Cloudera Manager is an end-to-end application used for managing CDH clusters. When a CDH service (such as Impala, Spark, etc.) is added to the cluster, Cloudera Manager configures cluster hosts with one or more functions, called roles.
In a Cloudera Manager cluster, a gateway role is one that designates that a host should receive client configuration for a CDH service even though the host does not have any role instances for that service running on it. Gateway roles provide the configuration required for clients that want to access the CDH cluster. Hosts that are designated with gateway roles for CDH services are referred to as gateway hosts.
Cloudera Machine Learning runs on one or more dedicated gateway hosts on CDH clusters. Each of these hosts has the Cloudera Manager Agent installed on them. The Cloudera Management Agent ensures that Cloudera Machine Learning has the libraries and configuration necessary to securely access the CDH cluster.
Cloudera Machine Learning does not support running any other services on these gateway hosts. Each gateway host must be dedicated solely to Cloudera Machine Learning. This is because user workloads require dedicated CPU and memory, which might conflict with other services running on these hosts. Any workloads that you run on Cloudera Machine Learning hosts will have immediate secure access to the CDH cluster.
From the assigned gateway hosts, one will serve as the master host while others will serve as worker hosts.