SoorajSoman – Best DevOps

What is Pod in kubernetes.

SoorajSoman — Wed, 01 Sep 2021 08:28:35 +0000

Pods are the atomic unit of kubernetes.
Pod is a group of one or more containers.
Pods can only be instantiated not created.
Pods can be created using yaml or json.
Pod has multiple states. Running, Pending and succeeded/failed
Each pod connects to common pod network
Pods can only be instantiated not created
Service serves as an internal load balancer for pod
Each pod has an ip and port
If more than one container are available in a pod. Each container will have a sperate port address

What are the components of Kubernetes worker and explain each component’s function?

SoorajSoman — Wed, 01 Sep 2021 07:19:09 +0000

<strong>kubeletstrong>
An agent that runs on each node in the cluster. It makes sure that containers are running in a Pod.

<strong>kube-proxystrong>
kube-proxy is a network proxy that runs on each node in your cluster. kube-proxy maintains network rules on nodes. These network rules allow network communication to your Pods from network sessions inside or outside of your cluster.

<strong>Container runtimestrong> 
The container runtime is the software that is responsible for running containers.

What are the components of Kubernetes master and explain each component’s function?

SoorajSoman — Wed, 01 Sep 2021 07:12:04 +0000

Kubernetes master node contains 4 components kube-apiserver, etcd, kube-scheduler, kube-controller-manager

<strong>kube-apiserverstrong>
The API server is a component of the Kubernetes master node that exposes the Kubernetes API. The API server is the front end for the Kubernetes control plane.

<strong>etcdstrong>
Consistent and highly-available key value store used as Kubernetes' backing store for all cluster data.

<strong>kube-schedulerstrong>
Control plane component that watches for newly created Pods with no assigned node, and selects a node for them to run on.
Factors taken into account for scheduling decisions include: individual and collective resource requirements, hardware/software/policy constraints, affinity and anti-affinity specifications, data locality, inter-workload interference, and deadlines.

<strong>kube-controller-managerstrong>
Manager/Controller of Controllers such as Node Controller, Endpoint controller, Namespace controller etc. Helps maintain the desired state.

Write down 10 features of Kubernetes with image

SoorajSoman — Wed, 01 Sep 2021 06:55:13 +0000

<strong>Automated Schedulingstrong> : Kubernetes provide advance scheduler which helps to schedules the work to the worker nodes

<strong>Self Healingstrong> : Kubernetes reschedule/restart/replaces the misfunctioned or died containers.

<strong>Horizontal scaling strong>: Kubernetes can scale up or scale down the application as per the requirements.

<strong>Service discovery and load balancingstrong> : No need to modify your application to use an unfamiliar service discovery mechanism. Kubernetes gives Pods their own IP addresses and a single DNS name for a set of Pods, and can load-balance across them.

<strong>Batch executionstrong> : Kubernetes can manage your batch and CI workloads, replacing containers that fail, if desired.

<strong>Automatic bin packingstrong> : Automatically places containers based on their resource requirements and other constraints, while not sacrificing availability.

<strong>Designed for extensibilitystrong> : Add features to your Kubernetes cluster without changing upstream source code.

<strong>Storage orchestrationstrong> : 
Automatically mount the storage system of your choice.

List out number of storage/volume drivers supported by docker?

SoorajSoman — Tue, 31 Aug 2021 09:19:31 +0000

Azure File Storage plugin

BeeGFS Volume Plugin

Blockbridge plugin

Contiv Volume Plugin

Convoy plugin

DigitalOcean Block Storage plugin

DRBD plugin

Flocker plugin

Fuxi Volume Plugin

gce-docker plugin

GlusterFS plugin

Horcrux Volume Plugin

HPE 3Par Volume Plugin

Infinit volume plugin

IPFS Volume Plugin

Keywhiz plugin

Local Persist Plugin

NetApp Plugin (nDVP)

Netshare plugin

Nimble Storage Volume Plugin

OpenStorage Plugin

Portworx Volume Plugin

Quobyte Volume Plugin

REX-Ray plugin

Virtuozzo Storage and Ploop plugin

VMware vSphere Storage Plugin

List out all INSTRUCTION statement of dockerfile and give one line explanation.

