OpenStack Interview Questions and Answers

July 27th, 2019

OpenStack Interview Questions and Answers

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Best OpenStack Interview Questions and Answers

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Openstack is a set of software tools that are used for building and managing clod computing platforms for both private and public clouds. Many big companies think that is the future of cloud computing.

Q1) What do you understand by the term Openstack?

Answer: Openstack is defined as the future of cloud computing wherein Openstack can be used for handling a large group of virtual machines with the help of the graphical user interface. The working of Openstack is similar to Linux and it is free and open-source.

Q2) What is the difference between OpenStack and AWS?

Answer: Following is the table explaining the difference between Openstack and AWS:

Parameter	Openstack	AWS
OS (Operating System) used	Operating system provided by AMIs through AWS	Operating system provided by the cloud administrator
License	Open-source	Provided by Amazon
Repetition of operations	Done through text files	Done through templates

Q3) What are the advantages of using Openstack?

Answer: Following are the advantages of using Openstack:

For IT users, it can provide a strong foundation when it comes to delivering the self-storage.
Easy to handle low-cost storage.
Licensing fees can be managed by using Openstack as virtual machines are used.

Q4) What are the key features of Openstack?

Answer: Following are the key features of Openstack:

Horizon: It is the first key feature through which administrators get an idea about the functioning of the cloud.
Nova: It is used for handling multiple virtual machines and other computing tasks.
Swift: It is used for understanding the storage system.
Cinder: It is used as a block storage system so as to access files at a faster speed.
Neutron: It is used for building the connectivity between the components while they are developed.
Keystone: It is used for providing the identity list and is used as mapping techniques.
Glance: It is used for providing the image information of hard disks where images are used as templates.
Ceilometer: It is used for providing billing services to cloud users.
Heat: It is used for maintaining the cloud infrastructure and also allowing developers to illustrate the cloud requirements.

Q5) How many types of storages are provided by the Openstack?

Answer: Openstack provides two types of storages:

Ephemeral storage
Persistent storage

Q6) What are the three types of persistent storage provided by Openstack?

Answer: Following are the three types of persistent storage provided by Openstack:

Object storage
Block storage
File-based storage

Q7) What does the term “object storage” mean?

Answer: Object storage is applied in Openstack with the help of Object Storage service (swift). With the help of REST API, users can access binary objects. Following are the other advantages of object storage:

Openstack stores all its virtual machine images in the object storage system.
Object storage works with the Openstack dashboard.
Object storage systems can be used for multiple data centers.

Q8) What does the term “block storage” mean?

Answer: Block storage is applied in Openstack with the help of Block storage service (cinder). Block storage provides multiple back ends in the form of drivers. Since it is persistent storage it can be detached and reattached from one instance to another.

Q9) What does the term “file-based storage” mean?

Answer: The file-based storage system in Openstack provides a set of services that are used for managing multiple files at the same time and also can be exchanged with multiple users at the same time.

Q10) What is the difference between ephemeral storage, block storage, object storage, and file-based storage?

Answer: Following is the table explaining the difference between ephemeral storage, block storage, object storage, and file-based storage:

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Q11) Name a few commodity storage technologies

Answer: Following are the commodity storage technologies:

Ceph
LVM
Gluster
Sheepdog
NFS
iSCSI
ZFS

Q12) What does the term “Sheepdog” mean?

Answer: Sheepdog is one of the commodity storage which is used as a userspace distributed storage system. It has a powerful virtual disk management features such as rollback, cloning, snapshot, and thin provisioning.

Q13) What does the term “ZFS” mean?

Answer: ZFS provides the back-ends for Openstack block storage which is supported by the Solaris-based system like Illumos. It has many advantages over ext4.

Q14) What are the advantages of Ceph?

Answer: Following are the advantages of Ceph:

The control over data distribution and replication strategies are good in Ceph.
It is used as a support system for fast booting from the volume.
The object storage and block storage are consolidated.

Q15) Define the following terms from Openstack:

User: Users are members of multiple projects.
Tenant: It is also known as project or accounts which refers to the group of users. The projects refer to the organizational units of cloud processing.
Role: It is defined as the position which is used for mapping the user.

Q16) What is the keystone identity service in Openstack?

