CentOS 7 firewall issue.

[andrew-ge-wu]

On centos 7 minimum, firewall are by default blocking external access.
Those are the commands I followed to open port 8080
[root@localhost ~]# firewall-cmd --get-active-zones
public
interfaces: enp0s3
[root@localhost ~]#
[root@localhost ~]# firewall-cmd --zone=public --add-port=8080/tcp --permanent
success
[root@localhost ~]# firewall-cmd --reload
success

After install Ambari, you will probably need to open more ports since there will be a list of applications installed. for example hdfs hive spark zk etc.