Chapter 8. Adding Hosts to an Existing Cluster

Ensure you have the latest installer and playbooks by updating the atomic-openshift-utils package:

# yum update atomic-openshift-utils

Run the installer with the scaleup subcommand in interactive or unattended mode:

# atomic-openshift-installer [-u] [-c </path/to/file>] scaleup

The installer detects your current environment and allows you to add additional nodes:

*** Installation Summary ***

Hosts:
- 100.100.1.1
  - OpenShift master
  - OpenShift node
  - Etcd (Embedded)
  - Storage

Total OpenShift masters: 1
Total OpenShift nodes: 1


---

We have detected this previously installed OpenShift environment.

This tool will guide you through the process of adding additional
nodes to your cluster.

Are you ready to continue? [y/N]:

Choose (y) and follow the on-screen instructions to complete your desired task.

Ensure you have the latest playbooks by updating the atomic-openshift-utils package:

# yum update atomic-openshift-utils

Edit your /etc/ansible/hosts file and add new_<host_type> to the [OSEv3:children] section:

For example, to add a new node host, add new_nodes:

[OSEv3:children]
masters
nodes
new_nodes

To add new master hosts, add new_masters.

Create a [new_<host_type>] section much like an existing section, specifying host information for any new hosts you want to add. For example, when adding a new node:

[nodes]
master[1:3].example.com
node1.example.com openshift_node_labels="{'region': 'primary', 'zone': 'east'}"
node2.example.com openshift_node_labels="{'region': 'primary', 'zone': 'west'}"
infra-node1.example.com openshift_node_labels="{'region': 'infra', 'zone': 'default'}"
infra-node2.example.com openshift_node_labels="{'region': 'infra', 'zone': 'default'}"

[new_nodes]
node3.example.com openshift_node_labels="{'region': 'primary', 'zone': 'west'}"

See Configuring Host Variables for more options.

When adding new masters, hosts added to the [new_masters] section must also be added to the [new_nodes] section. This ensures the new master host is part of the OpenShift SDN.

[masters]
master[1:2].example.com

[new_masters]
master3.example.com

[nodes]
master[1:2].example.com
node1.example.com openshift_node_labels="{'region': 'primary', 'zone': 'east'}"
node2.example.com openshift_node_labels="{'region': 'primary', 'zone': 'west'}"
infra-node1.example.com openshift_node_labels="{'region': 'infra', 'zone': 'default'}"
infra-node2.example.com openshift_node_labels="{'region': 'infra', 'zone': 'default'}"

[new_nodes]
master3.example.com

Masters are also automatically marked as unschedulable for pod placement by the installer.

Run the scaleup.yml playbook. If your inventory file is located somewhere other than the default of /etc/ansible/hosts, specify the location with the -i option.

For additional nodes:

# ansible-playbook [-i /path/to/file] \
    /usr/share/ansible/openshift-ansible/playbooks/byo/openshift-node/scaleup.yml

For additional masters:

# ansible-playbook [-i /path/to/file] \
    /usr/share/ansible/openshift-ansible/playbooks/byo/openshift-master/scaleup.yml

Finally, move any hosts you had defined in the [new_<host_type>] section into their appropriate section (but leave the [new_<host_type>] section definition itself in place) so that subsequent runs using this inventory file are aware of the nodes but do not handle them as new nodes. For example, when adding new nodes:

[nodes]
master[1:3].example.com
node1.example.com openshift_node_labels="{'region': 'primary', 'zone': 'east'}"
node2.example.com openshift_node_labels="{'region': 'primary', 'zone': 'west'}"
node3.example.com openshift_node_labels="{'region': 'primary', 'zone': 'west'}"
infra-node1.example.com openshift_node_labels="{'region': 'infra', 'zone': 'default'}"
infra-node2.example.com openshift_node_labels="{'region': 'infra', 'zone': 'default'}"

[new_nodes]