Detailed explanation of common operations of Docker images and containers

Image Accelerator

Sometimes it is difficult to pull images from Docker Hub in China. In this case, you can configure an image accelerator. Many domestic cloud service providers provide domestic accelerator services, such as:

NetEase Cloud Accelerator https://hub-mirror.c.163.com
Alibaba Cloud Accelerator (need to log in to obtain): https://cr.console.aliyun.com/cn-hangzhou/mirrors

All major domestic cloud service providers provide Docker image acceleration services. It is recommended to select the corresponding image acceleration service according to the cloud platform running Docker. For details, please refer to the official documentation.

In CentOS7 system, please write the following content in /etc/docker/daemon.json (if the file does not exist, please create a new file)

[root@docker01 ~]# vim /etc/docker/daemon.json
{
 "registry-mirrors": [
  "https://hub-mirror.c.163.com"
 ]
}

Note that you must ensure that the file complies with the json specification, otherwise Docker will not be able to start.

Restart the service afterwards.

systemctl daemon-reload
systemctl restart docker

Check whether the accelerator is effective

Execute the following command. If you see the following content in the result, it means the configuration is successful.

[root@docker01 ~]# docker info # Display information of the entire system………………
Registry Mirrors:
 https://hub-mirror.c.163.com/
Live Restore Enabled: false

WARNING: bridge-nf-call-iptables is disabled
WARNING: bridge-nf-call-ip6tables is disabled

Docker mirror operation

Note: Before Docker runs a container, the corresponding image must exist locally. If the image does not exist locally, Docker will download the image from the image repository.

searchSearch mirror

[root@docker01 ~]# docker search centos
NAME DESCRIPTION STARS OFFICIAL AUTOMATED
centos The official build of CentOS. 5934 [OK]    
ansible/centos7-ansible Ansible on Centos7 128 [OK]
jdeathe/centos-ssh OpenSSH / Supervisor / EPEL/IUS/SCL Repos - … 114 [OK]
consol/centos-xfce-vnc Centos container with "headless" VNC session… 114 [OK]
centos/mysql-57-centos7 MySQL 5.7 SQL database server 74        
…………

Pull Download the image from the mirror center

# Format: docker pull <image_name>:<tag>, if there is no tag, the default is latest
[root@docker01 ~]# docker pull centos:latest
latest: Pulling from library/centos
8a29a15cefae: Pull complete 
Digest: sha256:fe8d824220415eed5477b63addf40fb06c3b049404242b31982106ac204f6700
Status: Downloaded newer image for centos:latest

push Push the image to the image center

Format: docker push <image_name>:<tag>
[root@docker01 ~]# docker push registry.cn-beijing.aliyuncs.com/google_registry/centos:latest

Note: If you have any questions, you can ignore them for now. The article on building a private warehouse will explain it again later.

images List images

[root@docker01 ~]# docker images # or docker image ls
REPOSITORY TAG IMAGE ID CREATED SIZE
centos latest 470671670cac 2 months ago 237MB

Save the image to local

# Format: docker save -o <saved file name> <image_name:tag>|<image_id>
[root@docker01 docker_test]# docker save -o centos_docker_20200413.tar centos:latest 
[root@docker01 docker_test]# ll -h
total 234M
-rw------ 1 root root 234M Apr 13 16:21 centos_docker_20200413.tar

rmi delete image

# Format: docker rmi <image_name:tag>|<image_id>
[root@docker01 docker_test]# docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
centos latest 470671670cac 2 months ago 237MB
[root@docker01 docker_test]# docker rmi 470671670cac # Delete the image [root@docker01 docker_test]# docker images
REPOSITORY TAG IMAGE ID CREATED SIZE

loadImport image

# Format: docker load -i <image_file>
[root@docker01 docker_test]# docker load -i centos_docker_20200413.tar
[root@docker01 docker_test]# docker images 
REPOSITORY TAG IMAGE ID CREATED SIZE
centos latest 470671670cac 2 months ago 237MB

tag

# Format: docker tag SOURCE_IMAGE[:TAG] TARGET_IMAGE[:TAG]
[root@docker01 docker_test]# docker images 
REPOSITORY TAG IMAGE ID CREATED SIZE
centos latest 470671670cac 2 months ago 237MB 
[root@docker01 docker_test]# docker tag centos:latest centos:20200413
[root@docker01 docker_test]# docker images 
REPOSITORY TAG IMAGE ID CREATED SIZE
centos 20200413 470671670cac 2 months ago 237MB
centos latest 470671670cac 2 months ago 237MB

