Install and configure a compute node¶

This section describes how to install and configure the Compute service on a compute node. The service supports several hypervisors to deploy instances or VMs. For simplicity, this configuration uses the QEMU hypervisor with the KVM extension on compute nodes that support hardware acceleration for virtual machines. On legacy hardware, this configuration uses the generic QEMU hypervisor. You can follow these instructions with minor modifications to horizontally scale your environment with additional compute nodes.

Note

This section assumes that you are following the instructions in this guide step-by-step to configure the first compute node. If you want to configure additional compute nodes, prepare them in a similar fashion to the first compute node in the example architectures section. Each additional compute node requires a unique IP address.

Install and configure components¶

Note

Default configuration files vary by distribution. You might need to add these sections and options rather than modifying existing sections and options. Also, an ellipsis (...) in the configuration snippets indicates potential default configuration options that you should retain.

Install the packages:

# yum install openstack-nova-compute sysfsutils

Edit the /etc/nova/nova.conf file and complete the following actions:
- In the [DEFAULT] and [oslo_messaging_rabbit] sections, configure RabbitMQ message queue access:
```
[DEFAULT]
...
rpc_backend = rabbit

[oslo_messaging_rabbit]
...
rabbit_host = controller
rabbit_userid = openstack
rabbit_password = RABBIT_PASS
```
  Replace RABBIT_PASS with the password you chose for the openstack account in RabbitMQ.
- In the [DEFAULT] and [keystone_authtoken] sections, configure Identity service access:
```
[DEFAULT]
...
auth_strategy = keystone

[keystone_authtoken]
...
auth_uri = http://controller:5000
auth_url = http://controller:35357
auth_plugin = password
project_domain_id = default
user_domain_id = default
project_name = service
username = nova
password = NOVA_PASS
```
  Replace NOVA_PASS with the password you chose for the nova user in the Identity service.
  
  Note
  
  Comment out or remove any other options in the [keystone_authtoken] section.
- In the [DEFAULT] section, configure the my_ip option:
```
[DEFAULT]
...
my_ip = MANAGEMENT_INTERFACE_IP_ADDRESS
```
  Replace MANAGEMENT_INTERFACE_IP_ADDRESS with the IP address of the management network interface on your compute node, typically 10.0.0.31 for the first node in the example architecture.
- In the [DEFAULT] section, enable support for the Networking service:
```
[DEFAULT]
...
network_api_class = nova.network.neutronv2.api.API
security_group_api = neutron
linuxnet_interface_driver = nova.network.linux_net.NeutronLinuxBridgeInterfaceDriver
firewall_driver = nova.virt.firewall.NoopFirewallDriver
```
  Note
  
  By default, Compute uses an internal firewall service. Since Networking includes a firewall service, you must disable the Compute firewall service by using the nova.virt.firewall.NoopFirewallDriver firewall driver.
- In the [vnc] section, enable and configure remote console access:
```
[vnc]
...
enabled = True
vncserver_listen = 0.0.0.0
vncserver_proxyclient_address = $my_ip
novncproxy_base_url = http://controller:6080/vnc_auto.html
```
  The server component listens on all IP addresses and the proxy component only listens on the management interface IP address of the compute node. The base URL indicates the location where you can use a web browser to access remote consoles of instances on this compute node.
  
  Note
  
  If the web browser to access remote consoles resides on a host that cannot resolve the controller hostname, you must replace controller with the management interface IP address of the controller node.
- In the [glance] section, configure the location of the Image service:
```
[glance]
...
host = controller
```
- In the [oslo_concurrency] section, configure the lock path:
```
[oslo_concurrency]
...
lock_path = /var/lib/nova/tmp
```
- (Optional) To assist with troubleshooting, enable verbose logging in the [DEFAULT] section:
```
[DEFAULT]
...
verbose = True
```

Finalize installation¶

Determine whether your compute node supports hardware acceleration for virtual machines:
```
$ egrep -c '(vmx|svm)' /proc/cpuinfo
```
If this command returns a value of one or greater, your compute node supports hardware acceleration which typically requires no additional configuration.

If this command returns a value of zero, your compute node does not support hardware acceleration and you must configure libvirt to use QEMU instead of KVM.
- Edit the [libvirt] section in the /etc/nova/nova.conf file as follows:
```
[libvirt]
...
virt_type = qemu
```

Start the Compute service including its dependencies and configure them to start automatically when the system boots:

# systemctl enable libvirtd.service openstack-nova-compute.service
# systemctl start libvirtd.service openstack-nova-compute.service