rajukumar – Best DevOps https://www.bestdevops.com Lets Learn, Do it & Share! Thats a Best DevOps!!! Fri, 04 Feb 2022 10:18:21 +0000 en-US hourly 1 https://wordpress.org/?v=7.1.3 Create a namespace with your name and assigne one dummy resourcesquota to it and deploy some app https://www.bestdevops.com/create-a-namespace-with-your-name-and-assigne-one-dummy-resourcesquota-to-it-and-deploy-some-app/ Fri, 03 Sep 2021 05:07:00 +0000 https://www.bestdevops.com/?p=20805 [centos@ip-172-31-15-134 ~]$ kubectl create ns raju namespace/raju created resource.yaml apiVersion: v1 kind: ResourceQuota metadata: name: mem-cpu-demo spec: hard: requests.cpu: "1" requests.memory: 1Gi limits.cpu: "2" limits.memory: 2Gi kubectl apply -f resource.yaml -n raju resourcequota/mem-cpu-demo created kubectl get resourcequota mem-cpu-demo --namespace=raju NAME AGE REQUEST LIMIT mem-cpu-demo 2m2s requests.cpu: 0/1, requests.memory: 0/1Gi limits.cpu: 0/2, limits.memory: 0/2Gi [centos@ip-172-31-15-134 raju]$ kubectl apply -f https://k8s.io/examples/admin/resource/quota-mem-cpu-pod.yaml --namespace=raju Error from server (Forbidden): error when creating "https://k8s.io/examples/admin/resource/quota-mem-cpu-pod.yaml": pods "quota-mem-cpu-demo" is forbidden: exceeded quota: mem-cpu-demo, requested: requests.memory=600Mi, used: requests.memory=700Mi, limited: requests.memory=1Gi Got error when resource is exceeded. Name: raju Labels: kubernetes.io/metadata.name=raju Annotations: <none> Status: Active Resource Quotas Name: mem-cpu-demo Resource Used Hard -------- --- --- limits.cpu 800m 2 limits.memory 1Gi 2Gi requests.cpu 400m 1 requests.memory 700Mi 1Gi No LimitRange resource. ]]> What are the components of Kubernetes worker and explain each component’s function? https://www.bestdevops.com/what-are-the-components-of-kubernetes-worker-and-explain-each-components-function-5/ Wed, 01 Sep 2021 07:01:04 +0000 https://www.bestdevops.com/?p=20557

kubelet

The kubelet takes a set of PodSpecs that are provided through various mechanisms and ensures that the containers described in those PodSpecs are running and healthy.

kube-proxy

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.

container runtime like docker ctr

]]> What are the components of Kubernetes master and explain each component’s function? https://www.bestdevops.com/what-are-the-components-of-kubernetes-master-and-explain-each-components-function-4/ Wed, 01 Sep 2021 06:50:26 +0000 https://www.bestdevops.com/?p=20495 kube-api-server The API server is the front end for the kube master

etcd – act as cluster data storage

Scheduler assign tasks to the worker node

controller manager manages the desire number of pods and notifies if something goes down

]]> Q1. List out all INSTRUCTION statement of dockerfile and give one line explanation. https://www.bestdevops.com/q1-list-out-all-instruction-statement-of-dockerfile-and-give-one-line-explanation-2/ Tue, 31 Aug 2021 08:44:01 +0000 https://www.bestdevops.com/?p=20414 FROM – base OS we require to build our apps

RUN – Run command in a container created from previous line/layer

ARG – Set a variable for docker file

ENV – set environment for the container

EXPOSE – Sepcify information port for the container and also can be used during port forwarding

COPY – Copy the file in the destination
ADD – Copy the folder in the destination

USER – specify the user to run PID1

WORKDIR – to set workdir so we dont have to give the entire path all the time.

CMD – To set the PID1. This can be replaced while starting the container using “docker run <image name> <process/command>”

ENTRYPOINT – To set the PID1. This can not be replaced while starting. Any parameter passing in docker run will consider parameters for PID1 “docker run <image name> <params>”

]]> Write a example docker file with 2 CMD, 2 ENTRYPOINT https://www.bestdevops.com/write-a-example-docker-file-with-2-cmd-2-entrypoint/ Tue, 31 Aug 2021 07:11:45 +0000 https://www.bestdevops.com/?p=20357 FROM ubuntu MAINTAINER Raju << raju.shankar@quest-global.com>> ENV DEBIAN_FRONTEND=noninteractive RUN apt-get update RUN apt-get -y install tzdata RUN apt-get update && apt-get install git -y && apt-get install -yq apache2 CMD echo "Hello world from first cmd" CMD echo "Hello world from second cmd" ENTRYPOINT ["/bin/echo","HEllo from first entrypoint"] ENTRYPOINT ["/bin/echo","HEllo from second entrypoint"]

Test1:

docker run 27d064e1c81a
HEllo from second entrypoint /bin/sh -c echo “Hello world from second cmd”

Test2:

root@ip-172-31-28-155:/home/ubuntu/raju# docker run 27d064e1c81a echo test
HEllo from second entrypoint echo test

Explanation:

Only the second cmd or entrypoint is being considered. Moreover if we try to replace cmd during run time then second entrypoint and run time cmd is considered.