Usage: Give the docker image a new tag as needed.

info displays information about the entire system

[root@docker01 ~]# docker info 
Containers: 0
 Running: 0
 Paused: 0
 Stopped: 0
Images: 1
Server Version: 18.06.3-ce
Storage Driver: overlay2
 Backing Filesystem: xfs
 Supports d_type: true
 Native Overlay Diff: true
Logging Driver: json-file
Cgroup Driver: cgroupfs
Plugins:
 Volume: local
 Network: bridge host macvlan null overlay
 Log: awslogs fluentd gcplogs gelf journald json-file logentries splunk syslog
Swarm: inactive
Runtimes: runc
Default Runtime: runc
Init Binary: docker-init
containerd version: 468a545b9edcd5932818eb9de8e72413e616e86e
runc version: a592beb5bc4c4092b1b1bac971afed27687340c5
init version: fec3683
Security Options:
 seccomp
 Profile: default
Kernel Version: 3.10.0-1062.el7.x86_64
Operating System: CentOS Linux 7 (Core)
OSType: linux
Architecture: x86_64
CPUs: 2
Total Memory: 1.777 GiB
Name: docker01
ID: XIHU:XNWU:II7A:YXUH:BOZ3:JSGG:J3P2:CU2Z:5QHA:5Y64:PZ4V:62DI
Docker Root Dir: /var/lib/docker
Debug Mode (client): false
Debug Mode (server): false
Registry: https://index.docker.io/v1/
Labels:
Experimental: false
Insecure Registries:
 127.0.0.0/8
Registry Mirrors:
 https://hub-mirror.c.163.com/
Live Restore Enabled: false

WARNING: bridge-nf-call-iptables is disabled
WARNING: bridge-nf-call-ip6tables is disabled

System image volume view

Another thing to note is that the total size of the images in the docker image ls list is not the actual disk consumption of all images. Since Docker images are multi-layer storage structures that can be inherited and reused, different images may have common layers because they use the same base image. Since Docker uses Union FS, only one copy of the same layer needs to be saved, so the actual image hard disk space occupied is likely to be much smaller than the sum of the image sizes in this list.

You can use the following command to easily view the space occupied by images, containers, and data volumes.

[root@docker01 docker_test]# docker system df
TYPE TOTAL ACTIVE SIZE RECLAIMABLE
Images 2 0 440.1MB 440.1MB (100%)
Containers 0 0 0B 0B
Local Volumes 0 0 0B 0B
Build Cache 0 0 0B 0B

inspect displays details of an image or container

# Format: docker inspect <image ID>|<image name>|<container ID>|<container name>
[root@docker01 ~]# docker inspect centos:latest # Display image details [root@docker01 ~]# docker inspect 67ba647b0151 # Display container details

Docker container operation

Run to create a container

# Format: docker run [OPTIONS] IMAGE [COMMAND] [ARG...]
[root@docker01 ~]# docker run -i -t --name centos01 centos:latest /bin/bash
[root@f7c4da3cecad /]# # Now you have entered the docker container [root@f7c4da3cecad /]# exit # Exit the container, the container will stop [normal situation]
[root@docker01 ~]#

Parameter Description:

