feat: add support for hgctl gateway-config to retrieve higress gateway config (#274)

Signed-off-by: bitliu <bitliu@tencent.com>

pkg/cmd/hgctl/configRetriever.go

@@ -0,0 +1,151 @@
+// Copyright (c) 2022 Alibaba Group Holding Ltd.
+//
+// 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 hgctl
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+
+	"github.com/alibaba/higress/pkg/cmd/hgctl/kubernetes"
+	"github.com/alibaba/higress/pkg/cmd/options"
+	"k8s.io/apimachinery/pkg/types"
+	"sigs.k8s.io/yaml"
+)
+
+var (
+	output       string
+	podName      string
+	podNamespace string
+)
+
+const (
+	adminPort     = 15000
+	containerName = "envoy"
+)
+
+func retrieveConfigDump(args []string, includeEds bool) ([]byte, error) {
+	if len(args) != 0 {
+		podName = args[0]
+	}
+
+	if podNamespace == "" {
+		return nil, fmt.Errorf("pod namespace is required")
+	}
+
+	if podName == "" || len(args) == 0 {
+		c, err := kubernetes.NewCLIClient(options.DefaultConfigFlags.ToRawKubeConfigLoader())
+		if err != nil {
+			return nil, fmt.Errorf("failed to build kubernetes client: %w", err)
+		}
+		podList, err := c.PodsForSelector(podNamespace, "app=higress-gateway")
+		if err != nil {
+			return nil, err
+		}
+		if len(podList.Items) == 0 {
+			return nil, fmt.Errorf("higress gateway pod is not existed in namespace %s", podNamespace)
+		}
+
+		podName = podList.Items[0].GetName()
+	}
+
+	fw, err := portForwarder(types.NamespacedName{
+		Namespace: podNamespace,
+		Name:      podName,
+	})
+	if err != nil {
+		return nil, err
+	}
+	if err := fw.Start(); err != nil {
+		return nil, err
+	}
+	defer fw.Stop()
+
+	configDump, err := fetchGatewayConfig(fw, includeEds)
+	if err != nil {
+		return nil, err
+	}
+
+	return configDump, nil
+}
+
+func portForwarder(nn types.NamespacedName) (kubernetes.PortForwarder, error) {
+	c, err := kubernetes.NewCLIClient(options.DefaultConfigFlags.ToRawKubeConfigLoader())
+	if err != nil {
+		return nil, fmt.Errorf("build CLI client fail: %w", err)
+	}
+
+	pod, err := c.Pod(nn)
+	if err != nil {
+		return nil, fmt.Errorf("get pod %s fail: %w", nn, err)
+	}
+	if pod.Status.Phase != "Running" {
+		return nil, fmt.Errorf("pod %s is not running", nn)
+	}
+
+	fw, err := kubernetes.NewLocalPortForwarder(c, nn, 0, adminPort)
+	if err != nil {
+		return nil, err
+	}
+
+	return fw, nil
+}
+
+func formatGatewayConfig(configDump any, output string) ([]byte, error) {
+	out, err := json.MarshalIndent(configDump, "", "  ")
+	if err != nil {
+		return nil, err
+	}
+
+	if output == "yaml" {
+		out, err = yaml.JSONToYAML(out)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	return out, nil
+}
+
+func fetchGatewayConfig(fw kubernetes.PortForwarder, includeEds bool) ([]byte, error) {
+	out, err := configDumpRequest(fw.Address(), includeEds)
+	if err != nil {
+		return nil, err
+	}
+
+	return out, nil
+}
+
+func configDumpRequest(address string, includeEds bool) ([]byte, error) {
+	url := fmt.Sprintf("http://%s/config_dump", address)
+	if includeEds {
+		url = fmt.Sprintf("%s?include_eds", url)
+	}
+	req, err := http.NewRequest("GET", url, nil)
+	if err != nil {
+		return nil, err
+	}
+
+	resp, err := http.DefaultClient.Do(req)
+	if err != nil {
+		return nil, err
+	}
+	defer func() {
+		_ = resp.Body.Close()
+	}()
+
+	return io.ReadAll(resp.Body)
+}