Merge pull request #393 from orange-guo/main

enhancement(link_local_dns.go): avoid occur runtime panic when the nameservers are empty.

helper/link_local_dns.go

@@ -32,6 +32,12 @@ type LinkLocalDNS struct {
 }
 
 func (l LinkLocalDNS) Execute() (map[string]string, error) {
+	// In some cases, the nameservers are empty.
+	// For example, when using the host network, and host '/etc/resolv.conf' file content is empty.
+	if len(l.Config.Servers) == 0 {
+		return nil, nil
+	}
+
 	if !net.ParseIP(l.Config.Servers[0]).IsLinkLocalUnicast() {
 		return nil, nil
 	}

helper/link_local_dns_test.go

@@ -59,6 +59,15 @@ func testLinkLocalDNS(t *testing.T, context spec.G, it spec.S) {
 		Expect(ioutil.ReadFile(path)).To(Equal([]byte("test")))
 	})
 
+	it("do nothing if no nameservers", func() {
+		config := &ddns.ClientConfig{Servers: []string{}}
+
+		l := helper.LinkLocalDNS{Config: config}
+
+		Expect(l.Execute()).To(BeNil())
+		Expect(ioutil.ReadFile(path)).To(Equal([]byte(`test`)))
+	})
+
 	it("returns an error if $JAVA_SECURITY_PROPERTIES is not set", func() {
 		config := &ddns.ClientConfig{Servers: []string{"169.254.0.1"}}
 		l := helper.LinkLocalDNS{Config: config}