Refactor to use httputil.ReverseProxy (#342)

* Refactor to use httputil.ReverseProxy

Refactor manual HTTP proxying logic in Process.ProxyRequest to use the standard
library's httputil.ReverseProxy.

* Refactor TestProcess_ForceStopWithKill test

Update to handle behavior with httputil.ReverseProxy.

* Fix gin interface conversion panic

proxy/config/config.go

@@ -3,6 +3,7 @@ package config
 import (
 	"fmt"
 	"io"
+	"net/url"
 	"os"
 	"regexp"
 	"runtime"
@@ -342,6 +343,13 @@ func LoadConfigFromReader(r io.Reader) (Config, error) {
 			}
 		}
 
+		// Validate the proxy URL.
+		if _, err := url.Parse(modelConfig.Proxy); err != nil {
+			return Config{}, fmt.Errorf(
+				"model %s: invalid proxy URL: %w", modelId, err,
+			)
+		}
+
 		config.Models[modelId] = modelConfig
 	}
 

proxy/process.go

@@ -4,12 +4,11 @@ import (
 	"context"
 	"errors"
 	"fmt"
-	"io"
 	"net"
 	"net/http"
+	"net/http/httputil"
 	"net/url"
 	"os/exec"
-	"strconv"
 	"strings"
 	"sync"
 	"sync/atomic"
@@ -40,9 +39,10 @@ const (
 )
 
 type Process struct {
-	ID     string
+	ID           string
-	config config.ModelConfig
+	config       config.ModelConfig
-	cmd    *exec.Cmd
+	cmd          *exec.Cmd
+	reverseProxy *httputil.ReverseProxy
 
 	// PR #155 called to cancel the upstream process
 	cmdMutex       sync.RWMutex
@@ -85,10 +85,29 @@ func NewProcess(ID string, healthCheckTimeout int, config config.ModelConfig, pr
 		concurrentLimit = config.ConcurrencyLimit
 	}
 
+	// Setup the reverse proxy.
+	proxyURL, err := url.Parse(config.Proxy)
+	if err != nil {
+		proxyLogger.Errorf("<%s> invalid proxy URL %q: %v", ID, config.Proxy, err)
+	}
+
+	var reverseProxy *httputil.ReverseProxy
+	if proxyURL != nil {
+		reverseProxy = httputil.NewSingleHostReverseProxy(proxyURL)
+		reverseProxy.ModifyResponse = func(resp *http.Response) error {
+			// prevent nginx from buffering streaming responses (e.g., SSE)
+			if strings.Contains(strings.ToLower(resp.Header.Get("Content-Type")), "text/event-stream") {
+				resp.Header.Set("X-Accel-Buffering", "no")
+			}
+			return nil
+		}
+	}
+
 	return &Process{
 		ID:                      ID,
 		config:                  config,
 		cmd:                     nil,
+		reverseProxy:            reverseProxy,
 		cancelUpstream:          nil,
 		processLogger:           processLogger,
 		proxyLogger:             proxyLogger,
@@ -480,56 +499,10 @@ func (p *Process) ProxyRequest(w http.ResponseWriter, r *http.Request) {
 		startDuration = time.Since(beginStartTime)
 	}
 
-	proxyTo := p.config.Proxy
+	if p.reverseProxy != nil {
-	client := &http.Client{}
+		p.reverseProxy.ServeHTTP(w, r)
-	req, err := http.NewRequestWithContext(r.Context(), r.Method, proxyTo+r.URL.String(), r.Body)
+	} else {
-	if err != nil {
+		http.Error(w, fmt.Sprintf("No reverse proxy available for %s", p.ID), http.StatusInternalServerError)
-		http.Error(w, err.Error(), http.StatusInternalServerError)
-		return
-	}
-	req.Header = r.Header.Clone()
-
-	contentLength, err := strconv.ParseInt(req.Header.Get("content-length"), 10, 64)
-	if err == nil {
-		req.ContentLength = contentLength
-	}
-
-	resp, err := client.Do(req)
-	if err != nil {
-		http.Error(w, err.Error(), http.StatusBadGateway)
-		return
-	}
-	defer resp.Body.Close()
-	for k, vv := range resp.Header {
-		for _, v := range vv {
-			w.Header().Add(k, v)
-		}
-	}
-	// prevent nginx from buffering streaming responses (e.g., SSE)
-	if strings.Contains(strings.ToLower(resp.Header.Get("Content-Type")), "text/event-stream") {
-		w.Header().Set("X-Accel-Buffering", "no")
-	}
-	w.WriteHeader(resp.StatusCode)
-
-	// faster than io.Copy when streaming
-	buf := make([]byte, 32*1024)
-	for {
-		n, err := resp.Body.Read(buf)
-		if n > 0 {
-			if _, writeErr := w.Write(buf[:n]); writeErr != nil {
-				return
-			}
-			if flusher, ok := w.(http.Flusher); ok {
-				flusher.Flush()
-			}
-		}
-		if err == io.EOF {
-			break
-		}
-		if err != nil {
-			http.Error(w, err.Error(), http.StatusBadGateway)
-			return
-		}
 	}
 
