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OpenStack Interview Questions And Answers

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If you are looking for OpenStack Interview Questions And Answers for Experienced 2018, you are at right place. Here Mindmajix sharing a list of 15 interview question on OpenStack. According to the sources, OpenStack has a global share of about 1% and it's growing rapidly. So, You still have the opportunity to move ahead in your career by choosing OpenStack. Mindmajix offers OpenStack Interview Questions that help you in cracking your interview & acquire dream career as OpenStack Engineer.

OpenStack Interview Questions

  1. What is OpenStack?
  2. What are the main components of OpenStack architecture?
  3. What is OpenStack fast-forward upgrades (FFU)?
  4. How is OpenStack used in a cloud environment?
  5. What is Nova?
  6. What is Swift?
  7. What is Cinder?
  8. What is Neutron?
  9. What is Horizon?
  10. What is Keystone?
  11. What is Glance?
  12. What is Ceilometer?
  13. What is Heat?
  14. What is the difference between a VM image and a Docker image?
  15. Is it possible to create an OpenStack image importing an *.ovf file with Glance?

OpenStack Interview Questions And Answers

1) What is OpenStack?

A) OpenStack is a collection of open-source projects that enables an open, scalable cloud infrastructure. The core of OpenStack is meant to provide consistent APIs and interfaces to a variety of potential back-ends.

 

2) What are the main components of OpenStack architecture?

A) OpenStack architecture. Bryant details each of the core projects:

  • Identity (Keystone)
  • Dashboard (Horizon)
  • Orchestration (Heat)
  • Metering (Celiometer)
  • Object stroage (Swift)
  • Image service (Glance)
  • Networking (Quantum now Neutron)
  • Compute (Nova)

 

3) What is OpenStack fast-forward upgrades (FFU)? 

A) FFU lets you move from one OpenStack version to another while skipping the versions between, allowing you to quickly upgrade an OpenStack installation across multiple releases. 

 

4) How is OpenStack used in a cloud environment? 

A) 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-user's computer. 

OpenStack falls into the Infrastructure as a Service (IaaS) category. 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 that are delivered to the end users.

 

5) What is Nova?

A) Nova is the primary computing engine behind OpenStack. It is used for deploying and managing large numbers of virtual machines and other instances to handle computing tasks.

Related Page:: Learn Monitoring Compute services with Munin – OpenStack

Interview Questions on OpenStack

6) What is Swift?

A) 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.

 

7) What is Cinder?

A) 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.

 

8) What is Neutron?

A) 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.

 

9) What is Horizon?

A) 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.

 

10) What is Keystone?

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.

11) What is Glance?

A) 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.

 

12) What is Ceilometer?

A) 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. 

 

13) What is Heat?

A) 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.


14) What is the difference between a VM image and a Docker image?

A) These are some differences between a docker and a VM image which I could list out:

1. Snapshot process is faster in Docker than VMs

We generally start with a base image, and then make our changes, and commit those changes using docker, and it creates an image. This image contains only the differences from the base. When we want to run our image, we also need the base, and it layers our image on top of the base using a layered file system.

File system merges the different layers together and we get what we want, and we just need to run it. Since docker typically builds on top of ready-made images from a registry, we rarely have to "snapshot" the whole OS yourself. This ability of Dockers to snapshot the OS into a common image also makes it easy to deploy on other docker hosts.

2. Startup time is less for Docker than VMs

A virtual machine usually takes minutes to start, but containers take seconds, and sometimes even less than a second.

4. Docker images have more portability

Docker images are composed of layers. When we pull or transfer an image, only the layers we haven’t yet in the cache are retrieved. That means that if we use multiple images based on the same base Operating System, the base layer is created or retrieved only once. VM images don't have this flexibility.

5. Docker provides versioning of images

We can use the docker commit command. We can specify two flags: -m and -a. The -m flag allows us to specify a commit message, much like we would with a commit on a version control system:

$ sudo docker commit -m "Added json gem" -a "Kate Smith"
0b2616b0e5a8 ouruser/sinatra:v2
4f177bd27a9ff0f6dc2a830403925b5360bfe0b93d476f7fc3231110e7f71b1c
6. Docker images do not have states

In Docker terminology, a read-only Layer is called an image. An image never changes. Since Docker uses a Union File System, the processes think the whole file system is mounted read-write. But all the changes go to the top-most writeable layer, and underneath, the original file in the read-only image is unchanged. Since images don't change, images do not have state.

7. VMs are hardware-centric and docker containers are application-centric

Let's say we have a container image that is 1GB in size. If we wanted to use a Full VM, we would need to have 1GB times x number of VMs you want. In docker container we can share the bulk of the 1GB and if you have 1000 containers we still might only have a little over 1GB of space for the containers OS, assuming they are all running the same OS image.

8. Supported image formats

Docker images:

bare. The image does not have a container or metadata envelope.
ovf. The OVF container format.
aki. An Amazon kernel image.
ari. An Amazon ramdisk image.
ami. An Amazon machine image.


VM images:

raw. An unstructured disk image format; if you have a file without an extension it is possibly a raw format
vhd. The VHD disk format, a common disk format used by virtual machine monitors from VMware, Xen, Microsoft, VirtualBox, and others
vmdk. Common disk format supported by many common virtual machine monitors
vdi. Supported by VirtualBox virtual machine monitor and the QEMU emulator
iso. An archive format for the data contents of an optical disc, such as CD-ROM.
qcow2. Supported by the QEMU emulator that can expand dynamically and supports Copy on Write
aki. An Amazon kernel image.
ari. An Amazon ramdisk image.
ami. An Amazon machine image.

15) Is it possible to create an OpenStack image importing an *.ovf file with Glance?

EDIT_1: I'm interested on creating images just providing its ovf file.

A) You can import an .ovf into Glance, but it does not currently have the ability to extract any data out of it. Future releases may have this functionality.

 

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