How to use docker

1. Prologue

1.1 Why I output this document

When ourtest has dependencies with the environment, how to get rid of the issue whichcaused by these dependency issue after you change to another test environment,i.e., we test it on Ubuntu16.04 and our customer use Ubuntu22.04?

I think Docker could work for you in a performance-intensive and low overhead approach. It is a very good & popular tool for us to make the develop/deploy environmentportable, and many people don’t get familiar of it, much less get the hang of it.

1.2 Who will be the reader of this document

Any people who will develop or deploythe software on Linux system that have the specific requirement of theenvironment configuration, you need to learn it to make the environmentconfigurations portable.

2. What's docker

2.1 Introduction

Docker is a tool that allows developers, sys-admins etc. To deploy their applications easily in a sandbox (calleds) to run on the host operating system i.e., Linux. The key benefit of Docker is that it allows users to package an application with all its dependencies into a standardized unit for software development. Unlike virtual machines,s do not have high overhead and hence enable more efficient usage of the underlying system and resources.Find the difference between Virtual Machine VS Docker from the link below:
https://cloudacademy.com/blog/docker-vs-virtual-machines-differences-you-should-know/
https://www.freecodecamp.org/news/a-beginner-friendly-introduction-to-containers-vms-and-docker-79a9e3e119b/

Virtual Machine VS Docker

2.2 Docker Image and Container

Docker images are stored as a series of read-only layers:

docker image layers

When a is started, Docker adds a read-write layer on top of the read-only layers/images:

docker layers

3. Get started to learn the basic operation of Docker

3.1 How to install Docker on Ubuntu16.04

3.1.1 Install relevant package to access apt software package via https：

• sudo apt-get update
• sudo apt-get install apt-transport-https ca-certificates curl software-properties-common

3.1.2 Prepare Docker GPG private-key to verify the integrity of the downloaded Docker package.

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

3.1.3 Add the Docket APT package download link source：

• echo “deb [arch=amd64 signed-by=/usr/share/keyrings/docker-archive-keyring.gpg] https://download.docker.com/linux/ubuntu xenial stable” | sudo tee /etc/apt/sources.list.d/docker.list > /dev/null

3.1.4 Update apt source and intall Docker:

• sudo apt-get update
• sudo apt-get install docker-ce

3.1.5 Check Docker version

• sudo docker version

  
  
  

  Install docker on Ubuntu16.04

3.2 How to create & manage docker image

3.2.1 Pull image manually
pull the base image file from docker hub repository with command [docker pull ubuntu] and check if the image pull down successfully via [docker images] to check the current images we have.

pull docker image

3.2.2 Build with dockerfile

build image via docker file_1

build image via docker file_2

• Note: we could find that the difference between docker pull & docker build, docker build creates multiple images, the final one based on original image specified in 'From' parameters, and integrates the tools we want with apt-get install command in 'RUN' parameters.

3.3 How to create & mange

3.3.1 docker create & docker start
we could create docker via docker create and start&enter via 'docker start' like the picture shows below

docker create & docker start

3.3.2 docker run
We could also use [docker run] to create&start&enter the like the picture shows below

docker run

3.4 Install tool in docker:

install tools

3.5 How to commit the modification in to a new image

commit the modification

3.6 How to save image to a file or load image from file

save/load docker image

3.7 How to export to a file and import it as an image

export/import

We could find that, docker save command can't save the to file, but docker export command can do that, the file created by [docker export] command could import to docker via docker import command and the import result will be convert the to an image file.

3.8 How to remove docker

• sudo apt-get autoremove docker docker-ce* docker-engine docker.iod runc
  

  

• check if the install package is still there via dpkg -l | grep docker, if yes, we could remove the install package via dpkg -l | grep ^rc | awk '{print }' | sudo xargs dpkg -P
  

  

4. Appendix

4.1 Docker Command

N.o	Command	Description
1	docker build	Build an image from a Dockerfile.
2	docker images	Show the image information on the docker.
3	docker ps	Show the information on the docker.
4	docker run	Create & start a new with the command you want to run.
5	docker start	Start one or more stoppeds, -I will attach STDIN.
6	docker stop	Stop one or more runnings.
7	docker commit	Create a new image from a's changes.
8	docker rmRemove one or mores.
9	docker rmi	Remove one or more images.
10	docker export	Export a's filesystem as a tar archive.
11	docker import	Import the contents from a tarball to create a filesystem image.
12	docker save	Save one or more images to a tar archive (streamed to STDOUT by default).
13	docker load	Load an image from a tar archive or STDIN.
14	docker pull	Pull an image or a repository from a registry.

4.2 Reference Link

N.o	TopicReference	Link
1	Official website	https://hub.docker.com/
2	Documentations of Docker	https://docs.docker.com/get-started/overview/
3	Install docker on Ubuntu	ttps://blog.csdn.net/weixin_42178777/article/details/131741720