 	totalTime := time.Since(requestBeginTime)

proxy/process_test.go

@@ -436,7 +436,9 @@ func TestProcess_ForceStopWithKill(t *testing.T) {
 		if runtime.GOOS == "windows" {
 			assert.Contains(t, w.Body.String(), "wsarecv: An existing connection was forcibly closed by the remote host")
 		} else {
-			assert.Contains(t, w.Body.String(), "unexpected EOF")
+			// Upstream may be killed mid-response.
+			// Assert an incomplete or partial response.
+			assert.NotEqual(t, "12345", w.Body.String())
 		}
 
 		close(waitChan)

proxy/proxymanager_test.go

@@ -21,6 +21,32 @@ import (
 	"github.com/tidwall/gjson"
 )
 
+// TestResponseRecorder adds CloseNotify to httptest.ResponseRecorder.
+// "If you want to write your own tests around streams you will need a Recorder that can handle CloseNotifier."
+// The tests can panic otherwise:
+// panic: interface conversion: *httptest.ResponseRecorder is not http.CloseNotifier: missing method CloseNotify
+// See: https://github.com/gin-gonic/gin/issues/1815
+// TestResponseRecorder is taken from gin's own tests: https://github.com/gin-gonic/gin/blob/ce20f107f5dc498ec7489d7739541a25dcd48463/context_test.go#L1747-L1765
+type TestResponseRecorder struct {
+	*httptest.ResponseRecorder
+	closeChannel chan bool
+}
+
+func (r *TestResponseRecorder) CloseNotify() <-chan bool {
+	return r.closeChannel
+}
+
+func (r *TestResponseRecorder) closeClient() {
+	r.closeChannel <- true
+}
+
+func CreateTestResponseRecorder() *TestResponseRecorder {
+	return &TestResponseRecorder{
+		httptest.NewRecorder(),
+		make(chan bool, 1),
+	}
+}
+
 func TestProxyManager_SwapProcessCorrectly(t *testing.T) {
 	config := config.AddDefaultGroupToConfig(config.Config{
 		HealthCheckTimeout: 15,
@@ -37,7 +63,7 @@ func TestProxyManager_SwapProcessCorrectly(t *testing.T) {
 	for _, modelName := range []string{"model1", "model2"} {
 		reqBody := fmt.Sprintf(`{"model":"%s"}`, modelName)
 		req := httptest.NewRequest("POST", "/v1/chat/completions", bytes.NewBufferString(reqBody))
-		w := httptest.NewRecorder()
+		w := CreateTestResponseRecorder()
 
 		proxy.ServeHTTP(w, req)
 		assert.Equal(t, http.StatusOK, w.Code)
@@ -74,7 +100,7 @@ func TestProxyManager_SwapMultiProcess(t *testing.T) {
 		t.Run(requestedModel, func(t *testing.T) {
 			reqBody := fmt.Sprintf(`{"model":"%s"}`, requestedModel)
 			req := httptest.NewRequest("POST", "/v1/chat/completions", bytes.NewBufferString(reqBody))
-			w := httptest.NewRecorder()
+			w := CreateTestResponseRecorder()
 
 			proxy.ServeHTTP(w, req)
 			assert.Equal(t, http.StatusOK, w.Code)
@@ -116,7 +142,7 @@ func TestProxyManager_PersistentGroupsAreNotSwapped(t *testing.T) {
 	for _, requestedModel := range tests {
 		reqBody := fmt.Sprintf(`{"model":"%s"}`, requestedModel)
 		req := httptest.NewRequest("POST", "/v1/chat/completions", bytes.NewBufferString(reqBody))
-		w := httptest.NewRecorder()
+		w := CreateTestResponseRecorder()
 