Answer: Keystone identity service is the most important identity service in Openstack and it is used for executing complete Openstack identity API. it is responsible for user management and service catalog. It is used for tracking users and their permissions.

Q17) Name a few storage locations for virtual machine images in Openstack.

Answer: Following are the storage locations for virtual machine images in Openstack:

Openstack object storage
Filesystem
HTTP
S3
Rados Block Device
GridFSMaster Openstack

Q18) Name a few networking hardware in Openstack.

Answer: Following are the networking hardware in Openstack:

Subnets
Ports Vendor Plugins
Routers
Networks

Q19) Name a few commands to generate key pairs.

Answer: Following are the commands to generate key pairs:

ssh-keygen
ssh
nova keypair-add-pub_key id_rsa.pub mykey

Q20) Name a few components of the OpenStack to compute.

Answer: Following are the components of the OpenStack compute:

Scheduler
Volume worker
Nova-network
Nova-compute
Rabbit-MQ server
API server

Q21) What is Hypervisor?

Answer: Hypervisor is used as a term for defining a virtual machine monitor which includes hardware, software, and firmware components that run on the virtual machine. There are multiple hypervisors in Openstack.

Q22) Name a few hypervisors supported by the Openstack.

Answer: Following are the hypervisors supported by the Openstack:

Kernal-based virtual machine
Linux Containers having Linux-based virtual machines
Quick EMUlator used for development purposes
Used Mode Linux used for development purpose
Server visualization with Microsoft’s Hyper-V

Q23) What are the different networking options in Openstack?

Answer: Following are the different networking options in Openstack:

Retry filter
Instance locality filter
Availability zone filter
Capacity filter
Different back-end filter

Q24) What is the function of the filter scheduler?

Answer: The function of the filter scheduler is to provide support for compute nodes and also filtering and weighting to notify where a new instance has to be created. It first creates a dictionary for unfiltered hosts which is then filtered based on their properties.

Q25) What are the commands used for pausing and unpausing an instance?

Answer: Following are the two commands used for pausing and unpausing an instance:

$ novaunpause INSTANCE_NAME
$ nova pause INSTANCE_NAME

Q26) Name the three important modular architecture of Openstack.

Answer: Following are the three important modular architecture of Openstack:

Openstack compute: It is used for managing large networks on the virtual machine.
Image service: It is used for providing delivery service for discovering and registering of the virtual machine images.
Openstack object storage: It is used as a storage system provides support for two different storage: object storage and block storage.

Q27) Which command is used for managing floating IP addresses in Openstack?

Answer: Following is the command used for managing floating IP address in Openstack:
nova floating-ip-*

Q28) Is it possible to see the list of roles and associated IDs in Openstack?

Answer: Yes, it is possible to see the list of roles and associated IDs in Openstack.

Q29) How can we see the list of roles and associated IDs in Openstack?

Answer: By using the keystone role list we can see the list of roles and associated IDs in Openstack.

Q30) Name the command used for assigning a project or tenant to a user.

Answer: By using the command sudo nova-manage a project or tenant can be assigned to a user.

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Q31) Name the command used for creating a user in Openstack.

Answer: By using the command sudo nova-manage a user can be created in Openstack.

Q32) Define the term “flavor” in Openstack.

Answer: The term flavor refers to an available hardware configuration of a server that is used for defining the size of the virtual server that is to be launched.

Q33) Name the command that is used for listing IP address information.

Answer: The command used for listing IP address information is as follows:
$ nova floating-ip-pool-list

Q34) What do you understand by Python SDK in Openstack?

Answer: SDK stands for Software Development Kit which is used for writing scripts related to python. It provides a platform for Openstack where all the services are done in one place. It consists of languages that bind access to the OpenStack clouds, and complete API reference with easy interaction with REST API.

Q35) What is the role of the API server?

Answer: The role of the API server is to provide an interface between the external world and the cloud infrastructure.

Q36) What does a bare-metal node mean?

Answer: A bare-metal node is used for the single-tenant cloud with high performance cluster computing. It also grants access to the bare-metal driver which is used for handling the provision of Openstack compute.

Q37) What does token mean in Openstack?

