feat: Add record truncation and improve logging

.dockerignore

@@ -6,3 +6,5 @@ README.md
 .git/
 .gitignore
 .vscode/
+manifests/
+skaffold.yaml

Dockerfile

@@ -1,17 +1,18 @@
-FROM --platform=$BUILDPLATFORM golang:1.16 as build
-LABEL maintainer="Blake Covarrubias <[email protected]>" \
-      org.opencontainers.image.authors="Blake Covarrubias <[email protected]>" \
-      org.opencontainers.image.description="Advertises records for Kubernetes resources over multicast DNS." \
-      org.opencontainers.image.licenses="Apache-2.0" \
-      org.opencontainers.image.source="[email protected]:blake/external-mdns" \
-      org.opencontainers.image.title="external-mdns" \
-      org.opencontainers.image.url="https://github.com/blake/external-mdns"
+FROM --platform=$BUILDPLATFORM golang:1.23 as build
+LABEL \
+    maintainer="Blake Covarrubias <[email protected]>" \
+    org.opencontainers.image.authors="Blake Covarrubias <[email protected]>" \
+    org.opencontainers.image.description="Advertises records for Kubernetes resources over multicast DNS." \
+    org.opencontainers.image.licenses="Apache-2.0" \
+    org.opencontainers.image.source="[email protected]:blake/external-mdns" \
+    org.opencontainers.image.title="external-mdns" \
+    org.opencontainers.image.url="https://github.com/blake/external-mdns"
 
 ARG TARGETOS
 ARG TARGETARCH
 ARG TARGETVARIANT
 
-ADD . /go/src/github.com/blake/external-mdns
+ADD . /go/src/github.com/blake/external-mdns/
 WORKDIR /go/src/github.com/blake/external-mdns
 
 RUN mkdir -p /release/etc &&\

main.go

@@ -122,6 +122,21 @@ func reverseAddress(addr string) (arpa string, err error) {
 	return string(buf), nil
 }
 
+var (
+	master           		= ""
+	namespace        		= ""
+	defaultNamespace 		= "default"
+	withoutNamespace 		= false
+	test             		= flag.Bool("test", false, "testing mode, no connection to k8s")
+	sourceFlag       		k8sSource
+	kubeconfig       		string
+	exposeIPv4       		= true
+	exposeIPv6       		= false
+	publishInternal  		= flag.Bool("publish-internal-services", false, "Publish DNS records for ClusterIP services (optional)")
+	recordTTL        		= 120
+	truncateLongRecords 		bool
+)
+
 func constructRecords(r resource.Resource) []string {
 	var records []string
 
@@ -135,29 +150,31 @@ func constructRecords(r resource.Resource) []string {
 
 		var recordType string
 		if ip.To4() != nil {
-			if exposeIPv4 == false {
+			if !exposeIPv4 {
 				continue
 			}
 			recordType = "A"
 		} else {
-			if exposeIPv6 == false {
+			if !exposeIPv6 {
 				continue
 			}
 			recordType = "AAAA"
 		}
 
 		// Publish records resources as <name>.<namespace>.local
 		// Ensure corresponding PTR records map to this hostname
-		records = append(records, fmt.Sprintf("%s.%s.local. %d IN %s %s", r.Name, r.Namespace, recordTTL, recordType, ip))
+		records = append(records, validatedRecord(r.Name, r.Namespace, recordTTL, recordType, ip, truncateLongRecords))
+
 		if reverseIP != "" {
-			records = append(records, fmt.Sprintf("%s %d IN PTR %s.%s.local.", reverseIP, recordTTL, r.Name, r.Namespace))
+			records = append(records, validatedPTRRecord(reverseIP, recordTTL, r.Name, r.Namespace, truncateLongRecords))
 		}
 
 		// Publish records resources as <name>-<namespace>.local
 		// Because Windows does not support subdomains resolution via mDNS and uses regular DNS query instead.
-		records = append(records, fmt.Sprintf("%s-%s.local. %d IN %s %s", r.Name, r.Namespace, recordTTL, recordType, ip))
+		records = append(records, validatedRecord(fmt.Sprintf("%s-%s", r.Name, r.Namespace), "", recordTTL, recordType, ip, truncateLongRecords))
+
 		if reverseIP != "" {
-			records = append(records, fmt.Sprintf("%s %d IN PTR %s-%s.local.", reverseIP, recordTTL, r.Name, r.Namespace))
+			records = append(records, validatedPTRRecord(reverseIP, recordTTL, fmt.Sprintf("%s-%s", r.Name, r.Namespace), "", truncateLongRecords))
 		}
 
