Adding a new node to a Live cluster is almost similar to installing a new HDP cluster with ambari. To add a new host you must enable passwordless ssh from the ambari-server to the new host.
Pre-requisites
1. Make sure you can do a passwordless ssh from ambari-server to the new host to be added.
2. You have generated the private ssh key in the ambari-server (this is already done when we first installed the HDP).
3. Add the new hosts FQDN in the /etc/hosts file of all the nodes in the cluster including the new host and ambari server.
# cat /etc/hosts
192.168.1.6 ambari-server.localdomain ambari-server
192.168.1.2 nn1.localdomain nn1
192.168.1.7 nn2.localdomain nn2
192.168.1.3 dn1.localdomain dn1
192.168.1.4 dn2.localdomain dn2
192.168.1.5 dn3.localdomain dn3
4. Disable iptables/firewalld in the new host. For my CentOS 7 hosts, I need to stop and disable firewalld.
# systemctl disable firewalld # systemctl stop firewalld
Install Options
On “Install Options” page, provide the new host FQDN and the SSH private key from the ambari server.
Confirm Hosts
If everything is configured correctly the installation will start and you can view the logs of installation by clicking on the status.
The installation will take some time to completed. You may get some warnings with the prechecks done on the new hosts like firewalld is enabled etc. You can clear these warnings and re-run the prechecks.
Assign Slaves and Clients
We would not assign any role to the new hosts to keep things simple. If asked in the exam you can tick the appropriate role and proceed.
Review
On the next page, you can review the configuration and begine the installation.
Install, Start and Test
The installer will start installing the necessary packages and start the components. The installer will also test the new components if they are working correctly.
Post completion of the installation, you may have to start a few services manually if they fail to start automatically.
Summary
Review the summary page for the installed components.
You can verify the new host added in the hosts tab in ambari.
As you can see we do not have much running on this host at the moment. But we can always enable new services/components later on.
