Shulou(Shulou.com)06/01 Report--

Compute Service Nova is the core service of OpenStack, which is responsible for maintaining and managing computing resources in cloud environment.

OpenStack as the cloud operating system of IaaS, virtual machine lifecycle management is realized through Nova.

As you can see in the figure above, Nova is at the center of the Openstak architecture, and other components support Nova:

Glance provides p_w_picpath for VM

Cinder and Swift provide block storage and object storage for VM respectively

Neutron provides network connectivity for VM

The Nova architecture is as follows

The architecture of Nova is complex and contains many components.

These components run as subservices (background deamon processes) and can be divided into the following categories:

API

Nova-api

Receive and respond to customer API calls. Amazon EC2 API is supported in addition to providing OpenStack's own API,nova-api. That is, if customers used to use Amazon EC2 and developed tools to manage virtual machines with EC2's API, then if they want to switch to OpenStack now, these tools can be seamlessly migrated to OpenStack because nova-api is EC2 API-compliant and does not need to be modified.

Compute Core

Nova-scheduler

Virtual machine scheduling service, which is responsible for deciding which computing node to run the virtual machine on

Nova-compute

Manage the core service of virtual machine, and realize the life cycle management of virtual machine by calling Hypervisor API.

Hypervisor

The virtual management program running on the computing node, and the virtual machine manages the lowest-level program. Different virtualization technologies provide their own Hypervisor. The commonly used Hypervisor are KVM,Xen, VMWare, etc.

Nova-conductor

Nova-compute often needs to update the database, such as the status of the virtual machine. For security and scalability reasons, nova-compute does not access the database directly, but delegates this task to nova-conductor, which we will discuss in more detail later.

Console Interface

Nova-console

Users can access the console of the virtual machine in many ways: nova-novncproxy, VNC access nova-spicehtml5proxy based on Web browser, SPICE access nova-x***vncproxy based on HTML5 browser, and VNC access based on Java client.

Nova-consoleauth

Responsible for accessing the virtual machine console, please provide Token authentication

Nova-cert

Provide x509 certificate support

Database

Nova will have some data that needs to be stored in the database, usually using MySQL. The database is installed on the control node. Nova uses a database named "nova".

Message Queue

We learned earlier that Nova contains a large number of sub-services, which need to coordinate and communicate with each other. In order to decouple each sub-service, Nova acts as the information transfer station of the sub-service through Message Queue. So we see on the architecture diagram that there is no direct connection between sub-services, they are all connected through Message Queue.

OpenStack defaults to using RabbitMQ as the Message Queue. MQ is the core basic component of OpenStack, which we will cover in more detail later.

In the next section, we discuss how these Nova components work together.

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