wikibackup/Docker.md

title	description	published	date	tags	editor	dateCreated
Docker		true	2024-07-26T10:03:09.866Z		markdown	2024-07-26T10:03:03.792Z

Docker Overview

Docker is a tool for containerization, enabling the sharing of development environments across various operating systems through containers. This accelerates development time and allows team members to share environments without dependency conflicts, as all dependencies are contained and isolated within the container.

History

Before the concept of containers and environment isolation, virtualization was the main solution for separating development environments from the host system. Users would allocate CPU, memory, and hard space resources to a virtual system, but this approach was not optimal because a significant amount of resources was consumed by the virtual operating system, resulting in slower processing speeds compared to the host system.

With the advent of containers, isolation and separation of different environments became more cost-effective and resource-efficient. Docker is one of the tools that can be used for building and managing containers. If you need to share your development/production environment with others, Docker facilitates this by allowing you to share your container skeleton file (image), speeding up the process. Additionally, other users don’t need to worry about resolving dependencies as they are already included in the container.

Installation and Setup

The Docker documentation provides comprehensive installation instructions for Linux systems. However, distributions based on Arch Linux are not officially supported and the installation is considered unstable.

1. Open your terminal and install Docker using the package manager:

   sudo pacman -S docker
   

   If you encounter the error docker not found, make sure to update your repositories with the command sudo pacman -Syu.

2. If you are using systemd as your init system, enable the Docker service with:

   sudo systemctl enable --now docker.service
   

3. Add your username to the Docker group:

   sudo usermod -aG docker $USER
   

   To apply the changes, either log out and log back in or use the command newgrp docker.

4. Verify the Docker installation by running the hello-world image:

   docker run hello-world
   

The run command executes images, which are blueprints for containers that consist of predefined files and configurations.

To list the images on your system, use docker images.

To list active containers, use docker ps.

Docker Hub

Docker Hub serves as Docker's default repository for downloading and uploading images.

For example, if you want to use nginx as your web server, you can download the nginx image from Docker Hub and create a container from it.

1. Log in to your Docker Hub account with:

   docker login
   

   If you don't have an account, create one here.

2. Download the latest nginx image with:

   docker pull nginx
   

   Unfortunately, Docker Hub is blocked in Iran. If you encounter a 403 error or connection timeout, it is likely due to these restrictions. Refer to the sanctions workaround to resolve this issue.

   nginx web server has comprehensive documentation on Docker Hub about working with images and containers.

After downloading the image, create a container for nginx with:

docker run --name some-nginx -p 8080:80 -v /some/content:/usr/share/nginx/html:ro -d nginx

If you are using other mirrors like focker.ir to download images, replace nginx with focker.ir/nginx.

docker run --name some-nginx -p 8080:80 -v /some/content:/usr/share/nginx/html:ro -d focker.ir/nginx

1. The --name flag assigns a name to the container, in this example, some-nginx.

2. The -v or --volume flag shares a (path on the host system) with (a path in the container).

   In this example, the path /some/content on the host system is shared with /usr/share/nginx/html in the container. For instance, if you create a file named name.txt in /some/content on the host system, you can find the same file in /usr/share/nginx/html within the container.

   The ro at the end of the volume flag, separated by :, stands for read-only. If you set it to rw, it will be read and write.

3. The -p or --port flag maps a port from the host system to a port in the container.

   In this example, port 8080 on the host system is mapped to port 80 in the container.

4. The -d flag runs the process in the background.

Sanctions Workaround

To bypass sanctions, you can use the following methods:

1. Using DNS
2. Using other mirrors
3. Using proxy client tools such as Hiddify and Nekoray.

Using Other Mirrors

The simplest method to bypass sanctions is to download images from other repositories, such as focker.ir and ArvanCloud.

ArvanCloud has published a comprehensive guide on this.

