Automatic Domain Resolution and Certificate Management for Kubernetes Ingress

Deployment

Please ensure that the following components are deployed:

cert-manager: Installation - cert-manager Documentation

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kubectl apply -f https://github.com/cert-manager/cert-manager/releases/download/v1.15.3/cert-manager.yaml

cert-manager-webhook-dnspod: imroc/cert-manager-webhook-dnspod: cert-manager webhook resolver for DNSPod (github.com)

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kubectl apply -f https://raw.githubusercontent.com/imroc/cert-manager-webhook-dnspod/master/bundle.yaml

Modify the deployment file ingress-dnspod-solver.yaml as follows:

ingress-dnspod-solver.yaml

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apiVersion: v1
kind: ServiceAccount
metadata:
  name: ingress-dnspod-solver
  namespace: cert-manager
  labels:
    app: ingress-dnspod-solver

---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  name: ingress-dnspod-solver
rules:
  - apiGroups: [ "networking.k8s.io" ]
    resources: [ "ingresses" ]
    verbs: [ "get", "list", "watch" ]

---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name: ingress-dnspod-solver
  labels:
    app: ingress-dnspod-solver
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: ingress-dnspod-solver
subjects:
  - apiGroup: ""
    kind: ServiceAccount
    name: ingress-dnspod-solver
    namespace: cert-manager

---
apiVersion: v1
kind: Secret
metadata:
  name: ingress-dnspod-solver
  namespace: cert-manager
type: Opaque
stringData:
  TENCENT_SECRET_KEY: "<secret_key>"  # Tencent Cloud API Secret Key

---
apiVersion: v1
kind: ConfigMap
metadata:
  name: ingress-dnspod-solver
  namespace: cert-manager
data:
  DOMAIN: "example.com"                # Domain name
  POLICY: "retain"                     # Monitoring handling policy: retain (keep records on resource update), update (update records on resource update)
  TENCENT_SECRET_ID: "<secret_id>"  # Tencent Cloud API Secret ID
  RECORD_VALUE: "<record_value>"          # DNS record value

---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: ingress-dnspod-solver
  namespace: cert-manager
  labels:
    app: ingress-dnspod-solver
spec:
  replicas: 1
  selector:
    matchLabels:
      app: ingress-dnspod-solver
  template:
    metadata:
      labels:
        app: ingress-dnspod-solver
    spec:
      serviceAccountName: ingress-dnspod-solver
      containers:
        - name: ingress-dnspod-solver
          image: harbor.example.com/devops/ingress-dnspod-solver:latest
          imagePullPolicy: IfNotPresent
          env:
            - name: DOMAIN
              valueFrom:
                configMapKeyRef:
                  name: ingress-dnspod-solver
                  key: DOMAIN
            - name: POLICY
              valueFrom:
                configMapKeyRef:
                  name: ingress-dnspod-solver
                  key: POLICY
            - name: TENCENT_SECRET_ID
              valueFrom:
                configMapKeyRef:
                  name: ingress-dnspod-solver
                  key: TENCENT_SECRET_ID
            - name: TENCENT_SECRET_KEY
              valueFrom:
                secretKeyRef:
                  name: ingress-dnspod-solver
                  key: TENCENT_SECRET_KEY
            - name: RECORD_VALUE
              valueFrom:
                configMapKeyRef:
                  name: ingress-dnspod-solver
                  key: RECORD_VALUE

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kubectl apply -f ingress-dnspod-solver.yaml

Source Code Analysis and Build

The source code is written in go and uses go mod to manage dependencies.

main.go

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package main

import (
	"fmt"
	"github.com/tencentcloud/tencentcloud-sdk-go/tencentcloud/common"
	"github.com/tencentcloud/tencentcloud-sdk-go/tencentcloud/common/profile"
	dnspod "github.com/tencentcloud/tencentcloud-sdk-go/tencentcloud/dnspod/v20210323"
	"go.uber.org/zap"
	networkingv1 "k8s.io/api/networking/v1"
	"k8s.io/client-go/informers"
	"k8s.io/client-go/kubernetes"
	"k8s.io/client-go/rest"
	"k8s.io/client-go/tools/cache"
	"k8s.io/client-go/tools/clientcmd"
	"os"
)

var (
	logger       *zap.Logger
	version      string
	policy       string
	domain       string
	secretId     string
	secretKey    string
	recordValue  string
	dnsPodClient *dnspod.Client
	clientSet    *kubernetes.Clientset
)

