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Instances Introduction

An instance in OpenStack is a virtual machine that runs in the cloud. These instances are created from images and configured using flavors, which define their hardware characteristics such as CPU, RAM, and storage. Instances can be managed by users and administrators to perform various tasks, such as starting, stopping, rebooting, migrating, and creating snapshots.

Concepts​

Images​

Images in OpenStack are disk templates that contain an operating system and optionally pre-installed applications. These images are used to create virtual machine instances. The OpenStack service responsible for managing images is called Glance.

Flavors​

A flavor in OpenStack defines the hardware characteristics of an instance, such as the amount of CPU, RAM, and storage. Flavors allow users to select the appropriate hardware configuration for their needs when launching an instance.

Security Group​

Security groups in OpenStack act as a virtual firewall for instances, controlling incoming and outgoing network traffic. Users can define rules to allow or deny traffic based on IP addresses, ports, and protocols.

Network​

Networking in OpenStack is managed through the Neutron service. This service allows users to create and manage virtual networks, subnets, and routers. Neutron provides network connectivity to instances and enables the configuration of advanced network policies.

Volumes​

Volumes are the Block Storage devices that you attach to instances to enable persistent storage. Users can attach a volume to a running instance or detach a volume and attach it to another instance at any time. Is managed with Glance.

List resources names and ids​

Here are the commands to list the resources that OpenStack instances should have defined:

$ openstack image list
$ openstack flavor list
$ openstack security group list
$ openstack network list
$ openstack volume list