0.0.1',
-        onRequest,
+        onRequest: args => onRequest(args),
       })
       assert.strictEqual(result.host, '127.0.0.1');
       assert.strictEqual(typeof result.port, 'number');
 
-      const buffer = await fetch(result.host, result.port, '/in.js')
-      assert.strictEqual(buffer.toString(), `console.log(123);\n`);
-      assert.strictEqual(fs.readFileSync(input, 'utf8'), `console.log(123)`)
+      // GET /in.js
+      {
+        const singleRequestPromise = new Promise(resolve => { onRequest = resolve });
+        const buffer = await fetch(result.host, result.port, '/in.js')
+        assert.strictEqual(buffer.toString(), `console.log(123);\n`);
+        assert.strictEqual(fs.readFileSync(input, 'utf8'), `console.log(123)`)
+
+        let singleRequest = await singleRequestPromise;
+        assert.strictEqual(singleRequest.method, 'GET');
+        assert.strictEqual(singleRequest.path, '/in.js');
+        assert.strictEqual(singleRequest.status, 200);
+        assert.strictEqual(typeof singleRequest.remoteAddress, 'string');
+        assert.strictEqual(typeof singleRequest.timeInMS, 'number');
+      }
 
-      let singleRequest = await singleRequestPromise;
-      assert.strictEqual(singleRequest.method, 'GET');
-      assert.strictEqual(singleRequest.path, '/in.js');
-      assert.strictEqual(singleRequest.status, 200);
-      assert.strictEqual(typeof singleRequest.remoteAddress, 'string');
-      assert.strictEqual(typeof singleRequest.timeInMS, 'number');
+      // HEAD /in.js
+      {
+        const singleRequestPromise = new Promise(resolve => { onRequest = resolve });
+        const buffer = await fetch(result.host, result.port, '/in.js', { method: 'HEAD' })
+        assert.strictEqual(buffer.toString(), ``); // HEAD omits the content
+        assert.strictEqual(fs.readFileSync(input, 'utf8'), `console.log(123)`)
+
+        let singleRequest = await singleRequestPromise;
+        assert.strictEqual(singleRequest.method, 'HEAD');
+        assert.strictEqual(singleRequest.path, '/in.js');
+        assert.strictEqual(singleRequest.status, 200);
+        assert.strictEqual(typeof singleRequest.remoteAddress, 'string');
+        assert.strictEqual(typeof singleRequest.timeInMS, 'number');
+      }
     } finally {
       await context.dispose();
     }