egctl: support config envoy-stats command (#1892)

* feature: added envoy stats config

Signed-off-by: tanujd11 <dwiveditanuj41@gmail.com>

* lint fix and review comments

Signed-off-by: tanujd11 <dwiveditanuj41@gmail.com>

* update portForwarder function

Signed-off-by: tanujd11 <dwiveditanuj41@gmail.com>

* review comments

Signed-off-by: tanujd11 <dwiveditanuj41@gmail.com>

* make linter happy

Signed-off-by: tanujd11 <dwiveditanuj41@gmail.com>

* nit fix

Signed-off-by: tanujd11 <dwiveditanuj41@gmail.com>

---------

Signed-off-by: tanujd11 <dwiveditanuj41@gmail.com>
Co-authored-by: zirain <zirain2009@gmail.com>

internal/cmd/egctl/envoy_stats.go

@@ -0,0 +1,200 @@
+// 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 egctl
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"sync"
+
+	"github.com/spf13/cobra"
+	"github.com/tetratelabs/multierror"
+	"k8s.io/apimachinery/pkg/types"
+	"sigs.k8s.io/yaml"
+
+	"github.com/envoyproxy/gateway/internal/kubernetes"
+)
+
+const (
+	summaryOutput    = "statsd"
+	prometheusOutput = "prom"
+)
+
+var (
+	statsType, outputFormat string
+)
+
+func newEnvoyStatsCmd() *cobra.Command {
+	var podName, podNamespace string
+
+	statsConfigCmd := &cobra.Command{
+		Use:   "envoy-proxy <name> -n <namespace>",
+		Short: "Retrieves Envoy metrics in the specified pod",
+		Long:  `Retrieve Envoy emitted metrics for the specified pod.`,
+		Example: `  # Retrieve Envoy emitted metrics for the specified pod.
+  egctl experimental stats <pod-name> -n <namespace>
+
+  # Retrieve Envoy server metrics in prometheus format
+  egctl experimental stats envoy-proxy <pod-name> -n <namespace> --output prom
+
+  # Retrieve Envoy cluster metrics
+  egctl experimental stats  envoy-proxy <pod-name> -n <namespace> --type clusters
+`,
+		Aliases: []string{"ep"},
+		Args: func(cmd *cobra.Command, args []string) error {
+			if len(args) != 1 && len(labelSelectors) == 0 {
+				cmd.Println(cmd.UsageString())
+				return fmt.Errorf("stats requires pod name or label selector")
+			}
+			return nil
+		},
+		RunE: func(c *cobra.Command, args []string) error {
+			stats := map[string]string{}
+			kubeClient, err := getCLIClient()
+			if err != nil {
+				return err
+			}
+			if len(args) != 0 {
+				podName = args[0]
+			}
+			pods, err := fetchRunningEnvoyPods(kubeClient, types.NamespacedName{Namespace: podNamespace, Name: podName}, labelSelectors, allNamespaces)
+			if err != nil {
+				return err
+			}
+			var errs error
+			var wg sync.WaitGroup
+			switch statsType {
+			case "", "server":
+				wg.Add(len(pods))
+				for _, pod := range pods {
+					go func(pod types.NamespacedName) {
+						stats[pod.Namespace+"/"+pod.Name], err = setupEnvoyServerStatsConfig(kubeClient, pod.Name, pod.Namespace, outputFormat)
+						if err != nil {
+							errs = multierror.Append(errs, err)
+						}
+						wg.Done()
+					}(pod)
+				}
+
+				wg.Wait()
+			case "cluster", "clusters":
+				wg.Add(len(pods))
+				for _, pod := range pods {
+					go func(pod types.NamespacedName) {
+						stats[pod.Namespace+"/"+pod.Name], err = setupEnvoyClusterStatsConfig(kubeClient, pod.Name, pod.Namespace, outputFormat)
+						if err != nil {
+							errs = multierror.Append(errs, err)
+						}
+						wg.Done()
+					}(pod)
+				}
+				wg.Wait()
+			default:
+				return fmt.Errorf("unknown stats type %s", statsType)
+			}
+
+			if errs != nil {
+				return errs
+			}
+
+			switch outputFormat {
+			// convert the json output to yaml
+			case yamlOutput:
+				var out []byte
+				statsBytes, err := json.Marshal(stats)
+				if err != nil {