func initLogger() {
	logger, _ = zap.NewDevelopment()
	defer func(logger *zap.Logger) {
		err := logger.Sync()
		if err != nil {
			fmt.Println("Logger sync error: ", err)
		}
	}(logger)
}

func initCheck() {
	version = os.Getenv("VERSION")
	if version == "" {
		version = "2021-03-23"
	}
	policy = os.Getenv("POLICY")
	if policy == "" {
		policy = "retain"
	}
	domain = os.Getenv("DOMAIN")
	if domain == "" {
		logger.Error("Please set the environment variable `DOMAIN`")
		os.Exit(1)
	}
	secretId = os.Getenv("TENCENT_SECRET_ID")
	secretKey = os.Getenv("TENCENT_SECRET_KEY")
	if secretId == "" || secretKey == "" {
		logger.Error("Please set the environment variables `TENCENT_SECRET_ID` and `TENCENT_SECRET_KEY`")
		os.Exit(1)
	}
	recordValue = os.Getenv("RECORD_VALUE")
	if recordValue == "" {
		logger.Error("Please set the environment variable `RECORD_VALUE`")
		os.Exit(1)
	}

	logger.Info("---------------------------------")
	logger.Info("Version" + ": " + version)
	logger.Info("Policy" + ": " + policy)
	logger.Info("Domain" + ": " + domain)
	logger.Info("SecretId" + ": " + secretId)
	logger.Info("SecretKey: *****")
	logger.Info("RecordValue" + ": " + recordValue)
	logger.Info("---------------------------------")
}

func getRecordDict() map[string]uint64 {
	recordDict := make(map[string]uint64)
	request := dnspod.NewDescribeRecordListRequest()
	request.Domain = common.StringPtr(domain)
	request.RecordType = common.StringPtr("A")
	request.Offset = common.Uint64Ptr(0)
	request.Limit = common.Uint64Ptr(10)

	// Response corresponds to the DescribeRecordListResponse instance
	response, err := dnsPodClient.DescribeRecordList(request)
	if err != nil {
		logger.Panic(err.Error())
	}
	for i := 0; i < len(response.Response.RecordList); i++ {
		recordDict[*response.Response.RecordList[i].Name] = *response.Response.RecordList[i].RecordId
	}
	domainCount := *response.Response.RecordCountInfo.ListCount
	domainTotal := *response.Response.RecordCountInfo.TotalCount
	for domainCount < domainTotal {
		request.Offset = common.Uint64Ptr(domainCount)
		response, err = dnsPodClient.DescribeRecordList(request)
		if err != nil {
			logger.Panic(err.Error())
		}
		for i := 0; i < len(response.Response.RecordList); i++ {
			recordDict[*response.Response.RecordList[i].Name] = *response.Response.RecordList[i].RecordId
		}
		domainCount += *response.Response.RecordCountInfo.ListCount
	}

	logger.Info("RecordDict: ", zap.Any("RecordDict", recordDict))
	return recordDict
}

func createRecord(subDomain string) {
	request := dnspod.NewCreateRecordRequest()
	request.Domain = common.StringPtr(domain)
	request.SubDomain = common.StringPtr(subDomain)
	request.RecordType = common.StringPtr("A")
	request.RecordLine = common.StringPtr("默认")
	request.Value = common.StringPtr(recordValue)

	_, err := dnsPodClient.CreateRecord(request)
	if err != nil {
		logger.Panic(err.Error())
	}
}

func updateRecord(recordId uint64, subDomain string) {
	request := dnspod.NewModifyRecordRequest()
	request.Domain = common.StringPtr(domain)
	request.RecordId = common.Uint64Ptr(recordId)
	request.SubDomain = common.StringPtr(subDomain)
	request.RecordType = common.StringPtr("A")
	request.RecordLine = common.StringPtr("默认")
	request.Value = common.StringPtr(recordValue)

	_, err := dnsPodClient.ModifyRecord(request)
	if err != nil {
		logger.Panic(err.Error())
	}
}

func deleteRecord(recordId uint64) {
	request := dnspod.NewDeleteRecordRequest()
	request.Domain = common.StringPtr(domain)
	request.RecordId = common.Uint64Ptr(recordId)

