What is docker!
Docker's idea comes from the container. What problem does the container solve? In a large ship, the goods can be placed neatly. And all kinds of goods are standardized by containers, and containers will not affect each other. Then I don't need a ship for fruit and a ship for chemicals. As long as the goods are well sealed in containers, I can take them all away in a big ship
OCI!!
- Led by the Linux foundation, it was founded in June 2015
- It aims to develop an open industrial standard around container format and runtime
- Contains two specifications
- Runtime spec
- Image spec
OCF!!
runC is a CLI tool for generating and running containers according to the OCI specification
- The container is started as a child process of runC, and can be embedded in various other systems without running a daemon
- runC is built on libcontainer. The same container technology supports the installation of numerous docker engines. Docker provides a site dedicated to container images: https://hub.docker.com
docker architecture!!
- Generally, the client and server are on the same host
- The client side uses various docker commands to manage containers
- There can be multiple containers, images and local storage on the server side
- The registry can provide images of different system types
Workflow
First, the client uses the docker command
- After the server detects the command, first check whether there is an image in the local area
-If there is no mirror to operate on, you can start from hub Pull image from docker to local - At this time, if the local image already has the image to be operated, the operation can be performed directly
How docker works
-
Docker is a C/S architecture, which is used to manage containers. The daemon of docker runs on the host and communicates through socket.
-
The server receives the instruction from the client through the socket, and will execute the command after receiving the instruction. docker establishes the boundary of the container by modifying the system call parameters of namespaces.
-
docker uses CGroups (control groups) to manage (restrict) the resource occupation of a container to avoid resource preemption between containers.
docker image and image warehouse
- tag is the version number of the application
- Latest is the latest version
- Stable is a stable version
- The image is static, while the container is dynamic. The container has its life cycle. The relationship between the image and the container is similar to that between the program and the process. The image is similar to the program file in the file system, while the container is similar to the state in which a program runs, that is, the process. Therefore, containers can be deleted. After a container is deleted, its image will not be deleted.
docker object
When you use docker, you can create, use, and manage images, containers, networks, storage volumes, plug-ins, and other objects.
-
image
- A mirror is a read-only template used to create containers - Usually, the creation of one image is based on another system image, and some customized operations are carried out, such as installing and starting a service - You can create your own image or use the image created by others to pull it locally (it is recommended to use the official image)
-
container
- A container is a running image - Can be in API Interface or on the command line to create, run, stop, move, and delete your container - You can connect containers to one or more networks, attach storage volumes to them, and even create a new mirror based on the current state
docker installation
[root@master ~]# cd /etc/yum.repos.d/ [root@master yum.repos.d]# vim docker-ce.repo [root@master yum.repos.d]# cat docker-ce.repo [docker-ce] name=docker-ce baseurl=https://mirrors.aliyun.com/docker-ce/linux/centos/8/x86_64/stable/ gpgcheck=1 gpgkey=https://mirrors.aliyun.com/docker-ce/linux/centos/gpg enabled=1 [root@master yum.repos.d]# dnf clean all 26 File deleted [root@master yum.repos.d]# dnf -y install docker-ce CentOS Stream 8 - AppStream 112 kB/s | 12 MB 01:48 CentOS Stream 8 - BaseOS 99 kB/s | 7.7 MB 01:19 CentOS Stream 8 - Extras 1.3 kB/s | 14 kB 00:10 docker-ce 2.1 kB/s | 14 kB 00:06 Salt repo for RHEL/CentOS 8 PY3 12 kB/s | 242 kB 00:20
docker acceleration
The configuration file of docker CE is / etc/docker / daemon JSON, this file does not exist by default. We need to create and configure it manually. The / etc/docker directory is generated after docker is started, and the acceleration of docker is realized by configuring this file.