 		proxy.ServeHTTP(w, req)
 		assert.Equal(t, http.StatusOK, w.Code)
@@ -159,7 +185,7 @@ func TestProxyManager_SwapMultiProcessParallelRequests(t *testing.T) {
 
 			reqBody := fmt.Sprintf(`{"model":"%s"}`, key)
 			req := httptest.NewRequest("POST", "/v1/chat/completions?wait=1000ms", bytes.NewBufferString(reqBody))
-			w := httptest.NewRecorder()
+			w := CreateTestResponseRecorder()
 
 			proxy.ServeHTTP(w, req)
 
@@ -212,7 +238,7 @@ func TestProxyManager_ListModelsHandler(t *testing.T) {
 	// Create a test request
 	req := httptest.NewRequest("GET", "/v1/models", nil)
 	req.Header.Add("Origin", "i-am-the-origin")
-	w := httptest.NewRecorder()
+	w := CreateTestResponseRecorder()
 
 	// Call the listModelsHandler
 	proxy.ServeHTTP(w, req)
@@ -311,7 +337,7 @@ models:
 	proxy := New(processedConfig)
 
 	req := httptest.NewRequest("GET", "/v1/models", nil)
-	w := httptest.NewRecorder()
+	w := CreateTestResponseRecorder()
 	proxy.ServeHTTP(w, req)
 
 	assert.Equal(t, http.StatusOK, w.Code)
@@ -387,7 +413,7 @@ func TestProxyManager_ListModelsHandler_SortedByID(t *testing.T) {
 
 	// Request models list
 	req := httptest.NewRequest("GET", "/v1/models", nil)
-	w := httptest.NewRecorder()
+	w := CreateTestResponseRecorder()
 	proxy.ServeHTTP(w, req)
 
 	assert.Equal(t, http.StatusOK, w.Code)
@@ -448,7 +474,7 @@ func TestProxyManager_Shutdown(t *testing.T) {
 			defer wg.Done()
 			reqBody := fmt.Sprintf(`{"model":"%s"}`, modelName)
 			req := httptest.NewRequest("POST", "/v1/chat/completions", bytes.NewBufferString(reqBody))
-			w := httptest.NewRecorder()
+			w := CreateTestResponseRecorder()
 
 			// send a request to trigger the proxy to load ... this should hang waiting for start up
 			proxy.ServeHTTP(w, req)
@@ -476,12 +502,12 @@ func TestProxyManager_Unload(t *testing.T) {
 	proxy := New(conf)
 	reqBody := fmt.Sprintf(`{"model":"%s"}`, "model1")
 	req := httptest.NewRequest("POST", "/v1/chat/completions", bytes.NewBufferString(reqBody))
-	w := httptest.NewRecorder()
+	w := CreateTestResponseRecorder()
 	proxy.ServeHTTP(w, req)
 
 	assert.Equal(t, proxy.processGroups[config.DEFAULT_GROUP_ID].processes["model1"].CurrentState(), StateReady)
 	req = httptest.NewRequest("GET", "/unload", nil)
-	w = httptest.NewRecorder()
+	w = CreateTestResponseRecorder()
 	proxy.ServeHTTP(w, req)
 	assert.Equal(t, http.StatusOK, w.Code)
 	assert.Equal(t, w.Body.String(), "OK")
@@ -519,7 +545,7 @@ func TestProxyManager_UnloadSingleModel(t *testing.T) {
 	for _, modelName := range []string{"model1", "model2"} {
 		reqBody := fmt.Sprintf(`{"model":"%s"}`, modelName)
 		req := httptest.NewRequest("POST", "/v1/chat/completions", bytes.NewBufferString(reqBody))
-		w := httptest.NewRecorder()
+		w := CreateTestResponseRecorder()
 		proxy.ServeHTTP(w, req)
 	}
 
