Learning About Docker

Playlist by Learn Linux TV

What is Docker:

Installing Docker: GNU/Linux:

1. Install

$ sudo apt update && sudo apt upgrade
$ sudo apt install docker.io

2. System Check

$ systemctl status docker

Output

● docker.service - Docker Application Container Engine
     Loaded: loaded (/lib/systemd/system/docker.service; enabled; vendor preset: enabled)
     Active: active (running) since Fri 2023-09-01 07:13:06 IST; 2min 26s ago
TriggeredBy: ● docker.socket
       Docs: https://docs.docker.com
   Main PID: 2468 (dockerd)

If it says disabled in Loaded section

$ systemctl enable docker

This will enable docker to run on startup.

3. Docker Check

$ sudo docker run hello-world

4. Permission Issues

Run

$ docker images

If you are getting Permission Denied error

$ sudo usermod -aG docker yourusername && reboot

Rebooting because logging out and in did not help.

Now run

$ docker images

Image is the blueprint for container.

Docker Commands:

For searching images:

$ docker search image-name

Downloading Images:

$ docker pull image-name

Running a container - 1:

$ docker run image-name

If the image has nothing to do, docker will stop it.

List of running Containers

$ docker ps

For all

$ docker ps -a

Running a container - 2:

$ docker run -it ubuntu /bin/bash

-t              : Allocate a pseudo-tty
-i              : Keep STDIN open even if not attached
-d              : Detached, for running container in background
-p              : Ports (host:container)

This will run the Ubuntu container and open bash shell into the container. You may use it normally and install applications. But after you have logged out of the container all the data will be gone. This is sort of a temporary container.

Container by default don’t save changes.

Attach detached container:

$ docker attach container-name/id

Keep the container state:

Inside the container press

CTRL + p + q

This will exit from container but the container will run in background.

Docker Image Creation:

$ docker commit container-id new-container-name:tag-name