Friday, September 14, 2018

Docker Components Overview

Docker Components:

Which we will install on top of a Host Physical OS or a VM.

Core components:
core components which get installed by us.I mean, the important ones.

Docker Daemon -- Docker engine runs on top of Host machine.
Docker client -- CLI used to interact with the daemon.

Workflow components: (used in creation of containers)

Docker image:  Templates which holds the environment(Bootable fs+specific files) and your applications.
Docker container: Empty box which loads an image, Runtime instances are created from images and we can start/stop/delete them.
Docker registry: Storage location for all docker images.Public/Private repositories used to store images.
Dockerfile: Automates images construction


Docker System:
Docker commands runs on Docker client to send commands to Docker Daemon.Through DOcker registry, we download/pull the base image.Using this image we create as many containers as we want.

The creation of image process can be automated with dockerfile.
We can create a new image from existing container and commit and push them to docker registry.




How to install Docker Community Edition(CE)(both engine and client), Enterprose edition is not
free.?

Windows/OSX:
Boot2Docker is a tinyVM whcih ships with virtualbox and docker client.


Ubuntu: install-docker-ce

CentOS:
Setup the docker CE repostory

yum install -y yum-utils -> Installing dependencies of OS,like update.
yum-config-manager --add-repo htttps://download.docker.com/linux/centos/docker-ce.repo

The url used Omnibus concept
This downloads docker repo and installs it.

yum -y install docker-ce
installing docker package.

Starting daemon:
service start docker (or)
systemctl start docker

To check OS details of Linux:
cat /etc/*os*rel*

To switch to root account in Linux:
su - root

#touch dummyfile  --> will create an empty file.
echo $SHELL -> for shell details.

systemctl(or)service status docker  --> to check docker daemon running or not.
ps -ef | grep docker --> alternate option to check docker daemon running or not.


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