@@ -527,7 +553,7 @@ func TestProxyManager_UnloadSingleModel(t *testing.T) {
 	assert.Equal(t, StateReady, proxy.processGroups[testGroupId].processes["model2"].CurrentState())
 
 	req := httptest.NewRequest("POST", "/api/models/unload/model1", nil)
-	w := httptest.NewRecorder()
+	w := CreateTestResponseRecorder()
 	proxy.ServeHTTP(w, req)
 	assert.Equal(t, http.StatusOK, w.Code)
 	if !assert.Equal(t, w.Body.String(), "OK") {
@@ -571,7 +597,7 @@ func TestProxyManager_RunningEndpoint(t *testing.T) {
 
 	t.Run("no models loaded", func(t *testing.T) {
 		req := httptest.NewRequest("GET", "/running", nil)
-		w := httptest.NewRecorder()
+		w := CreateTestResponseRecorder()
 		proxy.ServeHTTP(w, req)
 
 		assert.Equal(t, http.StatusOK, w.Code)
@@ -589,13 +615,13 @@ func TestProxyManager_RunningEndpoint(t *testing.T) {
 		// Load just a model.
 		reqBody := `{"model":"model1"}`
 		req := httptest.NewRequest("POST", "/v1/chat/completions", bytes.NewBufferString(reqBody))
-		w := httptest.NewRecorder()
+		w := CreateTestResponseRecorder()
 		proxy.ServeHTTP(w, req)
 		assert.Equal(t, http.StatusOK, w.Code)
 
 		// Simulate browser call for the `/running` endpoint.
 		req = httptest.NewRequest("GET", "/running", nil)
-		w = httptest.NewRecorder()
+		w = CreateTestResponseRecorder()
 		proxy.ServeHTTP(w, req)
 
 		var response RunningResponse
@@ -647,7 +673,7 @@ func TestProxyManager_AudioTranscriptionHandler(t *testing.T) {
 	// Create the request with the multipart form data
 	req := httptest.NewRequest("POST", "/v1/audio/transcriptions", &b)
 	req.Header.Set("Content-Type", w.FormDataContentType())
-	rec := httptest.NewRecorder()
+	rec := CreateTestResponseRecorder()
 	proxy.ServeHTTP(rec, req)
 
 	// Verify the response
@@ -682,7 +708,7 @@ func TestProxyManager_UseModelName(t *testing.T) {
 	t.Run("useModelName over rides requested model: /v1/chat/completions", func(t *testing.T) {
 		reqBody := fmt.Sprintf(`{"model":"%s"}`, requestedModel)
 		req := httptest.NewRequest("POST", "/v1/chat/completions", bytes.NewBufferString(reqBody))
-		w := httptest.NewRecorder()
+		w := CreateTestResponseRecorder()
 
 		proxy.ServeHTTP(w, req)
 		assert.Equal(t, http.StatusOK, w.Code)
@@ -716,7 +742,7 @@ func TestProxyManager_UseModelName(t *testing.T) {
 		// Create the request with the multipart form data
 		req := httptest.NewRequest("POST", "/v1/audio/transcriptions", &b)
 		req.Header.Set("Content-Type", w.FormDataContentType())
-		rec := httptest.NewRecorder()
+		rec := CreateTestResponseRecorder()
 		proxy.ServeHTTP(rec, req)
 
 		// Verify the response
@@ -784,7 +810,7 @@ func TestProxyManager_CORSOptionsHandler(t *testing.T) {
 				req.Header.Set(k, v)
 			}
 
-			w := httptest.NewRecorder()
+			w := CreateTestResponseRecorder()
 			proxy.ServeHTTP(w, req)
 
 			assert.Equal(t, tt.expectedStatus, w.Code)
@@ -812,7 +838,7 @@ models:
 	defer proxy.StopProcesses(StopWaitForInflightRequest)
 	t.Run("main model name", func(t *testing.T) {
 		req := httptest.NewRequest("GET", "/upstream/model1/test", nil)
-		rec := httptest.NewRecorder()
+		rec := CreateTestResponseRecorder()
 		proxy.ServeHTTP(rec, req)
 		assert.Equal(t, http.StatusOK, rec.Code)
 		assert.Equal(t, "model1", rec.Body.String())
@@ -820,7 +846,7 @@ models:
 
 	t.Run("model alias", func(t *testing.T) {
 		req := httptest.NewRequest("GET", "/upstream/model-alias/test", nil)
-		rec := httptest.NewRecorder()
+		rec := CreateTestResponseRecorder()
 		proxy.ServeHTTP(rec, req)
 		assert.Equal(t, http.StatusOK, rec.Code)
 		assert.Equal(t, "model1", rec.Body.String())
@@ -841,7 +867,7 @@ func TestProxyManager_ChatContentLength(t *testing.T) {
 
