The aim of the compute service is to launch, monitor, and manage the cloud compute infrastructure—in this case, VM. Nova is the OpenStack project that provides a way to provision, launch, and manage VM. You can create a VM using Nova. In conjunction with another project called Ironic, Nova can also be used to launch a bare-metal server. Nova has a limited capability for running system containers, and it provides its services by running a set of daemons on top of existing Linux servers. Nova allows users to create , scale , reboot , and delete instances. They can do this via the UI or by using the CLI.

Nova works in conjunction with other services. These services are needed for Nova to have its basic functions:

• Keystone: This is needed to provide the identity and authentication of users using Nova.
• Glance: This is needed to obtain the images that the virtual instances use to be launched.
• Neutron: This is needed to build the network to which the instances will connect to once they start.

Nova also interacts with Cinder to obtain block storage volumes and attaches these volumes to the virtual instances.

The end users can interact with Nova by either using the tools or by using the APIs directly. The tools that can be used include the following:

• Horizon, the WebUI provided by OpenStack.
• OpenStack CLI, called the OpenStack client, which can be used for Nova, as well as for other OpenStack services.
• Nova Client, which can be used for some very advanced features. While Nova Client is supported, OpenStack recommends using the OpenStack CLI whenever possible.

The Nova project exposes all the end-user features via REST APIs. So, if the end user wants to build complex logic or an automation, they can do this by using the APIs directly, or by using an API via an SDK. The following diagram gives us an idea of how Nova interacts with other OpenStack projects, such as Keystone, Neutron, and Glance: