sort HTTP filters

Signed-off-by: huabing zhao <[email protected]>

internal/xds/translator/httpfilters.go

@@ -0,0 +1,101 @@
+// Copyright Envoy Gateway Authors
+// SPDX-License-Identifier: Apache-2.0
+// The full text of the Apache license is available in the LICENSE file at
+// the root of the repo.
+
+package translator
+
+import (
+	"sort"
+
+	hcmv3 "github.com/envoyproxy/go-control-plane/envoy/extensions/filters/network/http_connection_manager/v3"
+	"github.com/envoyproxy/go-control-plane/pkg/wellknown"
+
+	"github.com/envoyproxy/gateway/internal/ir"
+	xdsfilters "github.com/envoyproxy/gateway/internal/xds/filters"
+)
+
+type OrderedHTTPFilter struct {
+	filter *hcmv3.HttpFilter
+	order  int
+}
+
+type OrderedHTTPFilters []*OrderedHTTPFilter
+
+func newOrderedHTTPFilter(filter *hcmv3.HttpFilter) *OrderedHTTPFilter {
+	order := 50
+
+	// Set a rational order for all the filters.
+	switch filter.Name {
+	case wellknown.CORS:
+		order = 1
+	case jwtAuthenFilter:
+		order = 2
+	case wellknown.HTTPRateLimit:
+		order = 3
+	case wellknown.Router:
+		order = 100
+	}
+
+	return &OrderedHTTPFilter{
+		filter: filter,
+		order:  order,
+	}
+}
+
+// sort.Interface implementation.
+func (o OrderedHTTPFilters) Len() int {
+	return len(o)
+}
+
+func (o OrderedHTTPFilters) Less(i, j int) bool {
+	return o[i].order < o[j].order
+}
+
+func (o OrderedHTTPFilters) Swap(i, j int) {
+	o[i], o[j] = o[j], o[i]
+}
+
+// sortHTTPFilters sorts the HTTP filters in the correct order.
+// This is needed because the order of the filters is important.
+// For example, the cors filter must be before the router filter.
+// The router filter must be the last one.
+func sortHTTPFilters(filters []*hcmv3.HttpFilter) []*hcmv3.HttpFilter {
+	orderedFilters := make(OrderedHTTPFilters, len(filters))
+	for i := 0; i < len(filters); i++ {
+		orderedFilters[i] = newOrderedHTTPFilter(filters[i])
+	}
+	sort.Sort(orderedFilters)
+
+	for i := 0; i < len(filters); i++ {
+		filters[i] = orderedFilters[i].filter
+	}
+	return filters
+}
+
+// patchHCMWithFilters builds and appends HTTP Filters to the HTTP connection
+// manager.
+func (t *Translator) patchHCMWithFilters(mgr *hcmv3.HttpConnectionManager, irListener *ir.HTTPListener) error {
+	// The order of filter patching is not relevant here.
+	// All the filters will be sorted in correct order after the patching is done.
+	// TODO: Make this a generic interface for all API Gateway features.
+	//       https://github.com/envoyproxy/gateway/issues/882
+	t.patchHCMWithRateLimit(mgr, irListener)
+
+	// Add the jwt authn filter, if needed.
+	if err := patchHCMWithJwtAuthnFilter(mgr, irListener); err != nil {
+		return err
+	}
+
+	// Add the cors filter, if needed
+	if err := patchHCMWithCorsFilter(mgr, irListener); err != nil {
+		return err
+	}
+
+	// Add the router filter
+	mgr.HttpFilters = append(mgr.HttpFilters, xdsfilters.HTTPRouter)
+
+	// Sort the filters in the correct order.
+	mgr.HttpFilters = sortHTTPFilters(mgr.HttpFilters)
+	return nil
+}

internal/xds/translator/httpfilters_test.go

@@ -0,0 +1,49 @@
+// Copyright Envoy Gateway Authors
+// SPDX-License-Identifier: Apache-2.0
+// The full text of the Apache license is available in the LICENSE file at
+// the root of the repo.
+
+package translator
+
+import (
+	"testing"
+
+	hcmv3 "github.com/envoyproxy/go-control-plane/envoy/extensions/filters/network/http_connection_manager/v3"
+	"github.com/envoyproxy/go-control-plane/pkg/wellknown"
+	"github.com/stretchr/testify/assert"
+)
+
+func Test_sortHTTPFilters(t *testing.T) {
+	tests := []struct {
+		name    string
+		filters []*hcmv3.HttpFilter
+		want    []*hcmv3.HttpFilter
+	}{
+		{
+			name: "sort filters",
+			filters: []*hcmv3.HttpFilter{
+				httpFilterForTest(wellknown.Router),
+				httpFilterForTest(wellknown.CORS),
+				httpFilterForTest(jwtAuthenFilter),
+				httpFilterForTest(wellknown.HTTPRateLimit),
+			},
+			want: []*hcmv3.HttpFilter{
+				httpFilterForTest(wellknown.CORS),
+				httpFilterForTest(jwtAuthenFilter),
+				httpFilterForTest(wellknown.HTTPRateLimit),
+				httpFilterForTest(wellknown.Router),
+			},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			assert.Equalf(t, tt.want, sortHTTPFilters(tt.filters), "sortHTTPFilters(%v)", tt.filters)
+		})
+	}
+}
+
+func httpFilterForTest(name string) *hcmv3.HttpFilter {
+	return &hcmv3.HttpFilter{
+		Name: name,
+	}
+}

internal/xds/translator/listener.go

@@ -134,22 +134,12 @@ func (t *Translator) addXdsHTTPFilterChain(xdsListener *listenerv3.Listener, irL
 		}
 	}
 
-	// TODO: Make this a generic interface for all API Gateway features.
-	//       https://github.com/envoyproxy/gateway/issues/882
-	t.patchHCMWithRateLimit(mgr, irListener)
-
-	// Add the jwt authn filter, if needed.
-	if err := patchHCMWithJwtAuthnFilter(mgr, irListener); err != nil {
-		return err
-	}
-
-	// Add the cors filter, if needed
-	if err := patchHCMWithCorsFilter(mgr, irListener); err != nil {
+	// Add the HTTP filters to the HCM, the filters have been sorted in the
+	// correct order.
+	if err := t.patchHCMWithFilters(mgr, irListener); err != nil {
 		return err
 	}
 
-	// Make sure the router filter is the last one.
-	mgr.HttpFilters = append(mgr.HttpFilters, xdsfilters.HTTPRouter)
 	mgrAny, err := protocov.ToAnyWithError(mgr)
 	if err != nil {
 		return err