Fix the issue that DNS record doesn't get updated when user change environment name

Environment name was initialized when external dns starts up. So it will not get updated if user change the env name after  dns starting.

rancher/rancher#10077

Author: loganhz

metadata/metadata.go

@@ -61,8 +61,12 @@ func (m *MetadataClient) GetVersion() (string, error) {
 }
 
 func (m *MetadataClient) GetMetadataDnsRecords() (map[string]utils.MetadataDnsRecord, error) {
+	err := m.updateEnvironmentName()
+	if err != nil {
+		return nil, err
+	}
 	dnsEntries := make(map[string]utils.MetadataDnsRecord)
-	err := m.getContainersDnsRecords(dnsEntries)
+	err = m.getContainersDnsRecords(dnsEntries)
 	if err != nil {
 		return dnsEntries, err
 	}
@@ -171,6 +175,18 @@ func (m *MetadataClient) getContainersDnsRecords(dnsEntries map[string]utils.Met
 	return nil
 }
 
+func (m *MetadataClient) updateEnvironmentName() error {
+	envName, _, err := getEnvironment(m.MetadataClient)
+	if err != nil {
+		logrus.Errorf("Failed to get environment info: %v", err)
+		return err
+	} else {
+		m.EnvironmentName = envName
+	}
+
+	return nil
+}
+
 func addToDnsEntries(fqdn, ip, service, stack string, dnsEntries map[string]utils.MetadataDnsRecord) {
 	var records []string
 	if _, ok := dnsEntries[fqdn]; !ok {