 		// Publish services without the name in the namespace if any of the following
@@ -166,9 +183,10 @@ func constructRecords(r resource.Resource) []string {
 		// 2. The -without-namespace flag is equal to true
 		// 3. The record to be published is from an Ingress with a defined hostname
 		if r.Namespace == defaultNamespace || withoutNamespace || r.SourceType == "ingress" {
-			records = append(records, fmt.Sprintf("%s.local. %d IN %s %s", r.Name, recordTTL, recordType, ip))
+			records = append(records, validatedRecord(r.Name, "", recordTTL, recordType, ip, truncateLongRecords))
+
 			if reverseIP != "" {
-				records = append(records, fmt.Sprintf("%s %d IN PTR %s.local.", reverseIP, recordTTL, r.Name))
+				records = append(records, validatedPTRRecord(reverseIP, recordTTL, r.Name, "", truncateLongRecords))
 			}
 		}
 	}
@@ -178,30 +196,16 @@ func constructRecords(r resource.Resource) []string {
 
 func publishRecord(rr string) {
 	if err := mdns.Publish(rr); err != nil {
-		log.Fatalf(`Unable to publish record "%s": %v`, rr, err)
+		log.Fatalf(`🔥 Failed to publish record "%s": %v`, rr, err)
 	}
 }
 
 func unpublishRecord(rr string) {
 	if err := mdns.UnPublish(rr); err != nil {
-		log.Fatalf(`Unable to publish record "%s": %v`, rr, err)
+		log.Fatalf(`🔥 Failed to unpublish record "%s": %v`, rr, err)
 	}
 }
 
-var (
-	master           = ""
-	namespace        = ""
-	defaultNamespace = "default"
-	withoutNamespace = false
-	test             = flag.Bool("test", false, "testing mode, no connection to k8s")
-	sourceFlag       k8sSource
-	kubeconfig       string
-	exposeIPv4       = true
-	exposeIPv6       = false
-	publishInternal  = flag.Bool("publish-internal-services", false, "Publish DNS records for ClusterIP services (optional)")
-	recordTTL        = 120
-)
-
 func main() {
 
 	// Kubernetes options
@@ -216,6 +220,7 @@ func main() {
 	flag.BoolVar(&exposeIPv4, "expose-ipv4", lookupEnvOrBool("EXTERNAL_MDNS_EXPOSE_IPV4", exposeIPv4), "Publish A DNS entry (default: true)")
 	flag.BoolVar(&exposeIPv6, "expose-ipv6", lookupEnvOrBool("EXTERNAL_MDNS_EXPOSE_IPV6", exposeIPv6), "Publish AAAA DNS entry (default: false)")
 	flag.IntVar(&recordTTL, "record-ttl", lookupEnvOrInt("EXTERNAL_MDNS_RECORD_TTL", recordTTL), "DNS record time-to-live")
+	flag.BoolVar(&truncateLongRecords, "truncate-long-records", lookupEnvOrBool("EXTERNAL_MDNS_TRUNCATE_LONG_RECORDS", false), "Truncate long record names using SHA-256 hash (default: false)")
 
 	flag.Parse()
 
@@ -228,16 +233,16 @@ func main() {
 
 	// No sources provided.
 	if len(sourceFlag) == 0 {
-		fmt.Println("Specify at least once source to sync records from.")
+		log.Println("❌ Error: No sources specified. Please specify at least one source to sync records from")
 		os.Exit(1)
 	}
 
 	// Print parsed configuration
-	log.Printf("app.config %v\n", getConfig(flag.CommandLine))
+	log.Printf("🚀 Starting external-mdns with configuration:\n%v\n", getConfig(flag.CommandLine))
 
 	k8sClient, err := newK8sClient()
 	if err != nil {
-		log.Fatalln("Failed to create Kubernetes client:", err)
+		log.Fatalf("🔥 Failed to create Kubernetes client: %v", err)
 	}
 
 	notifyMdns := make(chan resource.Resource)
@@ -261,17 +266,20 @@ func main() {
 		select {
 		case advertiseResource := <-notifyMdns:
 			for _, record := range constructRecords(advertiseResource) {
+				if record == "" {
+					continue
+				}
 				switch advertiseResource.Action {
 				case resource.Added:
-					log.Printf("Added %s\n", record)
+					log.Printf("➕ Publishing new DNS record: %s\n", record)
 					publishRecord(record)
 				case resource.Deleted:
-					log.Printf("Remove %s\n", record)
+					log.Printf("➖ Removing DNS record: %s\n", record)
 					unpublishRecord(record)
 				}
 			}
 		case <-stopper:
-			fmt.Println("Stopping program")
+			log.Println("🛑 Stopping external-mdns")
 		}
 	}
 }

manifests/k8s-cluster-role-binding.yaml

@@ -0,0 +1,12 @@
+apiVersion: rbac.authorization.k8s.io/v1
+kind: ClusterRoleBinding
+metadata:
+  name: external-mdns-viewer
+roleRef:
+  apiGroup: rbac.authorization.k8s.io
+  kind: ClusterRole
+  name: external-mdns
+subjects:
+- kind: ServiceAccount
+  name: external-mdns
+  namespace: default # Assicurati che il namespace sia corretto

