DEV Community: Pranjal-Agrawal

Docker Port Expose

Pranjal-Agrawal — Wed, 13 Jul 2022 08:51:46 +0000

Hi Readers, Docker is an open source platform adopted widely to ease the developing, shipping, and running applications. Docker has a object named containers isolates the applications from the infrastructure and avoids any external affect on the development environment.

In this blog we will see some network part of containers.

We will see how to enable communication of the container to the outside world or to the other containers.

We do this by exposing ports and mapping these ports.

Let’s see how we can do that.

ssh into the instance

Run these commands

sudo su
yum update -y

Install the Docker

yum install docker -y

Start the Docker service

service docker start

Now our base machine is ready.
We will create a server named as demoserver with port(publish) 80 expose map the host port no 80 with container port no 80.

docker run -td --name demoserver -p 80:80 ubuntu

Check the running containers.

docker ps

To get the details of the port we have exposed.

docker port demoserver

Execute the container and go inside the container by starting a new process.

docker exec -it demoserver /bin/bash
apt-get update

apt-get install apache2 -y

Then move to this path and create an index.html file

cd /var/www/html
echo "HELLO WORLD">index.html

Now start the apache2 service

service apache2 start

Copy the public IP of the instance

And run on the browser now

The contents of the index file is now visible.

Docker Volume and how to share it.

Pranjal-Agrawal — Tue, 12 Jul 2022 10:12:58 +0000

Docker is a common containerization solution that offers a user-friendly interface. It allows you to deploy your application as a lightweight process set rather than a complete virtual machine.

Docker Volume:-

A Docker volume is an independent file system entirely managed by Docker and exists as a normal file or directory on the host, where data is persisted.

Volume is simply a directory made inside our container.
Even if we stop the container still we can access volume.
We can declare a directory as a volume only while creating container.
Cannot create volume for existing container.
Can share the volume across any number of containers.

Benefits of Volume:-

Decoupling container from storage.
Share it among different containers.
On deleting the container the volume does not get deleted.

We can map volume in two ways:-

Container <-> Container
Host <-> Container

Created an EC2 Instance-

Then ssh into the instance-

CREATING VOLUME FROM DOCKER FILE AND MAPPING IT TO ANOTHER CONTAINER:-

sudo su

yum update -y

Install the Docker:-

yum install docker -y

Create a Docker file:-

vi Dockerfile

Write the following inside the Dockerfile

Then create the image from this Dockefile:-

Now create a container with the name cont1 from the image and run:-

Create some files in it:-

Now to share the volume with another container, create a container with a name cont2:-

After creating the cont2, the volume from cont1 would be visible and any changes made in that volume will be visible to both the containers.

_CREATING THE VOLUME USING COMMAND:-
_
Create a new container with name cont3

Create a new container with the name cont4 and share the volume with it.

Create some files inside it and see its present in both the containers.

SHARING VOLUME HOST <-> CONTAINER:-

Verify the files in the /home/ec2-user and run the following command -

Go to that directory and do ls

Create some files in the container in that particular directory

Now check in the EC2 host machine and we can see the files we created now.

Docker Swarm in AWS (set up)

Pranjal-Agrawal — Sun, 29 May 2022 11:22:17 +0000

What is a Swarm?
Docker Swarm is a cluster management and orchestration tool that makes it easy to scale and manage your already existing docker services. A swarm consists of multiple Docker hosts that run in the so-called swarm mode and act as managers (managing member relationships) or as workers (run the services). A given Docker host can be a manager, worker or can perform both roles.
When creating a service in a swarm you define the optimal state of your service (number of replicas, ports of the service, network and storage resources, and more). Docker will try to maintain this desired state by restarting/rescheduling unavailable tasks and balancing the load between different nodes.
Managers Nodes:
Manager nodes distribute and schedule incoming tasks onto the Worker nodes, maintain the cluster state and perform orchestration and cluster management functions. Manager Nodes can also optionally run services for Worker nodes.
Worker Nodes:
Worker nodes are also instances of the Docker Engine whose sole purpose is to execute containers and services as instructed by the Manager Nodes.

Steps To Host A Website In Docker Container And Managing It Using Docker Swarm.

Launch 4 Ec2 instances with tags as Master, Worker-1 , Worker-2,Worker-3.

Connect To Servers using the Xshell and initialize Docker.
Command yum install docker* -y
Command to start docker is- systemctl start docker
Command to enable docker is :- systemctl enable docker

Initialize Docker Swarm into your instances.
Command to initialize docker Swarm :- docker swarm init

Now, a token will be shown . Copy this token and paste it in the other nodes. Now the other nodes will become the Worker nodes.

You can check the joining status of the nodes by using the command docker node ls in the Master Node.

write the docker file to carry out the following functions. And Docker file should written into the VI Editor.

Copy and run the same Docker file into the worker node's as it will be helpful in building the image of the same Docker Container into the worker node's also.
Save the docker file into the VI Editor and run the following to command to build the image of the docker container into the master node.

Build the image by command -
docker image build -t appimage:1 .
You can check the image by using the command -
docker image ls

Now, you have to run the services from the Master Node command docker service create --name #name_of_the_service -p 80:80 #any_name_of_image:1

Check the service id using command docker service ls .
Note this service ID.
Create the containers using command: docker service scale #service_id = 4(you can give any number of container).
The containers are randomly deployed on any one the Master or Worker nodes.
Docker Swarm also provides the Load Balancing features thus providing maximum availability.

Finally, your docker swarm is configured and ready.
When you hit the IP of any worker or the master node, you will be able to view your site mapped.

(This is the sample site I have downloaded from internet and httpd into my EC2 master instance).

Complete OpenVPN setup in AWS

Pranjal-Agrawal — Sun, 22 May 2022 07:14:50 +0000

Accessing your public EC2 instances using SSH and encrypting is fine. But what about working with AWS-based data that’s not public? There are all kinds of reasons why admins keep such resources out of reach of the general public. But if you can’t get at them when you need, what good are they likely to do you?

The OpenVPN Access Server
As the name suggests, OpenVPN is an open source project, and you’re always able to download the free community edition and set things up on your own VPN server. But the OpenVPN company also provides an OpenVPN Access Server as an EC2 AMI .

What does it cost?
If you’re only testing things out and don’t plan to access the VPN using more than two connections at a time, then the AMI itself is free.

First of all we are deploying a Linux AMI instance with disabled Auto-assign Public IP.

We will be unable to ssh into it as it has no public IP assigned (as shown in the picture below).

Launching an OpenVPN Access Server

OpenVPN Access Server AMIs available from the AWS Marketplace.

When it comes to instance type, We can keep it within the free tier.

Choose a subnet and note for later

Now the Security Group page is where the OpenVPN AMI settings really shine. We’re presented with a security group that opens up everything we’ll need.

Note: If practical, it would normally be a good idea to tighten those rules so only requests from valid company IP address ranges are accepted, but this will be fine for short-term testing.

Then, press Enter to all the default requirements.

Note the Admin UI and Client UI.

Accessing the server
Paste the public IP address into the terminal as part of SSH command that calls the key pair set for this instance.
ssh -i KeyPairName.pem openvpnas@

We will need to give the openvpn user a password so We can use it to log into the web GUI.
We do that as sudo with the passwd command.
sudo passwd openvpn

Now We are going to use a browser to log into the web GUI. We use our server’s public IP address with the secure https prefix, followed by slash and admin.
https:///admin

Provide the username and password as set earlier.

Provide the username and password and connect .

And then ssh to Linux instance and it will responded successfully.