Always Access active NameNode from outside

[#1]

We have an application outside CDH that need to write to HDFS. So it need to know the active namenode URL. 

We have a nameserveiceHA configured within CDH cluster but we are looking to access it from utside CDH as well. 

We are using CDH 5.9

[#2]

One quick solution is to add application host to cluster and give (only) HDFS Gateway role to it.
Then you can use NameNode Nameservice name as uri e.g. hdfs://nameservice1/.

This could be done with CM.

https://www.cloudera.com/documentation/enterprise/5-9-x/topics/cm_mc_adding_hosts.html
https://www.cloudera.com/documentation/enterprise/5-9-x/topics/cm_mc_managing_roles.html


Pros:
- Can manage configuration centrally.

Cons:
- Host goes under CM management i.e. get monitored by agent, be capable of getting assigned other roles and so on.
- Files are distributed e.g. under /opt/cloudera which consume disk space (take log space into consideration also).
- Some ports - 9000 and 9001 are used by agent.
These might cross administrative boundary that please carefully consider and make a plan beforehand.