K8s: Add accept header to ctx (#83802)

pkg/apiserver/builder/helper.go

@@ -20,6 +20,8 @@ import (
 	"k8s.io/apiserver/pkg/util/openapi"
 	k8sscheme "k8s.io/client-go/kubernetes/scheme"
 	"k8s.io/kube-openapi/pkg/common"
+
+	"github.com/grafana/grafana/pkg/apiserver/endpoints/filters"
 )
 
 func SetupConfig(
@@ -70,7 +72,11 @@ func SetupConfig(
 		if err != nil {
 			panic(fmt.Sprintf("could not build handler chain func: %s", err.Error()))
 		}
-		return genericapiserver.DefaultBuildHandlerChain(requestHandler, c)
+
+		handler := genericapiserver.DefaultBuildHandlerChain(requestHandler, c)
+		handler = filters.WithAcceptHeader(handler)
+
+		return handler
 	}
 
 	k8sVersion, err := getK8sApiserverVersion()

pkg/apiserver/endpoints/filters/accept.go

@@ -0,0 +1,15 @@
+package filters
+
+import (
+	"net/http"
+
+	"github.com/grafana/grafana/pkg/apiserver/endpoints/request"
+)
+
+// WithAcceptHeader adds the Accept header to the request context.
+func WithAcceptHeader(handler http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
+		ctx := request.WithAcceptHeader(req.Context(), req.Header.Get("Accept"))
+		handler.ServeHTTP(w, req.WithContext(ctx))
+	})
+}

pkg/apiserver/endpoints/filters/accept_test.go

@@ -0,0 +1,46 @@
+package filters
+
+import (
+	"context"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/grafana/grafana/pkg/apiserver/endpoints/request"
+	"github.com/stretchr/testify/require"
+)
+
+func TestWithAcceptHeader(t *testing.T) {
+	t.Run("should not set accept header in context for empty header", func(t *testing.T) {
+		req := httptest.NewRequest(http.MethodGet, "/", nil)
+
+		rr := httptest.NewRecorder()
+		handler := &fakeHandler{}
+		WithAcceptHeader(handler).ServeHTTP(rr, req)
+
+		acceptHeader, ok := request.AcceptHeaderFrom(handler.ctx)
+		require.False(t, ok)
+		require.Empty(t, acceptHeader)
+	})
+
+	t.Run("should set accept header in context", func(t *testing.T) {
+		req := httptest.NewRequest(http.MethodGet, "/", nil)
+		req.Header.Set("Accept", "application/json")
+
+		rr := httptest.NewRecorder()
+		handler := &fakeHandler{}
+		WithAcceptHeader(handler).ServeHTTP(rr, req)
+
+		acceptHeader, ok := request.AcceptHeaderFrom(handler.ctx)
+		require.True(t, ok)
+		require.Equal(t, "application/json", acceptHeader)
+	})
+}
+
+type fakeHandler struct {
+	ctx context.Context
+}
+
+func (h *fakeHandler) ServeHTTP(w http.ResponseWriter, req *http.Request) {
+	h.ctx = req.Context()
+}

pkg/apiserver/endpoints/request/accept.go

@@ -0,0 +1,22 @@
+package request
+
+import (
+	"context"
+)
+
+type acceptHeaderKey struct{}
+
+// WithAcceptHeader adds the accept header to the supplied context.
+func WithAcceptHeader(ctx context.Context, acceptHeader string) context.Context {
+	// only add the accept header to ctx if it is not empty
+	if acceptHeader == "" {
+		return ctx
+	}
+	return context.WithValue(ctx, acceptHeaderKey{}, acceptHeader)
+}
+
+// AcceptHeaderFrom returns the accept header from the supplied context and a boolean indicating if the value was present.
+func AcceptHeaderFrom(ctx context.Context) (string, bool) {
+	acceptHeader, ok := ctx.Value(acceptHeaderKey{}).(string)
+	return acceptHeader, ok
+}

pkg/apiserver/endpoints/request/accept_test.go

@@ -0,0 +1,26 @@
+package request
+
+import (
+	"context"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestAcceptHeader(t *testing.T) {
+	ctx := context.Background()
+
+	t.Run("should not set ctx for empty header", func(t *testing.T) {
+		out := WithAcceptHeader(ctx, "")
+		acceptHeader, ok := AcceptHeaderFrom(out)
+		require.False(t, ok)
+		require.Empty(t, acceptHeader)
+	})
+
+	t.Run("should add header to ctx", func(t *testing.T) {
+		out := WithAcceptHeader(ctx, "application/json")
+		acceptHeader, ok := AcceptHeaderFrom(out)
+		require.True(t, ok)
+		require.Equal(t, "application/json", acceptHeader)
+	})
+}