-i interactive operation
-t allocate a terminal
--name The name of the container to run The command to be executed at the end of /bin/bash

ps view container

[root@docker01 ~]# docker ps # View the running container CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
[root@docker01 ~]# 
[root@docker01 ~]# docker ps -a # View all containers, including running and stopped CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
f7c4da3cecad centos:latest "/bin/bash" 4 minutes ago Exited (0) 36 seconds ago centos01

startStart the container

# Format: docker start <container name>|<container ID>
[root@docker01 ~]# docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
f7c4da3cecad centos:latest "/bin/bash" 10 minutes ago Exited (0) 3 seconds ago centos01
[root@docker01 ~]# docker start f7c4da3cecad # Start container f7c4da3cecad
[root@docker01 ~]# docker ps 
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
f7c4da3cecad centos:latest "/bin/bash" 10 minutes ago Up 3 seconds centos01

restart restarts the container

# Format: docker restart <container name>|<container ID>
[root@docker01 ~]# docker ps 
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
f7c4da3cecad centos:latest "/bin/bash" 15 minutes ago Up 4 minutes centos01
[root@docker01 ~]# docker restart f7c4da3cecad # Restart container f7c4da3cecad
[root@docker01 ~]# docker ps 
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
f7c4da3cecad centos:latest "/bin/bash" 15 minutes ago Up 1 second centos01

stopStop the container

# Format: docker stop <container name>|<container ID>
[root@docker01 ~]# docker ps 
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
f7c4da3cecad centos:latest "/bin/bash" 3 hours ago Up 4 minutes centos01
[root@docker01 ~]# docker stop f7c4da3cecad # Stop container f7c4da3cecad
[root@docker01 ~]# docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
f7c4da3cecad centos:latest "/bin/bash" 3 hours ago Exited (0) 10 seconds ago centos01

rm removes the container

# Format: docker rm <container name>|<container ID>
[root@docker01 ~]# docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
f7c4da3cecad centos:latest "/bin/bash" 3 hours ago Exited (0) 10 seconds ago centos01
[root@docker01 ~]# docker rm f7c4da3cecad # Delete the stopped container f7c4da3cecad

Note: If you want to forcibly delete a running container, use docker rm -f <container ID>. However, it is not recommended to force delete containers in production environments to prevent accidental deletion.

rename container rename

# Format: docker rename CONTAINER NEW_NAME
[root@docker01 ~]# docker ps 
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
67ba647b0151 centos:latest "/bin/bash" About a minute ago Up About a minute centos01
[root@docker01 ~]# docker rename 67ba647b0151 centos001 # container rename [root@docker01 ~]# docker ps 
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
67ba647b0151 centos:latest "/bin/bash" 2 minutes ago Up About a minute centos001

exec into a container or execute a command in a running container

Entering the container

[root@docker01 ~]# docker exec -it f7c4da3cecad bash
[root@f7c4da3cecad /]#

Note: It is not recommended to enter the container through docker attach.

Let the specified container execute commands outside the container

# Don't have the -t option, because there is no need to allocate a tty terminal [root@docker01 ~]# docker exec -i f7c4da3cecad bash -c "ps -ef"
UID PID PPID C STIME TTY TIME CMD
root 1 0 0 10:12 pts/0 00:00:00 /bin/bash
root 78 0 0 10:19 ? 00:00:00 ps -ef

cp copies files or directories

Copy the host file or directory to the Docker container

[root@docker01 ~]# docker exec -i 67ba647b0151 bash -c "ls -l /root"
total 12
-rw------ 1 root root 2366 Jan 13 21:49 anaconda-ks.cfg
-rw-r--r-- 1 root root 435 Jan 13 21:49 anaconda-post.log
-rw------ 1 root root 2026 Jan 13 21:49 original-ks.cfg
[root@docker01 ~]# 
[root@docker01 ~]# docker cp /usr/bin/telnet 67ba647b0151:/root/ # Copy file[root@docker01 ~]# docker cp /root/basedOptimi 67ba647b0151:/root/ # Copy directory[root@docker01 ~]# docker exec -i 67ba647b0151 bash -c "ls -l /root"
total 112
-rw------ 1 root root 2366 Jan 13 21:49 anaconda-ks.cfg
-rw-r--r-- 1 root root 435 Jan 13 21:49 anaconda-post.log
drwxr-xr-x 2 root root 30 Mar 8 19:59 basedOptimi
-rw------ 1 root root 2026 Jan 13 21:49 original-ks.cfg
-rwxr-xr-x 1 root root 101776 Aug 3 2017 telnet