]]> What is Storage Driver and types of Storage Driver? Explained with Images. https://www.bestdevops.com/what-is-storage-driver-and-types-of-storage-driver-explained-with-images-8/ Tue, 31 Aug 2021 05:34:59 +0000 https://www.bestdevops.com/?p=20283 Ideally, very little data is written to a container’s writable layer, and you use Docker volumes to write data. However, some workloads require you to be able to write to the container’s writable layer. This is where storage drivers come in.

]]> Create one Image which have base as ubuntu and with git – ntp – apache2. https://www.bestdevops.com/create-one-image-which-have-base-as-ubuntu-and-with-git-ntp-apache2/ Tue, 31 Aug 2021 05:07:02 +0000 https://www.bestdevops.com/?p=20220 05bf5be23f40 ubuntu:latest "bash" 12 seconds ago Up 11 seconds ubunturajucontainer root@ip-172-31-28-155:/home/ubuntu# docker exec -it 05bf5be23f40 /bin/sh apt-get update apt-get install git apt-get install apache2 apt-get install httpd # read escape sequence root@ip-172-31-28-155:/home/ubuntu# docker commit -a "raju" -m "ubuntu-httpd-apache" 05bf5be23f40 ubuntu-with-git-apache ]]> Create one Image which have base as centos and with git – ntp – httpd. https://www.bestdevops.com/create-one-image-which-have-base-as-centos-and-with-git-ntp-httpd/ Tue, 31 Aug 2021 04:56:42 +0000 https://www.bestdevops.com/?p=20210 

root@ip-172-31-28-155:/home/ubuntu# docker ps | grep raju
ad134985b915   centos         "/bin/bash"          9 seconds ago        Up 7 seconds                  rajucentoscontaniner

root@ip-172-31-28-155:/home/ubuntu# docker exec -it ad134985b915 /bin/sh
yum install git
yum install httpd
sh-4.4# read escape sequence
root@ip-172-31-28-155:/home/ubuntu# docker commit -a "Raju" -m "cent-os-commit-raju" ad134985b915 centos-withgitandhttpd
]]> What is the use of “docker update” commands? with example and image https://www.bestdevops.com/what-is-the-use-of-docker-update-commands-with-example-and-image-5/ Mon, 30 Aug 2021 11:31:24 +0000 https://www.bestdevops.com/?p=20109

Docker update command updates the container properties. In the below example I have update –memory-reservation

Before updating :
docker inspect 8de604debbb0
"MemoryReservation": 0,


After updating: docker update 8de604debbb0 --memory-reservation 50M
"MemoryReservation": 52428800,
]]> List of Top 5 docker images from hub.docker.com and create a running container of it and try to use it. https://www.bestdevops.com/list-of-top-5-docker-images-from-hub-docker-com-and-create-a-running-container-of-it-and-try-to-use-it/ Mon, 30 Aug 2021 11:16:17 +0000 https://www.bestdevops.com/?p=20078 Image 1: Ran golang image and executed the image to get the go version.

Image2:Ran python image and executed the container

Image3:Ran openjdk image and executed the container for java version

Image4:Searched for some fun image and got cat image

(docker run –rm -it wernight/funbox nyancat)

Image5: Create a container for alpine image and excuted to add curl into the container

Image1
root@ip-172-31-28-155:/home/ubuntu# docker run -itd --name rajucontainer golang
8de604debbb0a9a279c7f135cb10fc4ceb6d86a1b2ece63858e64a810f75c9b9
root@ip-172-31-28-155:/home/ubuntu# docker exec -it rajucontainer /bin/sh
# go version
go version go1.17 linux/amd64

Image2
root@ip-172-31-28-155:/home/ubuntu# docker run -itd --name rajupycontainer python
a0ae7dc373c4456a31fa993b84656589f1e67a8701fe8fcd17cd63604c715cf8
root@ip-172-31-28-155:/home/ubuntu# docker exec -it a0ae7dc373c4456a31fa993b84656589f1e67a8701fe8fcd17cd63604c715cf8 /bin/bash
root@a0ae7dc373c4:/# python version
python: can't open file '//version': [Errno 2] No such file or directory
root@a0ae7dc373c4:/# python
Python 3.9.6 (default, Aug 17 2021, 15:37:33)
[GCC 10.2.1 20210110] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> 

Image3
root@ip-172-31-28-155:/home/ubuntu# docker run -itd --name rajujavacnew1 openjdk:latest
f4be5b57b8dc5c1981fef16df652bf3ae4deaf6aeb59902df703c5490a8dfe74
root@ip-172-31-28-155:/home/ubuntu# docker ps | grep raju
f4be5b57b8dc   openjdk:latest   "jshell"                 3 seconds ago    Up 2 seconds                                                          rajujavacnew1


Image5
root@ip-172-31-28-155:/home/ubuntu# docker run -itd --name rajualpinec alpine
f9b774b8c4d795ac0db94cf26a55b2da16a849d3cccda33a30c1b21d7dd3c1ac
root@ip-172-31-28-155:/home/ubuntu# docker exec -it f9b774b8c4d795ac0db94cf26a55b2da16a849d3cccda33a30c1b21d7dd3c1ac
"docker exec" requires at least 2 arguments.
See 'docker exec --help'.

