[Docker learning notes II] Docker installation, operation process and common commands

The previous Blog introduced in detail why Docker appeared and what problems it appeared to solve; The basic components and architecture of Docker. This Blog will learn more about how to install and uninstall Docker and what are the common operation commands. Because Docker can be installed on any physical machine, virtual machine, public cloud and private cloud, and the Tencent cloud server I purchased is already a windows system and running services, so I'd better use the virtual machine installed on my PC to operate. The virtual machine I installed is Centos7. Previously, I have two blogs detailing how to install a virtual machine cluster through VMWare: [distributed cluster construction I] virtual machine configuration (VMware+Centos7+SecureCRT+AppNode) and [Distributed Cluster Construction II] clone virtual machines and configure clusters , if necessary, you can install the virtual machine locally according to my previous steps, so you don't need to buy ECs.

Docker installation

Next, install Docker on Centos7 and use SecureCRT for virtual host control. Of course, you can also use AppNode for visual remote control.

1 Environmental preparation

First, check the kernel version of Centos7 and confirm that Docker is supported. First, open VMWARE and start a virtual machine host:

Click to open the virtual host CentOS-7-TML1:

After opening the CentOS-7-TML1 host, remote control the virtual host through SecureCRT: check the kernel version: uname -r, and you can see that the kernel version is greater than 3.10

View the system configuration: cat / etc / OS release

NAME="CentOS Linux"
VERSION="7 (Core)"
ID_LIKE="rhel fedora"
PRETTY_NAME="CentOS Linux 7 (Core)"


2. Docker installation

Visit the official website of Docker and follow the steps to install: https://docs.docker.com/

Since the operation is carried out under Linux, you can directly choose Linux system installation:

1 uninstall old version

Find the CentOS installation documentation. The first step in installing Docker is to uninstall the old version:

 sudo yum remove docker \
                  docker-client \
                  docker-client-latest \
                  docker-common \
                  docker-latest \
                  docker-latest-logrotate \
                  docker-logrotate \

Because Docker has not been installed on my computer before, I will be prompted as follows:

2 download the required installation package

Install the package of the running environment through the following command: Yum install - y Yum utils

3. Set Docker image warehouse

The default download address is foreign, and the domestic image warehouse can be used:

#Foreign address
yum-config-manager \
    --add-repo \
# Set up Alibaba cloud Docker image warehouse
yum-config-manager \
    --add-repo \

The configuration results are as follows:

4 update the yum package index

Update the yum package before installing Docker engine: yum makecache fast

5. Install Docker engine

The command to install Docker engine is as follows: Yum install Docker CE Docker CE cli containerd io:

1. If the image cannot be found during the process, use this command to clean up the yum package: yum clean all.

2. If the installation result indicates that [no secret key has been installed], follow the following steps:

  • View the system version information cat / etc / RedHat release: CentOS Linux release 7.8.2003 (Core)
  • From the open source site: http://mirrors.163.com/centos/ , find the corresponding secret key of the system and install it: rpm --import http://mirrors.163.com/centos/RPM-GPG-KEY-CentOS-7

After completing the above two steps, execute the Docker installation command again:

6 start Docker

Start Docker through the following command, check the Docker version and set the automatic startup of Docker:

systemctl start docker
# Check the current version number to see if it is started successfully
docker version
# Set startup and self startup
systemctl enable docker

The results are as follows:

7 testing the Hello world program

After installation, we can download the Hello world image for testing: docker run Hello World

View the downloaded Hello world image: docker images

3. Docker unloading

The uninstallation command of Docker is as follows:

# 1. Uninstall dependency
yum remove docker-ce docker-ce-cli containerd.io
# 2. Delete resources/ var/lib/docker is the default working path of docker
rm -rf /var/lib/docker

4. Configure Alibaba cloud image acceleration

Enter Alibaba cloud's official website and search container image service: https://cr.console.aliyun.com/cn-hangzhou/instances/mirrors

Use the following commands to configure the image. Each person has his own unique accelerator

sudo mkdir -p /etc/docker
sudo tee /etc/docker/daemon.json <<-'EOF'
  "registry-mirrors": ["https://vhfhpev9.mirror.aliyuncs.com"]
sudo systemctl daemon-reload
sudo systemctl restart docker

Just follow the above command:

Docker operation process

Refer to the previous Hello world image pulling process:

[root@192 ~]# docker run hello-world
Unable to find image 'hello-world:latest' locally
latest: Pulling from library/hello-world
2db29710123e: Pull complete 
Digest: sha256:507ecde44b8eb741278274653120c2bf793b174c06ff4eaa672b713b3263477b
Status: Downloaded newer image for hello-world:latest

Hello from Docker!
This message shows that your installation appears to be working correctly.