Copy files or directories in the Docker container to the host machine

[root@docker01 ~]# docker cp 67ba647b0151:/root/original-ks.cfg /root/ # Copy file [root@docker01 ~]# docker cp 67ba647b0151:/etc /root/ # Copy directory

logsView container logs

[root@docker01 ~]# docker ps 
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
f7c4da3cecad centos:latest "/bin/bash" 3 hours ago Up 1 second centos01
# Get container logs [root@docker01 ~]# docker logs -f --tail 500 f7c4da3cecad
…………

Parameter Description:

-f print output continuously
--tail 500 print the last 500 lines of the log

stats container resource usage statistics

Can be used for monitoring

[root@docker01 ~]# docker stats <container ID>|<container name> # Continuous monitoring [root@docker01 ~]# docker stats --no-stream <container ID>|<container name> # Not continuous monitoring, only the first returned result is displayed

Processes running in top container

[root@docker01 ~]# docker ps 
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
67ba647b0151 centos:latest "/bin/bash" 2 hours ago Up 2 hours centos001 
# View the process information running in the container [root@docker01 ~]# docker top 67ba647b0151
UID PID PPID C STIME TTY TIME CMD
root 3302 3285 0 21:13 pts/0 00:00:00 /bin/bash

The port container maps a specific port

The container mapping ports are: random port mapping, specify a single port mapping, specify multiple port mappings

Get the image

[root@docker01 ~]# docker pull registry.cn-beijing.aliyuncs.com/google_registry/nginx:1.17
[root@docker01 ~]# docker tag ed21b7a8aee9 nginx:1.17
[root@docker01 ~]# docker images | grep 'nginx'
nginx 1.17 ed21b7a8aee9 2 weeks ago 127MB
registry.cn-beijing.aliyuncs.com/google_registry/nginx 1.17 ed21b7a8aee9 2 weeks ago 127MB

Mapping random ports

[root@docker01 ~]# docker run -d -P --name nginx01 nginx:1.17
e90c9faaf8e3387920dd9763bf5c7df9dd17856673868bb512cec78741ff71dc
[root@docker01 ~]# docker ps 
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
e90c9faaf8e3 nginx:1.17 "nginx -g 'daemon of..." 3 seconds ago Up 2 seconds 0.0.0.0:1025->80/tcp nginx01

illustrate:

0.0.0.0:1025->80/tcp The first part is the host port, and the second part is the container port

Container logs:

[root@docker01 ~]# docker logs -f --tail 500 nginx01

Browser access:

Map a single specified port

[root@docker01 ~]# docker run -d -p 81:80 --name nginx02 nginx:1.17
04478222f0dc981883f25504164be3af7da49248886cee7386ccc89b80cc57a1
[root@docker01 ~]# docker ps | grep 'nginx02'
04478222f0dc nginx:1.17 "nginx -g 'daemon of..." 29 seconds ago Up 28 seconds 0.0.0.0:81->80/tcp nginx02

Browser access:

Map multiple specified ports

[root@docker01 ~]# docker run -d -p 85:80 -p 445:443 --name nginx03 nginx:1.17
5886e52ff8e934bc827c8d7753a532b9062bd045799d0658a008e371e6ecd09c
[root@docker01 ~]# docker ps | grep 'nginx03'
5886e52ff8e9 nginx:1.17 "nginx -g 'daemon of..." 12 seconds ago Up 11 seconds 0.0.0.0:85->80/tcp, 0.0.0.0:445->443/tcp nginx03

Recommended Reading
1. Docker Introduction and Installation

This is the end of this article about common operations of Docker images and containers. For more relevant Docker images and container operations, please search for previous articles on 123WORDPRESS.COM or continue to browse the following related articles. I hope everyone will support 123WORDPRESS.COM in the future!

You may also be interested in:

Example of setting up a private Docker image repository on a CentOS 7.2 server
Summary of common Docker commands: installation, mirroring, and basic container operations
How to delete the container created in Docker
Docker container operation instructions summary and detailed explanation
Tutorial on importing and exporting Docker containers
How to install docker on Linux system and log in to docker container through ssh
How to mount the host directory in Docker container
Solution to exiting the Docker container
Getting Started Guide to Using IPython with Docker Containers

<<: How to implement scheduled automatic backup of MySQL under CentOS7

>>: Vue3 realizes the image magnifying glass effect