	_, err := dnsPodClient.DeleteRecord(request)
	if err != nil {
		logger.Panic(err.Error())
	}
}

func addHandler(obj interface{}) {
	logger.Info("Detected Ingress Add event")
	recordDict := getRecordDict()
	addIngress := obj.(*networkingv1.Ingress)
	for i := 0; i < len(addIngress.Spec.Rules); i++ {
		customDomain := addIngress.Spec.Rules[i].Host
		// Check if customDomain ends with domain
		if customDomain[len(customDomain)-len(domain):] != domain {
			continue
		}
		subDomain := customDomain[:len(customDomain)-len(domain)-1]
		if _, ok := recordDict[subDomain]; !ok {
			createRecord(subDomain)
		} else {
			if policy == "update" {
				updateRecord(recordDict[subDomain], subDomain)
			}
		}
	}
}

func updateHandler(oldObj, newObj interface{}) {
	logger.Info("Detected Ingress Update event")
	recordDict := getRecordDict()
	newIngress := newObj.(*networkingv1.Ingress)
	for i := 0; i < len(newIngress.Spec.Rules); i++ {
		customDomain := newIngress.Spec.Rules[i].Host
		// Check if customDomain ends with domain
		if customDomain[len(customDomain)-len(domain):] != domain {
			continue
		}
		subDomain := customDomain[:len(customDomain)-len(domain)-1]
		if _, ok := recordDict[subDomain]; !ok {
			createRecord(subDomain)
		} else {
			updateRecord(recordDict[subDomain], subDomain)
		}
	}
}

func deleteHandler(obj interface{}) {
	logger.Info("Detected Ingress Delete event")
	recordDict := getRecordDict()
	deleteIngress := obj.(*networkingv1.Ingress)
	for i := 0; i < len(deleteIngress.Spec.Rules); i++ {
		customDomain := deleteIngress.Spec.Rules[i].Host
		// Check if customDomain ends with domain
		if customDomain[len(customDomain)-len(domain):] != domain {
			continue
		}
		subDomain := customDomain[:len(customDomain)-len(domain)-1]
		if _, ok := recordDict[subDomain]; ok {
			deleteRecord(recordDict[subDomain])
		}
	}
}

func k8sInformer() {
	// Create shared Informer factory
	factory := informers.NewSharedInformerFactory(clientSet, 0)

	// Get Ingress watcher Informer
	ingressInformer := factory.Networking().V1().Ingresses().Informer()

	// Add event handlers for Ingress resource changes
	_, err := ingressInformer.AddEventHandler(cache.ResourceEventHandlerFuncs{
		AddFunc:    addHandler,
		UpdateFunc: updateHandler,
		DeleteFunc: deleteHandler,
	})
	if err != nil {
		return
	}

	// Start informer and wait for cache sync
	stopCh := make(chan struct{})
	defer close(stopCh)
	factory.Start(stopCh)
	factory.WaitForCacheSync(stopCh)

	// Block to keep listening for events
	<-stopCh
}

func main() {
	// Initialization
	initLogger()
	initCheck()

	// Create DNSPod client
	credential := common.NewCredential(secretId, secretKey)
	cpf := profile.NewClientProfile()
	cpf.HttpProfile.Endpoint = "dnspod.tencentcloudapi.com"
	dnsPodClient, _ = dnspod.NewClient(credential, "", cpf)

	// Create Kubernetes client
	var config *rest.Config
	var err error
	// Check if running inside cluster
	if os.Getenv("KUBERNETES_SERVICE_HOST") != "" {
		config, err = rest.InClusterConfig()
		if err != nil {
			logger.Panic(err.Error())
		}
	} else {
		if _, err = os.Stat("./.kube/config"); os.IsNotExist(err) {
			logger.Panic("Please set the kubeconfig file")
		}
		config, err = clientcmd.BuildConfigFromFlags("", "./.kube/config")
	}
	clientSet, err = kubernetes.NewForConfig(config)
	if err != nil {
		logger.Panic(err.Error())
	}
	k8sInformer()
}

Dockerfile

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FROM golang:alpine AS builder
WORKDIR /app
COPY . .
RUN go mod download
RUN go build -o main .

FROM alpine:latest
WORKDIR /app
COPY --from=builder /app/main .
CMD ["./main"]

Build image

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docker build -t harbor.example.com/devops/ingress-dnspod-solver:latest .

Push image

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docker push harbor.example.com/devops/ingress-dnspod-solver:latest