You can know the execution process of docker run command, start and run a hello world container.

Docker is a system with client server structure. The daemon of docker runs on the host and is accessed from the client through Socker! When Docker Server receives the docker client instruction, it will execute this instruction!

Each Docker container is like a small virtual machine, which is isolated from the host, and containers are isolated from each other. When Docker creates a new container, it does not need to reload an operating system kernel like a virtual machine, but directly use the operating system of the host, while the virtual machine needs to load the Guest OS.

Docker common commands

Contains basic commands, mirror commands, and container commands.

1 basic command

View some help of the command through the basic command

docker version          #View the version information of docker
docker info             #View the system information of docker, including the number of images and containers
docker command --help       #Help command (optional parameters can be viewed)
docker COMMAND --help

Help document address for the command: https://docs.docker.com/engine/reference/commandline/docker/

2 mirror command

View local images, search images, and download images from this site: https://hub.docker.com/search?q=mysql&type=image

1 docker images view all images of the local host

[root@192 ~]# docker images
hello-world   latest    bf756fb1ae65   11 months ago   13.3kB

1.REPOSITORY  Mirrored warehouse source
2.TAG  Mirrored label
3.IMAGE ID mirrored  id
4.CREATED Creation time of image
5.SIZE Mirror size

# Optional parameters
-a/--all List all mirrors
-q/--quiet Show only mirrored id

2 docker search search image

[root@192 ~]# docker search mysql
NAME                              DESCRIPTION                                     STARS     OFFICIAL   AUTOMATED
mysql                             MySQL is a widely used, open-source relation...   10308     [OK]
mariadb                           MariaDB is a community-developed fork of MyS...   3819      [OK]
mysql/mysql-server                Optimized MySQL Server Docker images. Create...   754                  [OK]
percona                           Percona Server is a fork of the MySQL relati...   517       [OK]
centos/mysql-57-centos7           MySQL 5.7 SQL database server                   86
mysql/mysql-cluster               Experimental MySQL Cluster Docker images. Cr...   79
centurylink/mysql                 Image containing mysql. Optimized to be link...   60                   [OK]

#Optional parameters
Search the Docker Hub for images
  -f, --filter filter   Filter output based on conditions provided
      --format string   Pretty-print search using a Go template
      --limit int       Max number of search results (default 25)
      --no-trunc        Don't truncate output
#Search for images with more than 3000 collections
[root@192 ~]# docker search mysql --filter=STARS=3000
NAME      DESCRIPTION                                     STARS     OFFICIAL   AUTOMATED
mysql     MySQL is a widely used, open-source relation...   10308     [OK]
mariadb   MariaDB is a community-developed fordockerk of MyS...   3819      [OK]

3 docker pull image name [: tag] Download Image

[root@192 ~]# docker pull mysql
Using default tag: latest            #If you do not write tag, the default is latest
latest: Pulling from library/mysql
6ec7b7d162b2: Pull complete          #Layered download, the core of docker image - federated file system
fedd960d3481: Pull complete
7ab947313861: Pull complete
64f92f19e638: Pull complete
3e80b17bff96: Pull complete
014e976799f9: Pull complete
59ae84fee1b3: Pull complete
ffe10de703ea: Pull complete
657af6d90c83: Pull complete
98bfb480322c: Pull complete
6aa3859c4789: Pull complete
1ed875d851ef: Pull complete
Digest: sha256:78800e6d3f1b230e35275145e657b82c3fb02a27b2d8e76aac2f5e90c1c30873 #autograph
Status: Downloaded newer image for mysql:latest
docker.io/library/mysql:latest  #The real address of the download source  #docker pull mysql is equivalent to docker pull docker io/library/mysql:latest

4 docker rmi delete image

#1. Delete the specified image id
[root@192 ~]# docker rmi -f image id
#2. Delete multiple image IDS
[root@192 ~]# docker rmi -f image id image id image id
#3. Delete all image IDS
[root@192 ~]# docker rmi -f  $(docker images -aq)

3 container command

Pull container, run container, enter container, exit container, list run containers, delete containers, start and stop containers

1. Pull the image

The premise of using the container is that the image exists, so first pull a centos container: docker pull centos

2 create, run and enter the container through image

docker run [Optional parameters] image

#Parameter description
--name="name"          Specify container name
-d                     Run in background mode
-it                    Run interactively,Enter the container to view the contents
-p                     Specify the port of the container
-p ip:Host port:Container port configuration host ports are mapped to container ports
-p Host port:Container port
-p Container port
-P                     Randomly assigned port(Capitalized P)