Answer: Token is defined as a type of authentication which is similar to password-based validation. Once the credentials are inserted by the user, the token gets generated through which the user gets authentication for keystone. With the generated token, the user can access the Openstack. The token comes for a limited time period. Once the time period is exceeded, it has to be renewed again.

Q38) What does a flat network manager mean?

Answer: A flat network manager is a place where all the virtual machines are using a single network, the same subnet, and bridge as created by the administrator. Therefore, all the virtual machines are said to be interconnected and are known as a flat network manager.

Q39) What is VLAN?

Answer: VLAN is used for providing more secure and separate networks for virtual machines. For every tenant, it has a separate IP range, bridge, and virtual network. This is the most favored choice of every multi-tenant or project environment.

Q40) What is a flat DHCP network manager?

Answer: A flat DHCP network manager is very much similar to the flat network manager except for the IP addresses that are assigned to the virtual machines are through DHCP. DHCP stands for Dynamic Host Configuration Protocol.

Q41) What is the function of the cinder scheduler?

Answer: The function of the cinder scheduler is that it creates requests for appropriate volume service. It is also known as routing volume.

Q42) Name the command used for removing network interface from the bare-metal node.

Answer: The command used for removing the network interface from the bare-metal node is bare-metal-interface remove.

Q43) What does a bare-metal node consist of?

Answer: A bare-metal node consists of the following two things:

Bare-metal node orchestrator
Bare-metal node operating system

Q44) What is a bare-metal node orchestrator?

Answer: A bare-metal orchestrator is management software. For all the nodes in the cluster, it acts as a dispatcher.

Q45) What is a bare-metal node operating system?

Answer: A bare-metal node operating system is a base software. It used for running every node in the cluster.

Q46) Name the command used for transferring the volume from one owner to another in Openstack.

Answer: The command used for transferring the volume from one owner to another in OpenStack is cinder transfer*.

Q47) What do cells mean in Openstack?

Answer: Cells are the groups that are partitioned from the hosts of the Openstack compute cloud. These cells are later framed as trees.

Q48) Name the networking options that are used in OpenStack.

Answer: Following are the networking options that are used in Openstack:

Flat network-manager
Flat DHCP network-manager
VLAN network-manager

Q49) Name the main components of identity user management.

Answer: Following are the main components of identity user management:

Users
Tenants
Roles

Q50) Name the basic functions of identity service in Openstack.

Answer: There are two basic functions of identity service in Openstack:

User management
Service catalog

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Q51) What is OpenStack

Answer: Openstack is cloud computing for the future, it can be used to store a huge number of storage data, by using open stack we can create more virtual environments.

Q52) Benefits of OpenStack

Answer:

It is used to enhance the existing applications or develop new applications for SAAS
It will create a strong foundation for server for developers
It the better efficient scalability for low cost

Q53) Openstack key components?

Answer: Nova,Glance,Swift,Horizon,clinder,Keystone,Heat etc

Q54) Storage of OpenStack?

Answer: Block storage, Ephemeral Storage, Object Storage, Block storage

Q55) Network Manager in OpenStack?

Answer: Dynamic Host Configuration, Virtual Local area network

Q56) unpause and pause instance

Answer:
novaunpause NAME_OF_INSTANCE
nova pause NAME_OF_INSTANCE

Q57) List of VM images in OpenStack

Answer: OpenStack Object Storage
HTTP
Filesystem
GridFSMaster Openstack from industry experts.
S3
RBD or Rados Block Device

Q58) Network hardware in OpenStack

Answer:

Routers
Ports Vendor Plugins
Subnets
Networks

Q59) Know floating IP address command in OpenStack?

Answer: nova floating-IP-*

Q60) Keypair Generation?

Answer:
cd .ssh
ssh-keygen
nova keypair-add –pub_key id_rsa.pub mykey

Q61) What is the role of API Server?

Answer: It will allow the remote server access the user from anywhere

Q62) components of OpenStack?

Answer:
API server
Compute Workers (Nova-Compute)
Message Queue (Rabbit-MQ Server)
Volume Worker
Network controller (Nova-Network)
Scheduler

Q63) Create a user for OpenStack?

Answer: Sudo nova-manage user create user-name

Q64) Assign tenant/project?