SoorajSoman — Tue, 31 Aug 2021 09:12:38 +0000

Docker Instructions
FROM  : For using the base image. Eg. FROM ubuntu
ARG   : Used to create re-usable variables. Eg. ARG user=sooraj ... ${user}
MAINTAINER : Used to set the creator name in Metadata Eg. MAINTAINER SoorajSoman <>
RUN   : Used to run command Eg. RUN apt-get update
EXPOSE : Used to give port information Eg. EXPOSE 80
USER  : To specify the runtime user Eg. USER guest
COPY  : Used to copy files Eg. COPY test.txt /mydir
ADD  : Used to add/extract files to the filesystem Eg.ADD test.txt /mydir
CMD : Used to set PID 1 Eg. CMD echo "Hello world"
ENTRYPOINT : Used to set PID 1 Eg. ENTRYPOINT ["/bin/echo", "Hello"]
VOLUME : Create/mount a volume to the docker container from the docker host file system.Eg. VOLUME /myvol
ENV  : Used to set environment variables Eg. ENV MY_NAME="Sooraj Soman"
WORKDIR : Used to set the working directory Eg. WORKDIR
 /path/to/workdir

Create one Image which have base as ubuntu and with git – ntp – apache2.

SoorajSoman — Tue, 31 Aug 2021 05:46:59 +0000

docker run --name custom_ubuntu -itd ubuntu
docker attach custom_ubuntu
apt-get update
apt-get install git
apt-get install ntp
apt-get install apache2
docker commit -a"Sooraj Soman" -m"ub-up-git-ntp-apache2" custom_ubuntu ub-up-git-ntp-apache2

Create one Image which have base as centos and with git – ntp – httpd.

SoorajSoman — Tue, 31 Aug 2021 05:43:42 +0000

docker run --name custom_centos -itd centos
docker attach custom_centos
yum update
yum install git
yum install ntp
yum install httpd
docker commit -a"Sooraj Soman" -m"cent-up-git-ntp-httpd" custom_centos cent-up-git-ntp-httpd

What is Docker Images?

SoorajSoman — Tue, 31 Aug 2021 05:31:23 +0000

Docker image is a collection of files systems.
A docker image is a template for docker container.
One docker image can be used to create multiple containers
File systems are layered over each other
Layer 0 have the root filesystem
Each layer in image will have 40 character length UUID generated by SHA 256 algorithm.
All layers in a docker image is Read only.
All layers in an image is merged to one layer while creating the container..

What is Storage Driver and types of Storage Driver?

SoorajSoman — Tue, 31 Aug 2021 05:20:55 +0000

Storage driver controls how images and containers are stored and managed in docker host. 
Types of Storage Drivers
overlay2,fuse-overlayfs,
aufs,devicemapper
,btrfs
,zfs

What is the use of “docker update” commands?

SoorajSoman — Mon, 30 Aug 2021 15:16:51 +0000

Docker Update command used to update the default configuration of the container.
Eg. Changing number CPUs, Memory etc.

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What is the difference between docker pause and docker un-pause?

SoorajSoman — Mon, 30 Aug 2021 07:34:03 +0000

"docker pause" command suspends all process related to that container 
"docker un-pause" command un-suspends all process related to that container

What is the difference between docker stop and docker kill?

SoorajSoman — Mon, 30 Aug 2021 07:31:53 +0000

Both the commands used to stop the running container
. "docker stop" command stops the container gracefully where "docker kill" command forces container to stop immediately.

Explain What is Docker Container with image?

SoorajSoman — Mon, 30 Aug 2021 07:25:40 +0000

Docker Container is a lightweight independent application run environment and docker image is a collection of file system which is used to run a container. Using one docker image we can create multiple containers.