#Start and enter the container:
[root@192 ~]# docker run -it centos /bin/bash   
[root@192 ~]# ls      
bin  dev  etc  home  lib  lib64  lost+found  media  mnt  opt  proc  root  run  sbin  srv  sys  tmp  usr  var

If docker has no foreground application and does not provide services, it will stop automatically immediately. You can make the foreground script run by running it all the time:

#docker container runs in the background. There must be a foreground process, otherwise it will stop automatically
#Write a shell script to execute circularly to keep the centos container running
[root@192 ~]# docker run -d centos /bin/sh -c "while true;do echo hi;sleep 5;done"
[root@192 ~]# docker ps
CONTAINER ID   IMAGE     COMMAND                  CREATED          STATUS          PORTS     NAMES
c703b5b1911f   centos    "/bin/sh -c 'while t..."   13 seconds ago   Up 10 seconds             pedantic_banach
[root@192 ~]# docker logs -tf --tail 10 c703b5b1911f
2020-12-27T03:34:07.255599560Z hi
2020-12-27T03:34:12.257641517Z hi
2020-12-27T03:34:17.259706294Z hi
2020-12-27T03:34:22.261693707Z hi
2020-12-27T03:34:27.262609289Z hi
2020-12-27T03:34:32.267862677Z hi
2020-12-27T03:34:37.270382873Z hi
2020-12-27T03:34:42.272414182Z hi
2020-12-27T03:34:47.274823243Z hi
2020-12-27T03:34:52.277419274Z hi

3. Stop and exit the container

#Exit stop and exit the container (only exit if running in background mode)
#Ctrl+P+Q do not stop container exit
[root@192 ~]# exit
[root@192 ~]#

4 start and stop the container

To start and stop the container, you can use the following commands, especially when running in the background.

  container id          #Start container
docker restart container id        #Restart container
docker stop container id           #Stop the currently running container
docker kill container id           #Force stop of current container

5 list containers

#docker ps [Optional]  # Lists the currently running containers
-a           # List the operation records of all containers
-n=?         # Displays the n recently created containers
-aq          # Show all containers, only the container number

[root@192 ~]# docker ps
[root@192 ~]# docker run -it centos /bin/bash
[root@4a93ee953a85 /]# docker ps[root@192 ~]# docker ps
CONTAINER ID   IMAGE     COMMAND       CREATED              STATUS              PORTS     NAMES
4a93ee953a85   centos    "/bin/bash"   About a minute ago   Up About a minute             nervous_kowalevski
[root@192 ~]# docker ps -a
CONTAINER ID   IMAGE          COMMAND       CREATED         STATUS                     PORTS     NAMES
bca129320bb5   centos         "/bin/bash"   4 minutes ago   Exited (0) 3 minutes ago             optimistic_shtern
bd1b8900c547   centos         "/bin/bash"   6 minutes ago   Exited (0) 5 minutes ago             cool_tesla
cf6adbf1b506   bf756fb1ae65   "/hello"      5 hours ago     Exited (0) 5 hours ago               optimistic_darwin

6 delete container

docker rm container id                 #Delete the specified container. You cannot delete the running container. Force the deletion to use rm -f
docker rm -f $(docker ps -aq)    #Force the deletion of all containers, including those in operation
docker ps -a -q|xargs docker rm  #Delete all containers

4 other common commands

It includes viewing the running log, viewing the process information in the container, viewing the metadata of the container, and entering the currently running container

1 view the operation log

[root@192 ~]# docker logs --help

Usage:  docker logs [OPTIONS] CONTAINER

Fetch the logs of a container

      --details        Show extra details provided to logs
  -f, --follow         Follow log output
      --since string   Show logs since timestamp (e.g. 2013-01-02T13:23:37Z) or relative (e.g. 42m for 42 minutes)
  -n, --tail string    Number of lines to show from the end of the logs (default "all")
  -t, --timestamps     Show timestamps
      --until string   Show logs before a timestamp (e.g. 2013-01-02T13:23:37Z) or relative (e.g. 42m for 42 minutes)

Common commands are as follows:

docker logs -tf container id
docker logs --tail number container id #num is the number of log entries to display

Try it out:

