This article assumes that, you have a cluster with more than one node(which is a requirement for enabling HA on Atlas). Also make sure that atlas is up and running on that cluster. Please refer to this documentation link for deploying cluster with Atlas enabled.
Prerequisites for High Availability feature in Atlas
The following prerequisites must be met for setting up the High Availability feature.
Ensure that you install Apache Zookeeper on a cluster of machines (a minimum of 3 servers is recommended for production).
Select 2 or more physical machines to run the Atlas Web Service instances on. These machines define what we refer to as a 'server ensemble' for Atlas.
Step1: Verify from Ambari UI that Atlas is up and running..
Step2: Stop Atlas using Ambari
Step3: Navigate to host page in Ambari where Atlas service is not installed and add one more atlas service.
Step4: If Infra solr client is not installed on the host where we are trying to install another instance of Atlas, then Ambari would display this pop up window.
Add Infra solr client instance on the same host
Step5: After successfully adding Infra solr client, add Atlas server instance by following Step3.
Step6: Start the Atlas service now
Step7: Verify from ambari UI that both the atlas services should be up and running.
Step8: Check which instance of Atlas is Active and which one is passive..
HTTP get request on one of the Atlas instances showing its status as "Active"
HTTP get request on one of the Atlas instances showing its status as "Passive"
Step9: Now Atlas is running in HA mode(Active-Passive mode). With this, you should be able to access Atlas UI(this can be pulled from Ambari quick links).