Introduction

Docker is an open-source containerization platform that developers use to build, run, and package applications for deployment using containers. Unlike virtual machines, Docker containers offer: OS-level abstraction with optimum resource utilization. Interoperability

Prerequisites

Ubuntu with 20.04 or WSL environment
Nothing else 😀

Althought this guide is for Ubuntu 20.04 and WSL , it should work for all other version of Ubuntu also.

Installing Docker

First, we need to uninstall the older version of docker.

Uninstalling Docker

sudo apt-get remove docker docker-engine docker.io containerd runc

It's ok if you get output like below.

Reading package lists... Done
Building dependency tree
Reading state information... Done
E: Unable to locate package docker-engine

Installing Methods

There are many ways to install docker, but we are going to use the recommended repository method.

Set up repository

Update apt package and install necessary tools

sudo apt-get update
sudo apt-get install  ca-certificates  curl  gnupg  lsb-release

Add Docker’s official GPG key

curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo gpg --dearmor -o /usr/share/keyrings/docker-archive-keyring.gpg

Add docker repository

echo \
"deb [arch=$(dpkg --print-architecture) signed-by=/usr/share/keyrings/docker-archive-keyring.gpg] https://download.docker.com/linux/ubuntu \
$(lsb_release -cs) stable" | sudo tee /etc/apt/sources.list.d/docker.list > /dev/null

Install Docker engine

Update apt package and install docker engine

sudo apt-get update
sudo apt-get install docker-ce docker-ce-cli containerd.io

Start Docker service
```
sudo service docker start
```

Verify if Docker is installed correctly
```
sudo docker run hello-world
```
If you get something like Hello from Docker! This message shows that your installation appears to be working correctly. that's mean you have installed docker.

Notice how you have to run docker with sudo command. It is not recommended running docker with sudo. To run docker without sudo we will add our current user to docker group, that way we can run docker without sudo

To create the docker group and add your user:

Create the docker group.
```
sudo groupadd docker
```
Add your user to the docker group.
```
sudo usermod -aG docker $USER
```
Now log out and log in again and try to run hello-world image without sudo.

Installing docker-compose

We will download docker-compose from repository and manually installing it.

sudo curl -L "https://github.com/docker/compose/releases/download/v2.1.1/docker-compose-$(uname -s)-$(uname -m)" -o /usr/local/bin/docker-compose

At the time of writing docker-compose v2.1.1 is latest. You can check latest version and modify above command.

https://github.com/docker/compose/releases/latest

Add appropriate execution permission to docker compose
```
sudo chmod +x /usr/local/bin/docker-compose
```
Verify docker-compose installation
```
docker-compose version
```

Deploying sample service

We will be deploying containous/whoami container with docker and docker-compose for testing

Deploying using docker

Run below command to deploy containous/whoami container

docker run -d -p 8080:80 --name whoami containous/whoami

Now check if our container is running
```
docker ps
```
If you get something like below image then you are on right path

Now we will send api request to this container

curl  localhost:8080/api

You should get something like this

{"hostname":"b1b7e7b79c89","ip":["127.0.0.1","172.17.0.2"],"headers":{"Accept":["*/*"],"User-Agent":["curl/7.68.0"]},"url":"/api","host":"localhost:8080","method":"GET"}

Let's remove this container. First get your container id using docker ps command.
```
docker stop b1b7e7b79c89
docker rm b1b7e7b79c89
```
Change b1b7e7b79c89 with your container ID.

Deploying using docker-compose

Now we will deploy same container using docker-compose.

Create docker-compose.yaml
```
touch docker-compose.yaml
```

edit docker-compose.yaml

nano docker-compose.yaml

Now paste below content

version: "3.3"
services:
whoami:
  image: "containous/whoami"
  container_name: "whoami"
  ports:
   - 8080:80

Now run docker-compose
```
docker-compose up -d
```
Verify our container is running or not using docker ps
Send api request using curl
```
curl  localhost:8080/api
```
You should see a reply similar to above. This means our container is running correctly.
Stop container.
```
docker-compose down
```

That's it, you have successfully installed Docker and docker-compose 🎊💐

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