Configure a Compute node

After you configure the Compute service on the controller node, you must configure another system as a Compute node. The Compute node receives requests from the controller node and hosts virtual machine instances. You can run all services on a single node, but the examples in this guide use separate systems. This makes it easy to scale horizontally by adding additional Compute nodes following the instructions in this section.

The Compute service relies on a hypervisor to run virtual machine instances. OpenStack can use various hypervisors, but this guide uses KVM.

Configure the system. Use the instructions in Chapter 2, Basic operating system configuration, but note the following differences from the controller node:
- Use different IP addresses when you configure eth0. This guide uses 192.168.0.11 for the internal network. Do not configure eth1 with a static IP address. The networking component of OpenStack assigns and configures an IP address.
- Set the host name to compute1. To verify, use the uname -n parameter. Ensure that the IP addresses and host names for both nodes are listed in the /etc/hosts file on each system.
- Synchronize from the controller node. Follow the instructions in the section called “Network Time Protocol (NTP)”.
- Install the MySQL client libraries. You do not need to install the MySQL database server or start the MySQL service.
- Enable the OpenStack packages for the distribution that you are using. See the section called “OpenStack packages”.
After you configure the operating system, install the appropriate packages for the Compute service.
Run this command:
```
# apt-get install nova-compute-kvm python-guestfs
```
When prompted to create a supermin appliance, respond yes.

Due to this bug. To make the current kernel readable, run:

# dpkg-statoverride  --update --add root root 0644 /boot/vmlinuz-$(uname -r)

To also enable this override for all future kernel updates, create the file /etc/kernel/postinst.d/statoverride containing:

#!/bin/sh
version="$1"
# passing the kernel version is required
[ -z "${version}" ] && exit 0
dpkg-statoverride --update --add root root 0644 /boot/vmlinuz-${version}

Remember to make the file executable:

# chmod +x /etc/kernel/postinst.d/statoverride

Edit the /etc/nova/nova.conf configuration file and add these lines to the appropriate sections:

...
[DEFAULT]
...
auth_strategy=keystone
...
[database]
# The SQLAlchemy connection string used to connect to the database
connection = mysql://nova:NOVA_DBPASS@controller/nova

Configure the Compute Service to use the RabbitMQ message broker by setting these configuration keys in the [DEFAULT] configuration group of the /etc/nova/nova.conf file:
```
rpc_backend = nova.rpc.impl_kombu
rabbit_host = controller
rabbit_password = RABBIT_PASS
```

Configure Compute to provide remote console access to instances.

Edit /etc/nova/nova.conf and add the following keys under the [DEFAULT] section:

[DEFAULT]
...
my_ip=192.168.0.11
vnc_enabled=True
vncserver_listen=0.0.0.0
vncserver_proxyclient_address=192.168.0.11
novncproxy_base_url=http://controller:6080/vnc_auto.html

Specify the host that runs the Image Service. Edit /etc/nova/nova.conf file and add these lines to the [DEFAULT] section:
```
[DEFAULT]
...
glance_host=controller
```
Edit the /etc/nova/api-paste.ini file to add the credentials to the [filter:authtoken] section:
Use of .ini files
Files with the extension .ini sometimes need to be edited during initial setup. However, they should not be used for general configuration tasks.
```
[filter:authtoken]
paste.filter_factory = keystoneclient.middleware.auth_token:filter_factory
auth_host = controller
auth_port = 35357
auth_protocol = http
admin_tenant_name = service
admin_user = nova
admin_password = NOVA_PASS
```
Restart the Compute service.
```
# service nova-compute restart
```
Remove the SQLite database created by the packages:
```
# rm /var/lib/nova/nova.sqlite
```

	Use of .ini files
Files with the extension `.ini` sometimes need to be edited during initial setup. However, they should not be used for general configuration tasks.

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