OpenStack Question and Answers

What is OpenStack?

OpenStack is a set of software tools for building and managing cloud computing platforms for public and private clouds. Backed by some of the biggest companies in software development and hosting, as well as thousands of individual community members, many think that OpenStack is the future of cloud computing. OpenStack is managed by the OpenStack Foundation, a non-profit which oversees both development and community-building around the project.

Introduction to OpenStack

OpenStack lets users deploy virtual machines and other instances which handle different tasks for managing a cloud environment on the fly. It makes horizontal scaling easy, which means that tasks which benefit from running concurrently can easily serve more or less users on the fly by just spinning up more instances. For example, a mobile application which needs to communicate with a remote server might be able to divide the work of communicating with each user across many different instances, all communicating with one another but scaling quickly and easily as the application gains more users.

OpenStack is open source software, which means that anyone who chooses to can access the source code, make any changes or modifications they need, and freely share these changes back out to the community at large. It also means that OpenStack has the benefit of thousands of developers all over the world working in tandem to develop the strongest, most robust, and most secure product that they can.

How is OpenStack used in a cloud environment?

The cloud is all about providing computing for end users in a remote environment, where the actual software runs as a service on reliable and scalable servers rather than on each end users computer. Cloud computing can refer to a lot of different things, but typically the industry talks about running different items "as a service"—software, platforms, and infrastructure.

OpenStack falls into the category called Infrastructure as a Service (IaaS). Providing infrastructure means that OpenStack makes it easy for users to quickly add new instance, upon which other cloud components can run. Typically, the infrastructure then runs a "platform" upon which a developer can create software applications which are delivered to the end users.

What are the components of OpenStack?

OpenStack is made up of many different moving parts. Because of its open nature, anyone can add additional components to OpenStack to help it to meet their needs. But the OpenStack community has collaboratively identified nine key components that are a part of the "core" of OpenStack, which are distributed as a part of any OpenStack system and officially maintained by the OpenStack community.

·         Nova is the primary computing engine behind OpenStack. It is a "fabric controller," which is used for deploying and managing large numbers of virtual machines and other instances to handle computing tasks.

·         Swift is a storage system for objects and files. Rather than the traditional idea of a referring to files by their location on a disk drive, developers can instead refer to a unique identifier referring to the file or piece of information and let OpenStack decide where to store this information. This makes scaling easy, as developers don’t have the worry about the capacity on a single system behind the software. It also allows the system, rather than the developer, to worry about how best to make sure that data is backed up in case of the failure of a machine or network connection.

·         Cinder is a block storage component, which is more analogous to the traditional notion of a computer being able to access specific locations on a disk drive. This more traditional way of accessing files might be important in scenarios in which data access speed is the most important consideration.

·         Neutron provides the networking capability for OpenStack. It helps to ensure that each of the components of an OpenStack deployment can communicate with one another quickly and efficiently.

·         Horizon is the dashboard behind OpenStack. It is the only graphical interface to OpenStack, so for users wanting to give OpenStack a try, this may be the first component they actually “see.” Developers can access all of the components of OpenStack individually through an application programming interface (API), but the dashboard provides system administrators a look at what is going on in the cloud, and to manage it as needed.

·         Keystone provides identity services for OpenStack. It is essentially a central list of all of the users of the OpenStack cloud, mapped against all of the services provided by the cloud which they have permission to use. It provides multiple means of access, meaning developers can easily map their existing user access methods against Keystone.

·         Glance provides image services to OpenStack. In this case, "images" refers to images (or virtual copies) of hard disks. Glance allows these images to be used as templates when deploying new virtual machine instances.

·         Ceilometer provides telemetry services, which allow the cloud to provide billing services to individual users of the cloud. It also keeps a verifiable count of each user’s system usage of each of the various components of an OpenStack cloud. Think metering and usage reporting.

·         Heat is the orchestration component of OpenStack, which allows developers to store the requirements of a cloud application in a file that defines what resources are necessary for that application. In this way, it helps to manage the infrastructure needed for a cloud service to run.

·         And soon

Who is OpenStack for?

You may be an OpenStack user right now and not even know it! As more and more companies begin to adopt OpenStack as a part of their cloud toolkit, the universe of applications running on an OpenStack backend is ever-expanding.

Q: What is it that makes OpenStack Networking so special? Why does it matter?

With Nova you can spin up virtual machines and it provides basic network capabilities. But when you want to use newer technologies, say, tunneling to provide network isolation between tenants or VXLAN – you can’t really leverage those with Nova networking. It limits you to VLAN’s or flat networking. The new technologies enable the biggest benefits of OpenStack Networking: scalable tenant isolation.

     Explain what is OpenStack?

OpenStack is a set of software tools for managing and building cloud computing platforms for private and public clouds. It’s a free and open source software cloud computing platform.

2)      Mention what are the three components that make modular architecture of OpenStack?

