Server: Write internal server error on missing write (#57813)

pkg/web/context.go

@@ -22,6 +22,9 @@ import (
 	"net/url"
 	"strconv"
 	"strings"
+
+	"github.com/grafana/grafana/pkg/util/errutil"
+	"github.com/grafana/grafana/pkg/util/errutil/errhttp"
 )
 
 // Context represents the runtime context of current request of Macaron instance.
@@ -34,6 +37,8 @@ type Context struct {
 	template *template.Template
 }
 
+var errMissingWrite = errutil.NewBase(errutil.StatusInternal, "web.missingWrite")
+
 func (ctx *Context) run() {
 	h := http.Handler(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {}))
 	for i := len(ctx.mws) - 1; i >= 0; i-- {
@@ -47,7 +52,11 @@ func (ctx *Context) run() {
 	// This indicates nearly always that a middleware is misbehaving and not calling its next.ServeHTTP().
 	// In rare cases where a blank http.StatusOK without any body is wished, explicitly state that using w.WriteStatus(http.StatusOK)
 	if !rw.Written() {
-		panic("chain did not write HTTP response")
+		errhttp.Write(
+			ctx.Req.Context(),
+			errMissingWrite.Errorf("chain did not write HTTP response: %s", ctx.Req.URL.Path),
+			rw,
+		)
 	}
 }
 

pkg/web/context_test.go

@@ -2,8 +2,11 @@ package web
 
 import (
 	"net/http"
+	"net/http/httptest"
 	"testing"
 
+	"github.com/stretchr/testify/assert"
+
 	"github.com/grafana/grafana/pkg/infra/log"
 )
 
@@ -94,3 +97,17 @@ func TestContext_RemoteAddr(t *testing.T) {
 		})
 	}
 }
+
+func TestContext_noHandler(t *testing.T) {
+	recorder := httptest.NewRecorder()
+
+	method := http.MethodGet
+	c := &Context{
+		Req:  httptest.NewRequest(method, "/", nil),
+		Resp: NewResponseWriter(method, recorder),
+	}
+
+	c.run()
+
+	assert.Equal(t, http.StatusInternalServerError, recorder.Code)
+}