caddyconfig: cancel HTTP loader requests with context (#7918)

caddyconfig/httploader.go

@@ -95,7 +95,7 @@ func (hl HTTPLoader) LoadConfig(ctx caddy.Context) ([]byte, error) {
 	}
 
 	url := repl.ReplaceAll(hl.URL, "")
-	req, err := http.NewRequest(method, url, nil)
+	req, err := http.NewRequestWithContext(ctx, method, url, nil)
 	if err != nil {
 		return nil, err
 	}

caddyconfig/httploader_test.go

@@ -0,0 +1,76 @@
+// Copyright 2015 Matthew Holt and The Caddy Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package caddyconfig
+
+import (
+	"context"
+	"errors"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+	"time"
+
+	"github.com/caddyserver/caddy/v2"
+)
+
+func TestHTTPLoaderLoadConfigRespectsContextCancellation(t *testing.T) {
+	requestStarted := make(chan struct{})
+	requestCanceled := make(chan struct{})
+	stopServer := make(chan struct{})
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		close(requestStarted)
+		select {
+		case <-r.Context().Done():
+			close(requestCanceled)
+		case <-stopServer:
+		}
+	}))
+	t.Cleanup(func() {
+		close(stopServer)
+		srv.Close()
+	})
+
+	ctx, cancel := caddy.NewContext(caddy.Context{Context: context.Background()})
+	loader := HTTPLoader{URL: srv.URL}
+
+	errCh := make(chan error, 1)
+	go func() {
+		_, err := loader.LoadConfig(ctx)
+		errCh <- err
+	}()
+
+	select {
+	case <-requestStarted:
+	case <-time.After(time.Second):
+		t.Fatal("request did not reach test server")
+	}
+
+	cancel()
+
+	select {
+	case err := <-errCh:
+		if !errors.Is(err, context.Canceled) {
+			t.Fatalf("expected context cancellation error, got %v", err)
+		}
+	case <-time.After(time.Second):
+		t.Fatal("LoadConfig did not return after context cancellation")
+	}
+
+	select {
+	case <-requestCanceled:
+	case <-time.After(time.Second):
+		t.Fatal("request context was not canceled")
+	}
+}