Parsing `X-Envoy-Peer-Metadata`

peer-metadata-parsing.md

Parsing the x-envoy-peer-metadata field.

eg, in istio outbound

{
  "args": {}, 
  "headers": {
    "Accept-Encoding": "gzip", 
    "Host": "httpbin.org", 
    "User-Agent": "Go-http-client/1.1", 
    "X-Envoy-Attempt-Count": "1", 
    "X-Envoy-Decorator-Operation": "httpbin.org:443/*", 
    "X-Envoy-Peer-Metadata": "ChoKCkNMVVNURVJfSUQSDBoKS3ViZXJuZXRlcwp1CgZMQUJFTFMSayppCgwKA2FwcBIFGgNtZHMKKAofc2VydmljZS5pc3Rpby5pby9jYW5vbmljYWwtbmFtZRIFGgNtZHMKLwojc2VydmljZS5pc3Rpby5pby9jYW5vbmljYWwtcmV2aXNpb24SCBoGbGF0ZXN0Ch4KBE5BTUUSFhoUbWRzLTZjOGY3ZGM4YjktczJibDYKFQoJTkFNRVNQQUNFEggaBm1kcy1ucwpGCgVPV05FUhI9GjtrdWJlcm5ldGVzOi8vYXBpcy9hcHBzL3YxL25hbWVzcGFjZXMvbWRzLW5zL2RlcGxveW1lbnRzL21kcwoWCg1XT1JLTE9BRF9OQU1FEgUaA21kcw==", 
    "X-Envoy-Peer-Metadata-Id": "sidecar~10.244.0.32~mds-6c8f7dc8b9-s2bl6.mds-ns~mds-ns.svc.cluster.local"
  }, 
  "origin": "100.15.177.221", 
  "url": "https://httpbin.org/get"
}

to parse the data above:

$ go run main.go 
map[CLUSTER_ID:Kubernetes LABELS:map[app:mds service.istio.io/canonical-name:mds service.istio.io/canonical-revision:latest] NAME:mds-6c8f7dc8b9-s2bl6 NAMESPACE:mds-ns OWNER:kubernetes://apis/apps/v1/namespaces/mds-ns/deployments/mds WORKLOAD_NAME:mds]
a == mds-6c8f7dc8b9-s2bl6
2024-11-10T14:26:10.125198Z	info	{
	"CLUSTER_ID": "Kubernetes",
	"LABELS": {
		"app": "mds",
		"service.istio.io/canonical-name": "mds",
		"service.istio.io/canonical-revision": "latest"
	},
	"NAME": "mds-6c8f7dc8b9-s2bl6",
	"NAMESPACE": "mds-ns",
	"OWNER": "kubernetes://apis/apps/v1/namespaces/mds-ns/deployments/mds",
	"WORKLOAD_NAME": "mds"
}
2024-11-10T14:26:10.125371Z	info	Name mds-6c8f7dc8b9-s2bl6
2024-11-10T14:26:10.125380Z	info	CLUSTER_ID Kubernetes
2024-11-10T14:26:10.125384Z	info	NameSpace mds-ns
2024-11-10T14:26:10.125388Z	info	OWNER kubernetes://apis/apps/v1/namespaces/mds-ns/deployments/mds
2024-11-10T14:26:10.125393Z	info	WORKLOAD_NAME mds
2024-11-10T14:26:10.125397Z	info	app: mds
2024-11-10T14:26:10.125400Z	info	service.istio.io/canonical-name: mds
2024-11-10T14:26:10.125404Z	info	service.istio.io/canonical-revision: latest

---

• main.go:

package main

import (
	"bytes"
	"encoding/base64"
	"encoding/json"
	"fmt"
	"log"

	"google.golang.org/protobuf/proto"

	"google.golang.org/protobuf/types/known/structpb"

	model "istio.io/istio/pkg/model"
)

var ()

const ()

type configFile struct {
	Keys map[string]string `json:"keys"`
}

func main() {

	ua := "ChoKCkNMVVNURVJfSUQSDBoKS3ViZXJuZXRlcwp1CgZMQUJFTFMSayppCgwKA2FwcBIFGgNtZHMKKAofc2VydmljZS5pc3Rpby5pby9jYW5vbmljYWwtbmFtZRIFGgNtZHMKLwojc2VydmljZS5pc3Rpby5pby9jYW5vbmljYWwtcmV2aXNpb24SCBoGbGF0ZXN0Ch4KBE5BTUUSFhoUbWRzLTZjOGY3ZGM4YjktczJibDYKFQoJTkFNRVNQQUNFEggaBm1kcy1ucwpGCgVPV05FUhI9GjtrdWJlcm5ldGVzOi8vYXBpcy9hcHBzL3YxL25hbWVzcGFjZXMvbWRzLW5zL2RlcGxveW1lbnRzL21kcwoWCg1XT1JLTE9BRF9OQU1FEgUaA21kcw=="

	decodedpeer, err := base64.StdEncoding.DecodeString(ua)
	if err != nil {
		log.Printf("Error %s", err)
		return
	}

	var s structpb.Struct
	err = proto.Unmarshal([]byte(decodedpeer), &s)
	if err != nil {
		log.Printf("Error %s", err)
		return
	}
	j, err := s.MarshalJSON()
	if err != nil {
		log.Printf("Error %s", err)
		return
	}

	var anyJson map[string]interface{}

	err = json.Unmarshal(j, &anyJson)
	if err != nil {
		log.Printf("Error %s", err)
		return
	}
	fmt.Printf("%s\n", anyJson)
	fmt.Println("a ==", anyJson["NAME"].(string))

	var prettyJSON bytes.Buffer
	error := json.Indent(&prettyJSON, j, "", "\t")
	if error != nil {
		log.Printf("Error %s", err)
		return
	}

	log.Println("\n", string(prettyJSON.Bytes()))

	// https://github.com/istio/istio/blob/aa93c1f0e74bd9d87bd4a89816d48dc70f867d45/pkg/model/proxy.go#L156C6-L156C27

	g := &model.BootstrapNodeMetadata{}

	err = json.Unmarshal(j, g)
	if err != nil {
		fmt.Println("Error:", err)
		return
	}

	log.Printf("Name %s", g.InstanceName)
	log.Printf("CLUSTER_ID %s", g.ClusterID)
	log.Printf("NameSpace %s", g.Namespace)
	log.Printf("OWNER %s", g.Owner)
	log.Printf("WORKLOAD_NAME %s", g.WorkloadName)
	for i, l := range g.Labels {
		log.Printf("%s: %s\n", i, l)
	}
}