manifests/k8s-cluster-role.yaml

@@ -0,0 +1,11 @@
+apiVersion: rbac.authorization.k8s.io/v1
+kind: ClusterRole
+metadata:
+  name: external-mdns
+rules:
+- apiGroups: [""]
+  resources: ["services"]
+  verbs: ["list", "watch"]
+- apiGroups: ["networking.k8s.io"]
+  resources: ["ingresses"]
+  verbs: ["list", "watch"]

manifests/k8s-deployment-template.yaml

@@ -0,0 +1,41 @@
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: external-mdns
+spec:
+  strategy:
+    type: Recreate
+  selector:
+    matchLabels:
+      app: external-mdns
+  template:
+    metadata:
+      labels:
+        app: external-mdns
+    spec:
+      securityContext:
+        runAsUser: 65534
+        runAsGroup: 65534
+        runAsNonRoot: true
+      hostNetwork: true
+      serviceAccountName: external-mdns # Assicurati che questo service account esista
+      containers:
+      - name: external-mdns
+        securityContext:
+          readOnlyRootFilesystem: true
+          allowPrivilegeEscalation: false
+          capabilities:
+            drop: ["ALL"]
+        image: external-mdns # Skaffold sostituirà questo con l'immagine buildata
+        args:
+        - -source=ingress
+        - -source=service
+        - -truncate-long-records=true # Abilita il troncamento dei record
+        - -publish-internal-services=true
+        env:
+          - name: EXTERNAL_MDNS_NAMESPACE
+            value: "" # Modifica se vuoi limitare a un namespace specifico, lascialo vuoto per tutti i namespace
+          - name: EXTERNAL_MDNS_DEFAULT_NAMESPACE
+            value: "default" # Modifica se necessario
+          - name: EXTERNAL_MDNS_KUBECONFIG
+            value: "" # Generalmente non necessario in Minikube

manifests/k8s-service-account.yaml

@@ -0,0 +1,4 @@
+apiVersion: v1
+kind: ServiceAccount
+metadata:
+  name: external-mdns

record.go

@@ -0,0 +1,75 @@
+package main
+
+import (
+	"crypto/sha256"
+	"encoding/hex"
+	"fmt"
+	"log"
+	"net"
+)
+
+func validatedFullName(name, namespace string, recordType string, truncate bool) string {
+	// Determiniamo il tipo di record per il log
+	recordKind := recordType
+	if recordType == "" {
+		recordKind = "PTR"
+	}
+
+	// Verifica la lunghezza di ogni componente del nome
+	components := []string{name}
+	if namespace != "" {
+		components = append(components, namespace)
+	}
+
+	// Verifica ogni componente
+	for _, component := range components {
+		if len(component) > 63 {
+			if truncate {
+				// Se il componente è troppo lungo, lo tronchiamo
+				hasher := sha256.New()
+				hasher.Write([]byte(component))
+				hash := hex.EncodeToString(hasher.Sum(nil))
+				shortComponent := component[:51]
+				truncatedComponent := fmt.Sprintf("%s-%s", shortComponent, hash[:8])
+				log.Printf("✂️  DNS label '%s' exceeds length limit (63 chars) for %s record\n"+
+					"                      └─ Truncated to: '%s'\n",
+					component, recordKind, truncatedComponent)
+
+				// Sostituisci il componente originale con quello troncato
+				if component == name {
+					name = truncatedComponent
+				} else {
+					namespace = truncatedComponent
+				}
+			} else {
+				log.Printf("❌ DNS label '%s' exceeds length limit (63 chars) for %s record\n"+
+					"                      └─ Record will not be published\n",
+					component, recordKind)
+				return ""
+			}
+		}
+	}
+
+	// Costruisci il nome completo
+	if namespace != "" {
+		return fmt.Sprintf("%s.%s", name, namespace)
+	}
+	return name
+}
+
+func validatedRecord(name, namespace string, ttl int, recordType string, ip net.IP, truncate bool) string {
+	fullname := validatedFullName(name, namespace, recordType, truncate)
+	if fullname == "" {
+		return ""
+	}
+	return fmt.Sprintf("%s.local. %d IN %s %s", fullname, ttl, recordType, ip)
+}
+
+func validatedPTRRecord(reverseIP string, ttl int, name, namespace string, truncate bool) string {
+	// Passiamo una stringa vuota come recordType, verrà interpretata come PTR
+	fullname := validatedFullName(name, namespace, "", truncate)
+	if fullname == "" {
+		return ""
+	}
+	return fmt.Sprintf("%s %d IN PTR %s.local.", reverseIP, ttl, fullname)
+}

skaffold.yaml

@@ -0,0 +1,18 @@
+apiVersion: skaffold/v4beta8
+kind: Config
+build:
+  artifacts:
+  - image: external-mdns
+    context: .
+    docker:
+      dockerfile: Dockerfile
+  local:
+    push: false
+deploy:
+  kubectl: {}
+manifests:
+  rawYaml:
+      - manifests/k8s-deployment-template.yaml
+      - manifests/k8s-service-account.yaml
+      - manifests/k8s-cluster-role.yaml
+      - manifests/k8s-cluster-role-binding.yaml