I faced similar issue, but REST api thru -   http://localhost:8080/api/v1/cluster/[cluster_name]/services/KERBEROS  was not available, and kerberos remove was giving error - "The 'krb5-conf' configuration is not available" in ambari-server.log   We had Ambari 2.7.5.0. In that version clusterconfigmapping is not present, we had to do below procedure:   In ambari db -  psql -U ambari -d ambari (default password: bigdata) ambari=> select config_id, selected, create_timestamp from clusterconfig where type_name in ('kerberos-env', 'krb5-conf'); config_id | selected | create_timestamp -----------+----------+------------------ 352 | 0 | 1589796215822 452 | 0 | 1589800820822 << Select the record with latest timestamp 353 | 0 | 1589796215857 453 | 0 | 1589800820858 <<Select the record with latest timestamp (4 rows) ambari=> update clusterconfig set selected=1 where config_id=452; UPDATE 1 ambari=> update clusterconfig set selected=1 where config_id=453; UPDATE 1 ambari=> update clusterconfig set selected=1 where config_id=452; update clusterconfig set selected=1 where config_id=453;   * Still the kerberos REST api was not been shown. * Remove the kerberos * Add kerberos back ... View more

@Elvis Zhang You can avoid Ambari UI to ask password for kadmin. You can store that kadmin credential to ambari store. https://community.hortonworks.com/articles/42927/adding-kdc-administrator-credentials-to-the-ambari.html curl -H "X-Requested-By:ambari" -u admin:admin -X PUT -d '{ "Credential" : { "principal" : "admin/admin@EXAMPLE.COM", "key" : "pwd$hwx", "type" : "persisted" } }' http://ambari.example.com:8080/api/v1/clusters/c1/credentials/kdc.admin.credential . Above will require a keystore setup and then "[2] Encrypt passwords stored in ambari.properties file." on ambari-server setup-security wizard. Using this way you can avoid entering the kadmin credentials everytime on ambari. ... View more

yes i checked "/etc/krb5.conf", again ,nothing wrong ,from error text ,it means "*.keytabs" file used old "EXAMPLE.COM", I don't know how to update or rebuild the keytabs? ... View more

OK i fix it . My OS is 'Centos 7.1', i alos used (Centos 6.*) service iptables stop So i change is with systemctl stop firewalld Every thing is ok Now , Thanks for Jay's help again. ... View more