In summary, you can use the following command to download images from ArvanCloud:

docker pull docker.arvancloud.ir/<ImageName>

Similarly, for focker.ir:

docker pull focker.ir/<ImageName>

Using DNS

Several internal DNS services are available to bypass sanctions, including Shecan, 403, and Begzar.

Begzar

/etc/resolv.conf
 nameserver 185.55.226.26
 nameserver 185.55.225.25

403

/etc/resolv.conf
 nameserver 10.202.10.202
 nameserver 10.202.10.102

Shecan

/etc/resolv.conf
 nameserver 178.22.122.100
 nameserver 185.51.200.2

Docker Compose

Docker Compose is one of Docker's most powerful tools, enabling you to define configurations for multiple containers in a single YAML file. This avoids the need to repeatedly type commands in the terminal or manually write scripts. Instead, you can run all the containers with a single command.

Flags

Docker provides a set of flags:

--help

Displays usage information and commands for Docker.

-D, --debug=true|false

Enables or disables debug mode.

-H, --host=[unix:///var/run/docker.sock]

Specifies the socket address for the Docker service.

-l, --log-level=debug|info|warn|error|fatal

Sets the log level (default is info).

--tls=true|false

Specifies whether to use TLS (default is false).

--tlscacert=~/.docker/ca.pem

Ensures that the certificates are signed by the specified CA.

--tlscert=~/.docker/cert.pem

Specifies the client certificate file.

--tlskey=~/.docker/key.pem

Specifies the client key file.

--tlsverify=true|false

Enables TLS and verifies remote access.

-v, --version=true|false

Displays the current version of Docker.

Commands

Use docker --help to review the list of available commands.

run

Run a new container from an image.

docker run hello-world

exec

Execute commands in a running container.

docker exec -it my_container bash

ps

List running containers.

docker ps

build

Build a Docker image from a Dockerfile.

docker build -t my_image .

pull

Download an image from Docker Hub.

docker pull nginx

push

Upload an image to Docker Hub.

docker push focker.ir/my_image

images

List available images.

docker images

login

Log in to Docker Hub.

docker login

logout

Log out of Docker Hub.

docker logout

search

Search for images on Docker Hub.

docker search redis

version

Display the Docker version.

docker version

info

Display system-wide information.

docker info

attach

Attach to a running container.

docker attach my_container

commit

Create a new image from a container's changes.

docker commit my_container my_image

cp

Copy files between a container and the host.

docker cp my_container:/path/in/container /path/on/host

create

Create a new container.

docker create --name my_container ubuntu

diff

Inspect changes to files or directories on a container’s filesystem.

docker diff my_container

events

Get real-time events from the Docker server.

docker events

export

Export a container’s filesystem as a tar archive.

docker export my_container -o my_container.tar

history

Show the history of an image.

docker history ubuntu

import

Create an image from a tarball.

docker import my_container.tar my_image

inspect

Return low-level information on Docker objects.

docker inspect my_container

kill

Kill a running container.

docker kill my_container

load

Load an image from a tar archive.

docker load -i my_image.tar

logs

Fetch the logs of a container.

docker logs my_container

pause

Pause all processes within one or more containers.

docker pause my_container

port

List port mappings or a specific mapping for the container.

docker port my_container

rename

Rename a container.

docker rename my_container new_container_name

restart

Restart a container.

docker restart my_container

rm

Remove one or more containers.

docker rm my_container

rmi

Remove one or more images.

docker rmi my_image

save

Save one or more images to a tar archive.

docker save -o my_image.tar my_image

start

Start one or more stopped containers.

docker start my_container

stats

Display a live stream of container(s) resource usage statistics.

docker stats my_container

stop

Stop one or more running containers.

docker stop my_container

tag

Create a tag for an image.

docker tag my_image my_repo/my_image:tag

top

Display the running processes of a container.

docker top my_container

unpause

Unpause all processes within one or more containers.

docker unpause my_container

update

Update configuration of one or more containers.

docker update --cpus=2 my_container

wait

Block until one or more containers stop, then print their exit codes.

docker wait my_container