Install Docker on Linux

 

Docker

On your Linux machine (I'm using Ubuntu), check if you have docker installed by issuing the following command

docker --version

On my machine I did not find one, so we will go ahead and install the docker
Update the apt package index. Issue

sudo apt-get update

Install packages for apt to use a repository

sudo apt-get install \
apt-transport-https \
ca-certificates \
curl \
gnupg-agent \
software-properties-common

Add Docker's GPG Key

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

Setup the stable command using the following command

sudo add-apt-repository \
"deb [arch=amd64] https://download.docker.com/linux/ubuntu \
$(lsb_release -cs) \
stable"

Install Docker

sudo apt-get update

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

Once the Installation is complete, check the docker version

docker --version

Run Hello-world image by issuing following docker command

docker run hello-world

Run docker ps command to list the containers

Docker Commands

 

Docker Learning

Run an image: docker run hello-world

Check the Images running: docker ps

docker ps -all and docker ps --all

Create and start start an image
docker create busybox ping google.com

docker start 3b8cf24b0ed8b69554004ead964263cce5578800c85f71f4ad8376dd3368ef57

docker start -a 3b8cf24b0ed8b69554004ead964263cce5578800c85f71f4ad8376dd3368ef57

docker logs command

docker start 3b8cf24b0ed8b69554004ead964263cce5578800c85f71f4ad8376dd3368ef57

docker logs 3b8cf24b0ed8b69554004ead964263cce5578800c85f71f4ad8376dd3368ef57

Stop a container

docker ps

docker stop 3b8cf24b0ed8

docker kill 0cb4c057cb15

Start a stopped container

Create and run a redis server using

docker run redis and then do ctrl +c, exit. check the stopped processes or containers. Lets start a stopped redis server using the container id

Connect to redis server using redis-cli to a particular container using exec command

root@yashwanthsn-VirtualBox:~# redis-cli
Could not connect to Redis at 127.0.0.1:6379: Connection refused
not connected>

root@yashwanthsn-VirtualBox:~# docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
8f722cf5fd6f redis "docker-entrypoint.s…" 4 minutes ago Up 4 minutes 6379/tcp eloquent_saha

root@yashwanthsn-VirtualBox:~# docker exec -it 8f722cf5fd6f redis-cli
127.0.0.1:6379> set value 5
OK
127.0.0.1:6379> get value
"5"

Remove all stopped containers

docker system prune

Docker Shell

root@yashwanthsn-VirtualBox:~# docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
7240a893ecdd redis "docker-entrypoint.s…" 18 seconds ago Up 15 seconds 6379/tcp nifty_wing

root@yashwanthsn-VirtualBox:~# docker exec -it 7240a893ecdd sh
/ # ls
echo :Hello, World"
Hello, World

root@yashwanthsn-VirtualBox:~# docker run -it busybox sh
/ # ls
bin dev etc home proc root sys tmp usr var
/ # ping google.com
PING google.com (172.217.160.206): 56 data bytes
64 bytes from 172.217.160.206: seq=0 ttl=114 time=69.558 ms
64 bytes from 172.217.160.206: seq=1 ttl=114 time=64.513 ms
^C
--- google.com ping statistics ---
2 packets transmitted, 2 packets received, 0% packet loss
round-trip min/avg/max = 64.513/67.035/69.558 ms
/ #

Creating Docker Images and Dockerfile

 

Dockerfile

Create a directory called redi-image

mkdir redis-image
cd redis-image

Create a Docker file "Dockerfile" inside the redis-image directory. The Dockerfile has below content

From the base image

Run the update on redis

Command

Next build the image using the following docker command

docker build .

Now run the docker run command

docker run 2cad9caf152f

Redis server is up and ready to accept connections

Open a new terminal and run docker ps

Connect to redis-cli using the redis-server container and run commands