Setting up Docker engine on Ubuntu server on Azure VM

First go to Azure portal and create ubuntu 18.4 version VM.

Open the Azure VM and note the IP address and connect to the server using putty

Installing Docker on Linux

 

 Prerequisite

    1.   64 bit version of Ubuntu

    2.  Network Connected

    3.  Uninstall Docker

    4.  Make modifications to the Linux package installer (apt) to add docker repository

    5.  Update Package

    6.  Install Docker

     7. Verify

Ist step Uninstall Docker

   sudo apt-get remove docker docker-engine docker-ce docker.io

2^nd step Update Packages and Allow Apt to Use a Repository over HTTPS

    sudo apt-get update

and

  sudo apt-get install \

  apt-transport-https \

 ca-certificates \

curl \

software-properties-common

3^rd Step Add the Docker official GPG key to Apt

   curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add

4^th Step Verify That you now have the Docker GPG Key

   sudo apt-key fingerprint 0EBFCD88

output:-

admina@ubuntuserver01:~$ sudo apt-key fingerprint 0EBFCD88

pub   rsa4096 2017-02-22 [SCEA]

      9DC8 5822 9FC7 DD38 854A  E2D8 8D81 803C 0EBF CD88

uid           [ unknown] Docker Release (CE deb) <docker@docker.com>

sub   rsa4096 2017-02-22 [S]

Here  we get the official response from Docker. We can see the UID of the Docker release. Everything looks good.

5th Add the Docker Repository to Apt

sudo add-apt-repository \

  "deb [arch=amd64] https://download.docker.com/linux/ubuntu \

 $(lsb_release -cs) \

 stable"

And with that repository added, we're going to do an apt-get update again to download the latest package index now that we have the Docker repository added to our list of repositories. run again, apt-get update.

6^th Re-Update the Apt Package Index

   sudo apt-get  update

7th To install a specific version of Docker Engine, list the available versions in the repo, then select and install:

   apt-cache madison docker-ce

set desired version below and execute below command (sudo apt-get install docker-ce=18.03.1~ce~3-0~ubuntu

)

If you didn't want to specify a specific version and just get the latest stable version, you could just do an apt-get install docker-ce. I have added on the equals here to specify the specific version of Docker CE for Ubuntu that we'd like to run.

 8^th Install a Specific Version of Docker

   sudo apt-get install docker-ce=18.03.1~ce~3-0~ubuntu

 Verify that Docker Engine is installed correctly by running the hello-world image but before verification Add Groups and Users

 9^th Add Groups and Users

     sudo groupadd docker

    sudo usermod -aG docker $USER

   *Log out and log back in for this to take effect

 10^th  Verify Docker Is Installed

    docker version

    docker run hello-world

output

admina@ubuntuserver01:~$ docker version

Client:

 Version:      18.03.1-ce

 API version:  1.37

 Go version:   go1.9.5

 Git commit:   9ee9f40

 Built:        Wed Jun 20 21:43:51 2018

 OS/Arch:      linux/amd64

 Experimental: false

 Orchestrator: swarm

Server:

 Engine:

  Version:      18.03.1-ce

  API version:  1.37 (minimum version 1.12)

  Go version:   go1.9.5

  Git commit:   9ee9f40

  Built:        Wed Jun 20 21:42:00 2018

  OS/Arch:      linux/amd64

  Experimental: false

admina@ubuntuserver01:~$ docker run hello-world

if you do not want to do all these 

https://github.com/Azure/azure-quickstart-templates/tree/master/docker-simple-on-ubuntu

Docker Architecture

The Docker Engine is designed as a client server application and it's really made up of three different things.

 It starts off with dockerd or the Docker daemon which is installed when you install Docker and that's the server, that's the Docker server itself. 

 Along with the installation of the Docker Engine, you receive a RESTful API which is important because that defines the interface that all other programs

 use to talk to the daemon and there's so many different pieces that make up the typical Docker ecosystem, 

 both tools from Docker as well as third-party tools. 

 And then finally, you have the Docker client.

 So, this is the actual Docker command that you run as a client to talk to the Docker server, to pull down images, build images and instantiate containers.

 No matter what version of Docker you're using whether it's the Community Edition or the Enterprise Edition 

 the Docker Engine is the required foundation that makes it all possible.

 Now let's review the typical Docker architecture. 

 The Docker daemon is installed on the Docker host.

 That Docker host could be your desktop or laptop computer, 

 it could be a server in the data center or it could be a virtual machine running up in the cloud.

 From there, the Docker host is used to execute or instantiate your containers and images. 

 It's administered through the Docker client which could be on the same host as the Docker daemon or it could be remote.

 That's the beauty of the Docker client server architecture. 

 Using the Docker client you can pull down images from a registry and then execute those images as containers running on the Docker host.

Docker NameSpace

The Docker engine utilizes something called 'Namespaces' to isolate what's happening in the running containers

 from the operating system that those containers are running on. With Namespaces the kernal resources such as the process ID, 

 user IDs, network storage, and inner process communications or IPC, 

 can all be virtualized and shared between the host operating system and the containers running on top.

 Namespaces weren't created by Docker. 

 Linux Namespaces are a core feature of the Linux kernal and have been around since 2002. Since that time there's been a lot of enhancement around 

 Namespaces and Docker has capitalized on those enhancements in the Docker engine. 

 Docker utilizes process, mount, IPC, network, and user Namespaces 

 to isolate what's happening on the Docker host from what's happening in the Docker containers. 

 Thankfully, Microsoft has even added the equivalent of Namespace isolation in Windows so that Docker for Windows could provide the same functionality.

 Namespaces are similar in concept to what a hypervisor does to provide the virtual resources like virtual CPU,

 virtual memory and virtual storage to a virtual machine.

 Namespaces keep containers isolated until Docker administrators.

 for example, allow containers to communicate over the Docker virtual networks on the same host. 

 With the Namespace isolation in Docker operating systems and applications running in containers feel like they have their own process trees,

 file systems, network connections, and more.

 

 It's even possible in Docker to map a user account in a container to a user account in the host operating system.

 Here's a simple example of how Namespace isolation works. 

 For example, here I am in an Ubuntu Docker host, and if I do a ps -ef you can see there are roughly a hundred different processes running on this host. 

 If I do the ip addr command or ip address it'll list out the ip addresses. 

 You can there's roughly some 70 different network interfaces on this host.

 docker run -it alpine /bin/sh

 However if I do a  docker run -it alpine /bin/sh

 

 we pull down an alpine Linux image, we're running that as a container, 

 and now if I perform the same commands here, for example ps -ef, 

 we have exactly two processes. 

 So what's happening in this operating system in the container is isolated off the process isolation.

 Using Namespaces is isolating us off from what's happening in the Docker host and vice versa. 

 Another example here is if I run the ip addr command, you can see we have exactly two interfaces, 

 with two different ip addresses on those interfaces.

 Again, another example of how Namespaces work to isolate off network resources from the Docker host. 

 So that's how Namespaces work in Docker.