The three components that make modular architecture for OpenStack are

·          OpenStack Compute: For managing large networks of the virtual machine

·          OpenStack Object Storage: A storage system that provides support for both block storage and object storage

·          Image Service:  The delivery service provides discovery and registration for virtual disk images

3)      Give an overview of OpenStack Services?

OpenStack offers services like

·          Keystone: Provides authorization and authentication for users

·          Glance: Manages images in different formats

·          Cinder: Provides persistent block storage

·          Neutron: Enables users to create and attach interfaces to networks

·          Nova: Provides instances on user’s demand

·          Swift: Storage platform integrated directly into applications

·          Ceilometer: Openstack for billing

·          Heat: Allows automated infrastructure deployment

4)      What does “role” and “tenant” indicates in OpenStack?

In OpenStack, a tenant is referred for the group of users while role indicates the authorization level of the user.

5)      Explain what hypervisor is and what type of hypervisor does OpenStack supports?

Hypervisor is a piece of computer software or hardware that creates and run virtual machines. A system on which one or more virtual machines is defined is referred as host machine.

The types of hypervisor that supports OpenStack are

·          KVM

·          VMware

·          Containers

·          Xen and HyperV

6)      What are the two types of storage does OpenStack Compute provides?

OpenStack provides two classes of block storage,

·          Ephemeral Storage:  It is associated with a single unique instance. Based on the instance, the size is defined. When the instance associated with it is terminated, data on ephemeral storage ceases to exist

·          Volume Storage:   This storage is not dependent on any particular instance and is persistent.  Volumes are user created and within Quota

7)      What are the basic functions of Identity Service in OpenStack?

The basic functions of Identity Service is

·          User Management:  It tracks the users and their permissions

·          Service Catalog: It provides a catalog of available services with their API endpoints

8)      What are the main components of identity user management?

·          Users: It is a digital representation of a person, service or system who uses OpenStack cloud services

·          Tenants: A container used to group or isolate resource or identity objects.  Depending on service operator a tenant may map to a customer, account, organization or project

·          Roles:  A role includes a set of rights and privileges.  A role determines what operations a user is permitted to perform in a given tenant

9)      Mention what are the networking options used in OpenStack?

The networking options used in OpenStack are

·          Flat Network Manager: IP addresses for VM instances are fetched from the subnet, and then injected into the image on launch

·          Flat DHCP Network Manager:  IP addresses for VM instances are fetched from the subnet specified by the network administrator

·          VLAN Network Manager: Compute creates a VLAN and bridge; DHCP server is started for each VLAN to pass out IP addresses to VM instances.

10)   What is the meaning of term “Cinder” in OpenStack service?

For handling persistent storage for virtual machines, OpenStack provides the service referred as Cinder. There are multiple backends for cinder.  The one that is utilized by default is LVM, called Cinder-Volumes.

11)   List out the storage locations for VM images in OpenStack?

·          OpenStack Object Storage

·          Filesystem

·          S3

·          HTTP

·          RBD or Rados Block Device

·          GridFS

12) Explain what is Cells in OpenStack?   

Cells functionality enables you to scale an OpenStack Compute cloud in a more simplistic way.  When this functionality is enabled, the hosts in an OpenStack Compute cloud are partitioned into group called cells. Cells are configured as trees.

13)   For networking, what hardware is used in OpenStack?

In OpenStack, networking is done in following ways

·          Networks

·          Routers

·          Subnets

·          Ports

·          Vendor Plug-ins

14)   Explain how you can transfer volume from one owner to another in OpenStack?

You can transfer a volume from one owner to another by using the command cinder transfer*.

15)   What is the command to manage floating IP addresses in OpenStack?

nova floating-ip-*

16)   What is bare-metal node and what does it comprised of?

It gives access to control bare metal driver, through which you can control physical hardware resources on the same network.

Bare metal node is comprised of two separate components

·          Bare metal node Orchestrator: It’s a management software, which acts as a dispatcher to all nodes in the cluster.

·          Bare metal node Operating System: It is a base software, which runs on each node in the cluster.

17)   Mention what is the command to remove network interface from bare-metal node?

To remove network interface from bare-metal node command used is bare-metal – interface remove.

18)   Explain what is the function of Cinder Scheduler?

Cinder Scheduler or routing volume create requests to the appropriate volume service

19)   Explain what is Token in OpenStack?

Token is an alpha-numeric string which allows access to a certain set of services depending upon the access level of the user

20)   Explain about OpenStack Python SDK?

For writing python scripts and managing in Openstack cloud, SDK (Software Development Kit) is used.  The SDK implements Python binding to the OpenStack API, which enables you to achieve automation tasks in Python by making calls on Python objects instead of making REST calls directly.

21)   What is the command used for pause and unpause an instance?

·          To pause an instance, command used is $ nova pause INSTANCE_NAME

·          To unpause an instance, command used is $ nova unpause INSTANCE_NAME

22)   What is the command used to list IP address information?

$ nova floating-ip-pool-list

23)   What is the meaning of term “flavor” in OpenStack?

A flavour is an available hardware configuration for a server, which defines the size of a virtual server that can be launched.