 	reqBody := fmt.Sprintf(`{"model":"%s", "x": "this is just some content to push the length out a bit"}`, "model1")
 	req := httptest.NewRequest("POST", "/v1/chat/completions", bytes.NewBufferString(reqBody))
-	w := httptest.NewRecorder()
+	w := CreateTestResponseRecorder()
 
 	proxy.ServeHTTP(w, req)
 	assert.Equal(t, http.StatusOK, w.Code)
@@ -869,7 +895,7 @@ func TestProxyManager_FiltersStripParams(t *testing.T) {
 	defer proxy.StopProcesses(StopWaitForInflightRequest)
 	reqBody := `{"model":"model1", "temperature":0.1, "x_param":"123", "y_param":"abc", "stream":true}`
 	req := httptest.NewRequest("POST", "/v1/chat/completions", bytes.NewBufferString(reqBody))
-	w := httptest.NewRecorder()
+	w := CreateTestResponseRecorder()
 
 	proxy.ServeHTTP(w, req)
 	assert.Equal(t, http.StatusOK, w.Code)
@@ -900,7 +926,7 @@ func TestProxyManager_MiddlewareWritesMetrics_NonStreaming(t *testing.T) {
 	// Make a non-streaming request
 	reqBody := `{"model":"model1", "stream": false}`
 	req := httptest.NewRequest("POST", "/v1/chat/completions", bytes.NewBufferString(reqBody))
-	w := httptest.NewRecorder()
+	w := CreateTestResponseRecorder()
 
 	proxy.ServeHTTP(w, req)
 	assert.Equal(t, http.StatusOK, w.Code)
@@ -935,7 +961,7 @@ func TestProxyManager_MiddlewareWritesMetrics_Streaming(t *testing.T) {
 	// Make a streaming request
 	reqBody := `{"model":"model1", "stream": true}`
 	req := httptest.NewRequest("POST", "/v1/chat/completions?stream=true", bytes.NewBufferString(reqBody))
-	w := httptest.NewRecorder()
+	w := CreateTestResponseRecorder()
 
 	proxy.ServeHTTP(w, req)
 	assert.Equal(t, http.StatusOK, w.Code)
@@ -967,7 +993,7 @@ func TestProxyManager_HealthEndpoint(t *testing.T) {
 	proxy := New(config)
 	defer proxy.StopProcesses(StopWaitForInflightRequest)
 	req := httptest.NewRequest("GET", "/health", nil)
-	rec := httptest.NewRecorder()
+	rec := CreateTestResponseRecorder()
 	proxy.ServeHTTP(rec, req)
 	assert.Equal(t, http.StatusOK, rec.Code)
 	assert.Equal(t, "OK", rec.Body.String())
@@ -988,7 +1014,7 @@ func TestProxyManager_CompletionEndpoint(t *testing.T) {
 
 	reqBody := `{"model":"model1"}`
 	req := httptest.NewRequest("POST", "/completion", bytes.NewBufferString(reqBody))
-	w := httptest.NewRecorder()
+	w := CreateTestResponseRecorder()
 
 	proxy.ServeHTTP(w, req)
 	assert.Equal(t, http.StatusOK, w.Code)
@@ -1080,7 +1106,7 @@ func TestProxyManager_StreamingEndpointsReturnNoBufferingHeader(t *testing.T) {
 
 			req := httptest.NewRequest("GET", endpoint, nil)
 			req = req.WithContext(ctx)
-			rec := httptest.NewRecorder()
+			rec := CreateTestResponseRecorder()
 
 			// Run handler in goroutine and wait for context timeout
 			done := make(chan struct{})
@@ -1119,7 +1145,7 @@ func TestProxyManager_ProxiedStreamingEndpointReturnsNoBufferingHeader(t *testin
 	reqBody := `{"model":"streaming-model"}`
 	// simple-responder will return text/event-stream when stream=true is in the query
 	req := httptest.NewRequest("POST", "/v1/chat/completions?stream=true", bytes.NewBufferString(reqBody))
-	rec := httptest.NewRecorder()
+	rec := CreateTestResponseRecorder()
 
 	proxy.ServeHTTP(rec, req)