collection of containers

Replication Controller

Storage Management

Resource Monitoring

Health Checking

Networking

Helm Charts

POD Distrubution

Cluster Federation

How kubernates works?

Kubernetes supports several base container engines, and Docker is just one of them. The two technologies work great together, since Docker containers are an efficient way to distribute packaged applications, and Kubernetes is designed to coordinate and schedule those applications.

What are the components in master?

API Server

Scheduler

Controller Manager

etcd

Kubelet

Kube-proxy

What are the component of workers?

A Kubernetes cluster consists of a set of worker machines, called nodes, that run containerized applications. Every cluster has at least one worker node

• kubelet
• kube-proxy
• and PODS. Each POD can have multiple containers as required

Components of Workstation

• kubectl
• creation of json/yaml file

POD?

Pods are the smallest, most basic deployable objects in Kubernetes. A Pod represents a single instance of a running process in your cluster.

Pods contain one or more containers, such as Docker containers. When a Pod runs multiple containers, the containers are managed as a single entity and share the Pod’s resources. Generally, running multiple containers in a single Pod is an advanced use case.

• Pods represent the processes running on a cluster. By limiting pods to a single process, Kubernetes can report on the health of each process running in the cluster
• a unique IP address (which allows them to communicate with each other)
• persistent storage volumes
• configuration information that determine how a container should run
• Pods are created by workload resources called controllers, which manage rollout, replication, and health of pods in the cluster. For example, if a node in the cluster fails, a controller detects that the pods on that node are unresponsive and creates replacement pod(s) on other nodes
• Although most pods contain a single container, many will have a few containers that work closely together to execute a desired function.
• Pods are almost always created by controllers which then can automatically manage the pod lifecycle, including replacing failed pods, replicating pods when necessary, and evicting the pod from cluster nodes when they are complete or no longer needed

[root@localhost ~]# history
1 ifconfig
2 sudo yum install -y yum-utils device-mapper-persistent-data lvm
3 udo yum-config-manager –add-repo https://download.docker.com/linux/centos/docker-ce.repo
4 sudo yum-config-manager –add-repo https://download.docker.com/linux/centos/docker-ce.repo
5 sudo yum install –y https://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.r
6 sudo yum-config-manager –enable rhui-REGION-rhel-server-extras
7 sudo yum install -y docker-ce
8 sudo yum install docker-ce
9 docker -v
10 – Enable Docker
11 Start Docker
12 Start Docker
13 start docker
14 sudo systemctl enable docker
15 sudo systemctl start docker
16 history

Verification.

root@720751c45f2c:/# ps -eaf | grep dockerd
root 3672 1 0 13:38 pts/0 00:00:00 grep –color=auto dockerd

[root@localhost ~]# which containerd
/bin/containerd

[root@localhost ~]# ps -eaf | grep containerd
root 3110 3032 0 02:41 pts/1 00:00:00 grep –color=auto containerd
root 30400 1 0 01:36 ? 00:00:00 /usr/bin/containerd
root 30409 1 0 01:36 ? 00:00:04 /usr/bin/dockerd -H fd:// –containerd=/run/containerd/containerd.sock

Assignment#1

[root@localhost ~]# docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
720751c45f2c ubuntu “bash” 46 minutes ago Exited (1) 4 minutes ago dazzling_aryabhata
684695c21d76 ubuntu “bash” About an hour ago Exited (0) About an hour ago happy_kepler

[root@localhost ~]# docker run -itd ubuntu
cb56e4630dfba75663fd09174bf1d2d555b0258a6197bdf50c7ae2173d2d5ff4
[root@localhost ~]# docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
cb56e4630dfb ubuntu “bash” 15 seconds ago Up 14 seconds eloquent_hopper
720751c45f2c ubuntu “bash” 46 minutes ago Exited (1) 5 minutes ago dazzling_aryabhata
684695c21d76 ubuntu “bash” About an hour ago Exited (0) About an hour ago happy_keple

[root@localhost ~]# ^C
[root@localhost ~]# docker pull httpd
Using default tag: latest
latest: Pulling from library/httpd
b4d181a07f80: Pull complete
4b72f5187e6e: Pull complete
12b2c44d04b2: Pull complete
35c238b46d30: Pull complete

[root@localhost ~]# docker images|grep httpd
httpd latest bd29370f84ea 12 days ago 138MB

[root@localhost ~]# docker attach cb56e4630dfb
root@cb56e4630dfb:/#

[root@localhost ~]#git version

git version 2.25.1

Create an image with base – centos and git must be inst

[root@localhost ~]# cat dockerfile
[root@localhost ~]# vi dockerfile
[root@localhost ~]# cat dockerfile

M ubuntu
MAINTAINER Nagendra
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 /usr/sbin/apache2ctl -D FOREGROUND

[root@localhost ~]# docker images
REPOSITORY   TAG       IMAGE ID       CREATED          SIZE
ub-up-git    latest    14ca71c606d1   28 seconds ago   259MB
ubuntu       latest    c29284518f49   7 days ago       72.8MB
httpd        latest    bd29370f84ea   12 days ago      138MB

Push a docker image to hub.docker.com

[root@localhost ~]# docker tag ub-up-git nag9779/nagendra01
[root@localhost ~]# docker images
REPOSITORY           TAG       IMAGE ID       CREATED         SIZE
ub-up-git            latest    14ca71c606d1   5 minutes ago   259MB
nag9779/nagendra01   latest    14ca71c606d1   5 minutes ago   259MB
ubuntu               latest    c29284518f49   7 days ago      72.8MB
httpd                latest    bd29370f84ea   12 days ago     138MB
[root@localhost ~]# docker login
Login with your Docker ID to push and pull images from Docker Hub. If you don't have a Docker ID, head over to https://hub.docker.com to create one.
Username: nag9779
Password:
WARNING! Your password will be stored unencrypted in /root/.docker/config.json.
Configure a credential helper to remove this warning. See
https://docs.docker.com/engine/reference/commandline/login/#credentials-store

Login Succeeded
[root@localhost ~]#