+					return err
+				}
+				if out, err = yaml.JSONToYAML(statsBytes); err != nil {
+					return err
+				}
+				_, _ = fmt.Fprint(c.OutOrStdout(), string(out))
+			default:
+				for namespacedName, stat := range stats {
+					_, _ = fmt.Fprint(c.OutOrStdout(), namespacedName+":\n")
+					_, _ = fmt.Fprint(c.OutOrStdout(), stat)
+				}
+			}
+
+			return nil
+		},
+	}
+	statsConfigCmd.PersistentFlags().StringVarP(&outputFormat, "output", "o", summaryOutput, "Output format: one of json|yaml|prom")
+	statsConfigCmd.PersistentFlags().StringVarP(&statsType, "type", "t", "server", "Where to grab the stats: one of server|clusters")
+	statsConfigCmd.PersistentFlags().StringArrayVarP(&labelSelectors, "labels", "l", nil, "Labels to select the envoy proxy pod.")
+	statsConfigCmd.PersistentFlags().StringVarP(&podNamespace, "namespace", "n", "envoy-gateway-system", "Namespace where envoy proxy pod are installed.")
+
+	return statsConfigCmd
+}
+
+func setupEnvoyServerStatsConfig(kubeClient kubernetes.CLIClient, podName, podNamespace string, outputFormat string) (string, error) {
+	path := "stats"
+	if outputFormat == jsonOutput || outputFormat == yamlOutput {
+		// for yaml output we will convert the json to yaml when printed
+		path += "?format=json"
+	} else {
+		path += "/prometheus"
+	}
+
+	fw, err := portForwarder(kubeClient, types.NamespacedName{Namespace: podNamespace, Name: podName})
+	if err != nil {
+		return "", fmt.Errorf("failed to initialize pod-forwarding for %s/%s: %v", podNamespace, podName, err)
+	}
+	err = fw.Start()
+	if err != nil {
+		return "", fmt.Errorf("failed to start port forwarding for pod %s/%s: %v", podNamespace, podName, err)
+	}
+	defer fw.Stop()
+
+	result, err := statsRequest(fw.Address(), path)
+	if err != nil {
+		return "", fmt.Errorf("failed to get stats on envoy for pod %s/%s: %v", podNamespace, podName, err)
+	}
+	return string(result), nil
+}
+
+func setupEnvoyClusterStatsConfig(kubeClient kubernetes.CLIClient, podName, podNamespace string, outputFormat string) (string, error) {
+	path := "clusters"
+	if outputFormat == jsonOutput || outputFormat == yamlOutput {
+		// for yaml output we will convert the json to yaml when printed
+		path += "?format=json"
+	}
+	fw, err := portForwarder(kubeClient, types.NamespacedName{Namespace: podNamespace, Name: podName})
+	if err != nil {
+		return "", fmt.Errorf("failed to initialize pod-forwarding for %s/%s: %v", podNamespace, podName, err)
+	}
+	err = fw.Start()
+	if err != nil {
+		return "", fmt.Errorf("failed to start port forwarding for pod %s/%s: %v", podNamespace, podName, err)
+	}
+	defer fw.Stop()
+
+	result, err := statsRequest(fw.Address(), path)
+	if err != nil {
+		return "", fmt.Errorf("failed to get stats on envoy for pod %s/%s: %v", podNamespace, podName, err)
+	}
+	return string(result), nil
+}
+
+func statsRequest(address string, path string) ([]byte, error) {
+	url := fmt.Sprintf("http://%s/%s", address, path)
+	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)
+}

internal/cmd/egctl/experimental.go

@@ -23,6 +23,7 @@ func newExperimentalCommand() *cobra.Command {
 	}
 
 	experimentalCommand.AddCommand(NewTranslateCommand())
+	experimentalCommand.AddCommand(statsCommand())
 
 	return experimentalCommand
 }

internal/cmd/egctl/stats.go

@@ -0,0 +1,21 @@
+// 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 egctl
+
+import (
+	"github.com/spf13/cobra"
+)
+
+func statsCommand() *cobra.Command {
+	c := &cobra.Command{
+		Use:  "stats",
+		Long: "Retrieve stats from envoy proxy.",
+	}
+
+	c.AddCommand(newEnvoyStatsCmd())
+
+	return c
+}