Answer: Sudo nova-manage user create user-name

Q65) Can we see the list of roles and associated IDs in the OpenStack environment?

Answer: Yes, by using keystone role-list

Q66) List down the type of Hypervisors supported by OpenStack.

Answer: KVM (Kernel-based Virtual machine)
LXC: Linux Containers having Linux-based VMs
QEMU: Quick EMUlator used for development purposes
UML: User Mode Linux used for development purposes
VMware vSphere: VMware-based Linux and Windows via vCenter server connection.
Hyper-V: Server virtualization with Microsoft’s Hyper-V

Q67) Compare AWS and OpenStack?

Answer: Compare AWS and OpenStack

Criteria	AWS	OpenStack
License	Amazon proprietary	Open Source
Operating System	Whatever cloud administrator provides	Whatever AMIs provided by AWS
Performing repeatable operations	Through templates	Through text files

Q68) Define Identity Service in OpenStack.

Answer: Keystone is the most important and preferred Identity Service in OpenStack and executes the complete OpenStack Identity API. The Keystone Identity Service is responsible for user management and service catalog. In user management, it tracks users and their permissions while Service Catalog offers a list of services available with their API. The former provides authentication credential details of users, tenants, and roles.
Internal services like Token and Policy are also part of Keystone Identity

Q69) What is Token?

Answer: Token is a type of authentication similar to password-based validation. A token gets generated once the user inserts the credentials and authenticates as a Keystone user. The token can then be used to access OpenStack services without any revalidation. It is interesting to note that a token is active for a limited period and must be renewed after regular intervals.
To create a token, users first need to authenticate their Keystone credentials.

Q70) What is OpenStack Python SDK?

Answer: Python SDK (Software Development Kit) helps users to write applications for performing automation tasks in Python by calling Python objects. It provides a platform to work with multiple OpenStack services at one place. It consists of language bindings to access OpenStack clouds, complete API reference, easy interaction with REST API and sample code for initial applications.

Q71) What are the services generally run on a Compute Node?

Answer: Following services run on a compute node,
Nova-Compute
Networking Services like OVS

Q72) What is the default location of VMs on the Compute Nodes?

Answer: VMs in the Compute node is stored at “/var/lib/nova/instances”

Q73) What is the default location of glance images?

Answer: As the Glance service runs on a controller node, all the glance images are stored under the folder “/var/lib/glance/images” on a controller node.

Q74) Tell me the command on how to spin a VM from Command Line?

Answer: We can easily spin a new VM using the following openstack command,
# openstack server create –flavor {flavor-name} –image {Image-Name-Or-Image-ID} –nic net-id={Network-ID} –security-group {Security_Group_ID} –key-name {Keypair-Name} <VM_Name>

Q75) How to list the network namespace of a tenant in OpenStack?

Answer: Network namespace of a tenant can be listed using “IP net ns” command
~# IP netns list
DHCP-a51635b1-d023-419a-93b5-39de47755d2d
haproxy
router

Q76) How to execute command inside network namespace in OpenStack?

Answer: Let’s assume we want to execute “ifconfig” command inside the network namespace “qdhcp-a51635b1-d023-419a-93b5-39de47755d2d”, then run the beneath command,
Syntax : ip netns exec {network-space} <command>
~# IP netns exec qdhcp-a51635b1-d023-419a-93b5-39de47755d2d “ifconfig”

Q77) How to upload and download a cloud image in Glance from the command line?

Answer: A Cloud image can be uploaded in glance from command using beneath OpenStack command,
~# OpenStack image create –disk-format qcow2 –container-format bare –public –file {Name-Cloud-Image}.qcow2 <Cloud-Image-Name>

Q78) How to reset error state of a VM into active in OpenStack env?

Answer: There are some scenarios where some VMs went to an error state and this error state can be changed into active state using below commands,
~# nova reset-state –active {Instance_id}

Q79)How to get a list of available Floating IPs from the command line?

Answer: Available floating IPs can be listed using the below command,
~]# OpenStack ip floating list | grep None | head -10

Q80) How to provision a virtual machine in a specific availability zone and compute Host?

Answer: Let’s assume we want to provision a VM on the availability zone NonProduction in compute-02, use the beneath command to accomplish this.

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