#docker container runs in the background. There must be a foreground process, otherwise it will stop automatically
#Write a shell script to execute circularly to keep the centos container running
[root@192 ~]# docker run -d centos /bin/sh -c "while true;do echo tml;sleep 5;done"
[root@192 ~]# docker ps
CONTAINER ID   IMAGE     COMMAND                  CREATED          STATUS          PORTS     NAMES
c2a9905be58b   centos    "/bin/sh -c 'while t..."   7 seconds ago    Up 6 seconds              zealous_shockley
1a89c6b0a6cf   centos    "/bin/sh -c 'while t..."   2 minutes ago    Up 2 minutes              wizardly_hofstadter
3b71711140a1   centos    "/bin/bash"              18 minutes ago   Up 17 minutes             ecstatic_brattain
[root@192 ~]# docker logs -tf --tail 10 c703b5b1911f c2a9905be58b 
"docker logs" requires exactly 1 argument.
See 'docker logs --help'.

Usage:  docker logs [OPTIONS] CONTAINER

Fetch the logs of a container
[root@192 ~]# docker logs -tf --tail 10 c2a9905be58b 
2022-02-03T11:09:37.007194732Z tml
2022-02-03T11:09:42.010548527Z tml
2022-02-03T11:09:47.016344088Z tml
2022-02-03T11:09:52.019194397Z tml
2022-02-03T11:09:57.022509980Z tml
2022-02-03T11:10:02.028690964Z tml
2022-02-03T11:10:07.031701028Z tml
2022-02-03T11:10:12.035592381Z tml
2022-02-03T11:10:17.042442369Z tml
2022-02-03T11:10:22.044663053Z tml
2022-02-03T11:10:27.047141833Z tml
2022-02-03T11:10:32.051435050Z tml

2. View the process information in the container

Use the: docker top container ID command to kill the process

[root@192 ~]# docker top c2a9905be58b
UID                 PID                 PPID                C                   STIME               TTY                 TIME                CMD
root                10119               10099               0                   19:09               ?                   00:00:00            /bin/sh -c while true;do echo tml;sleep 5;done
root                10274               10119               0                   19:12               ?                   00:00:00            /usr/bin/coreutils --coreutils-prog-shebang=sleep /usr/bin/sleep 5
[root@192 ~]# 

3. View metadata of container

Thoroughly understand the metadata in the container image: docker inspect container ID

4 enter the currently running container

Generally, our container runs in the background mode. Sometimes we need to enter the container to modify the configuration. At this time, there are two ways:

  • After entering the container, open a new terminal, which can be operated inside
[root@192 ~]# docker exec -it c703b5b1911f /bin/bash
[root@192 ~]# ls
bin  dev  etc  home  lib  lib64  lost+found  media  mnt  opt  proc  root  run  sbin  srv  sys  tmp  usr  var
[root@192 ~]# ps -ef      
root         1     0  0 03:31 ?        00:00:00 /bin/sh -c while true;do echo hi;sleep 5;done
root       279     0  0 03:54 pts/0    00:00:00 /bin/bash
root       315     1  0 03:56 ?        00:00:00 /usr/bin/coreutils --coreutils-prog-shebang=sleep /usr/bin/sleep 5
root       316   279  0 03:56 pts/0    00:00:00 ps -ef

  • Entering the terminal where the container is executing will not start a new process
[root@192 ~]# docker attach c703b5b1911f

5 container host copy command

#Copy container files to host
docker cp container id:In container path destination host path

#Copy the files of the host to the container
docker cp Destination host path container id:Path in container

Execute the following command to copy the container file to the host

[root@192 ~]# docker exec -it c2a9905be58b /bin/bash
[root@192 ~]# cd home
[root@192 ~]# ls
#touch new file
[root@192 ~]# touch test.java
[root@192 ~]# ls
[root@192 ~]# exit
[root@192 ~]# docker ps
CONTAINER ID   IMAGE     COMMAND                  CREATED          STATUS          PORTS     NAMES
c2a9905be58b   centos    "/bin/sh -c 'while t..."   35 minutes ago   Up 35 minutes             pedantic_banach
[root@192 ~]# docker cp c2a9905be58b:/home/test.java /home
[root@192 ~]# ls /home
test.java  tml-1

To sum up

The concept of Docker warehouse is a bit like Maven [Jar package hosting warehouse] and GitHub [code hosting warehouse], which is a mirror hosting warehouse. This Blog introduces in detail how to download and install Docker and how to speed up the image, understands the basic operation process of Docker, and actually runs through the use process of Docker through common Docker commands such as basic commands, image commands, container commands and log commands. Next, we will further deepen our understanding of Docker through the study of principles!

Keywords: Operation & Maintenance CentOS Docker

Added by randomfool on Thu, 03 Feb 2022 17:12:49 +0200