The OpenStack system has several components that are installed separately but which can work together depending on your cloud needs. Key components include: OpenStack Compute, OpenStack Object Storage, and OpenStack Image Store. There are basic configuration decisions to make, and the OpenStack Install Guide covers a few different architectures for certain use cases.

Configuring your Compute installation involves many configuration files: the nova.conf file, the api-paste.ini file, and related Image and Identity management configuration files. This section contains the basics for a simple multi-node installation, but Compute can be configured many ways. You can find networking options and hypervisor options described in separate chapters.

The configuration file nova.conf is installed in /etc/nova by default. A default set of options are already configured in nova.conf when you install manually. Create a nova group, so you can set permissions on the configuration file: $ sudo addgroup nova The nova.conf file should have its owner set to root:nova, and mode set to 0640, since the file could contain your MySQL server’s username and password. You also want to ensure that the nova user belongs to the nova group. $ sudo usermod -g nova nova $ chown -R username:nova /etc/nova $ chmod 640 /etc/nova/nova.conf

You can use nova.conf file to configure where Compute logs events, the level of logging, and log formats. To customize log formats for OpenStack Compute, use these configuration option settings.

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There are different methods of authentication for the OpenStack Compute project, including no authentication. The preferred system is the OpenStack Identity Service, code-named Keystone. To customize authorization settings for Compute, see these configuration settings in nova.conf. To customize certificate authority settings for Compute, see these configuration settings in nova.conf. To customize Compute and the Identity service to use LDAP as a backend, refer to these configuration settings in nova.conf.

Resize (or Server resize) is the ability to change the flavor of a server, thus allowing it to upscale or downscale according to user needs. For this feature to work properly, some underlying virt layers may need further configuration; this section describes the required configuration steps for each hypervisor layer provided by OpenStack.

To get resize to work with XenServer (and XCP), please refer to the Dom0 Modifications for Resize/Migration Support section in the OpenStack Compute Administration Guide.