Usage:  docker exec [OPTIONS] CONTAINER COMMAND [ARG...]

Run a command in a running container
root@ip-172-31-28-155:/home/ubuntu# docker exec -it f9b774b8c4d795ac0db94cf26a55b2da16a849d3cccda33a30c1b21d7dd3c1ac /bin/sh
/ # apk update && apk add curl
fetch https://dl-cdn.alpinelinux.org/alpine/v3.14/main/x86_64/APKINDEX.tar.gz
fetch https://dl-cdn.alpinelinux.org/alpine/v3.14/community/x86_64/APKINDEX.tar.gz
v3.14.1-104-g035eb230f7 [https://dl-cdn.alpinelinux.org/alpine/v3.14/main]
v3.14.2-1-g0312522127 [https://dl-cdn.alpinelinux.org/alpine/v3.14/community]
OK: 14935 distinct packages available
(1/5) Installing ca-certificates (20191127-r5)
(2/5) Installing brotli-libs (1.0.9-r5)
(3/5) Installing nghttp2-libs (1.43.0-r0)
(4/5) Installing libcurl (7.78.0-r0)
(5/5) Installing curl (7.78.0-r0)
Executing busybox-1.33.1-r3.trigger
Executing ca-certificates-20191127-r5.trigger
OK: 8 MiB in 19 packages

]]> Q2. What is the difference between docker stop and docker kill? https://www.bestdevops.com/q2-what-is-the-difference-between-docker-stop-and-docker-kill-2/ Mon, 30 Aug 2021 07:43:43 +0000 https://www.bestdevops.com/?p=19984 One can stop and kill a running container. Docker stop will only stop the container gracefully. Docker kill will immediately kills all the process. There is a difference in exit code.. 

root@ip-172-31-28-155:/home/ubuntu# docker stop rajuc
rajuc
root@ip-172-31-28-155:/home/ubuntu# docker ps -a | grep rajuc
548886386f8b   httpd          "httpd-foreground"       30 minutes ago      Exited (0) 7 seconds ago                rajuc


root@ip-172-31-28-155:/home/ubuntu# docker kill rajuc
rajuc
root@ip-172-31-28-155:/home/ubuntu# docker ps -a | grep rajuc
548886386f8b   httpd          "httpd-foreground"       31 minutes ago      Exited (137) 8 seconds ago              rajuc
]]> What is the difference between docker pause and docker unpause? https://www.bestdevops.com/what-is-the-difference-between-docker-pause-and-docker-unpause-2/ Mon, 30 Aug 2021 07:29:50 +0000 https://www.bestdevops.com/?p=19922 Docker pause suspends all the process to container. Docker unpause will un-suspend all the process to container

root@ip-172-31-28-155:/home/ubuntu# docker pause rajuc
rajuc
root@ip-172-31-28-155:/home/ubuntu# docker ps | grep rajc
root@ip-172-31-28-155:/home/ubuntu# docker ps | grep rajuc
548886386f8b   httpd     "httpd-foreground"       20 minutes ago      Up 20 seconds (Paused)   80/tcp    rajuc

unpause

root@ip-172-31-28-155:/home/ubuntu# docker unpause rajuc
rajuc
root@ip-172-31-28-155:/home/ubuntu# docker ps | grep rajuc
548886386f8b   httpd     "httpd-foreground"       21 minutes ago      Up 50 seconds            80/tcp    rajuc
]]> Question 1: What is docker container with image? https://www.bestdevops.com/question-1-what-is-docker-container-with-image/ Mon, 30 Aug 2021 07:21:45 +0000 https://www.bestdevops.com/?p=19868 –

Inside a container all the necessary files/libraries/code to execute a program will be present.

  • Running instance of image is called container
    • Created a container
    • started a container
    • stopped a container

docker create --name rajuc httpd
548886386f8b3e430db0957ee104b53f004fd67f55044252d6566c5d3f25f926

docker ps | grep rajuc
548886386f8b   httpd     "httpd-foreground"   4 minutes ago        Up 14 seconds            80/tcp    rajuc

root@ip-172-31-28-155:/home/ubuntu# docker stop rajuc
rajuc
root@ip-172-31-28-155:/home/ubuntu# docker ps | grep rajuc
root@ip-172-31-28-155:/home/ubuntu# docker ps -a | grep rajuc
548886386f8b   httpd          "httpd-foreground"       12 minutes ago       Exited (0) 22 seconds ago                   rajuc

]]>