docker can be accelerated in many ways:
- docker cn
- Accelerator of China University of science and technology
- Alicloud accelerator (you need to register an account through alicloud Developer Platform and use your own accelerator for free)
[root@master ~]# cd /etc/docker/
[root@master docker]# ls
key.json
[root@master docker]# vim deamon.json
[root@master docker]# cat deamon.json
{
"registry-mirrors": ["https://5ryw5lau.mirror.aliyuncs.com"]
}
[root@master docker]# systemctl daemon-reload
[root@master docker]# systemctl restart docker
docker common operations
| command | function |
|---|---|
| docker search | Used to find images on docker hub |
| docker pull | Used to pull the specified image on the docker |
| docker images | Used to view the current system image information |
| docker create | Used to create containers |
| docker start | Used to start one or more containers |
| docker run | When there is no local image, automatically pull the image and create and start the container |
| docker attach | Used to enter a specified container |
| docker ps | Used to view information about containers in the system |
| docker logs | Used to view the logs of containers in the system |
| docker restart | Used to restart the specified container |
| docker stop | Used to stop the specified container |
| docker kill | The process used to kill the specified container |
| docker rm | Used to delete containers |
| docker exec | Used to enter a specified container and execute commands |
| docker info | Used to view the details of the docker tool |
| docker inspect | Used to view the details of a specified object |
docker search
[root@master docker]# docker search httpd NAME DESCRIPTION STARS OFFICIAL AUTOMATED httpd The Apache HTTP Server Project 3598 [OK] centos/httpd-24-centos7 Platform for running Apache httpd 2.4 or bui... 40 centos/httpd 34 [OK] arm64v8/httpd The Apache HTTP Server Project 7 polinux/httpd-php Apache with PHP in Docker (Supervisor, CentO... 5 [OK] solsson/httpd-openidc mod_auth_openidc on official httpd image, ve... 2 [OK] hypoport/httpd-cgi httpd-cgi 2 [OK] centos/httpd-24-centos8 1 clearlinux/httpd httpd HyperText Transfer Protocol (HTTP) ser... 1 inanimate/httpd-ssl A play container with httpd, ssl enabled, an... 1 [OK] dockerpinata/httpd 1 dariko/httpd-rproxy-ldap Apache httpd reverse proxy with LDAP authent... 1 [OK] manageiq/httpd Container with httpd, built on CentOS for Ma... 1 [OK] jonathanheilmann/httpd-alpine-rewrite httpd:alpine with enabled mod_rewrite 1 [OK] publici/httpd httpd:latest 1 [OK] lead4good/httpd-fpm httpd server which connects via fcgi proxy h... 1 [OK] interlutions/httpd httpd docker image with debian-based config ... 0 [OK] appertly/httpd Customized Apache HTTPD that uses a PHP-FPM ... 0 [OK] amd64/httpd The Apache HTTP Server Project 0 manasip/httpd 0 manageiq/httpd_configmap_generator Httpd Configmap Generator 0 [OK] trollin/httpd 0 itsziget/httpd24 Extended HTTPD Docker image based on the off... 0 [OK] ysli/httpd Httpd for DeepWeb 0 [OK] e2eteam/httpd 0
docker pull
[root@master docker]# docker pull httpd Using default tag: latest latest: Pulling from library/httpd 33847f680f63: Pull complete d74938eee980: Pull complete 963cfdce5a0c: Pull complete 8d5a3cca778c: Pull complete e06a573b193b: Pull complete Digest: sha256:61e49dd08a51d6fc421ed257bd8eb461cf2d48269d9ab2b4ff5d4c69826c3c9c Status: Downloaded newer image for httpd:latest docker.io/library/httpd:latest
docker images
[root@master docker]# docker images REPOSITORY TAG IMAGE ID CREATED SIZE httpd latest 73b8cfec1155 5 days ago 138MB
docker create
[root@master docker]# docker create httpd 9e84110fa7fdf26df44d3655469115b5cbf8b77f7247413a83472ede7f44be75
docker ps
[root@master docker]# docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES [root@master docker]# docker ps -a CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 9e84110fa7fd httpd "httpd-foreground" 51 seconds ago Created gallant_swartz
docker start
[root@master docker]# docker start 9e84110fa7fd 9e84110fa7fd [root@master docker]# docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 9e84110fa7fd httpd "httpd-foreground" About a minute ago Up 16 seconds 80/tcp gallant_swartz
docker run
[root@master docker]# docker run httpd AH00558: httpd: Could not reliably determine the server's fully qualified domain name, using 172.17.0.3. Set the 'ServerName' directive globally to suppress this message AH00558: httpd: Could not reliably determine the server's fully qualified domain name, using 172.17.0.3. Set the 'ServerName' directive globally to suppress this message [Wed Jul 28 04:06:47.644621 2021] [mpm_event:notice] [pid 1:tid 140665671206016] AH00489: Apache/2.4.48 (Unix) configured -- resuming normal operations [Wed Jul 28 04:06:47.644815 2021] [core:notice] [pid 1:tid 140665671206016] AH00094: Command line: 'httpd -D FOREGROUND' [root@master ~]# docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 85e481d357ba httpd "httpd-foreground" 26 seconds ago Up 25 seconds 80/tcp sad_jemison 9e84110fa7fd httpd "httpd-foreground" 3 minutes ago Up About a minute 80/tcp gallant_swartz # When ctrl+c terminates, the container will also stop [root@master ~]# docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 9e84110fa7fd httpd "httpd-foreground" 3 minutes ago Up About a minute 80/tcp gallant_swartz
docker attach
[root@master ~]# docker attach 9e84110fa7fd ^C[Wed Jul 28 04:08:46.947770 2021] [mpm_event:notice] [pid 1:tid 140190087959680] AH00491: caught SIGTERM, shutting down [root@master ~]# docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
docker logs
[root@master docker]# docker start 9e84110fa7fd 9e84110fa7fd [root@master docker]# docker logs 9e84110fa7fd AH00558: httpd: Could not reliably determine the server's fully qualified domain name, using 172.17.0.2. Set the 'ServerName' directive globally to suppress this message AH00558: httpd: Could not reliably determine the server's fully qualified domain name, using 172.17.0.2. Set the 'ServerName' directive globally to suppress this message [Wed Jul 28 04:05:45.499920 2021] [mpm_event:notice] [pid 1:tid 140190087959680] AH00489: Apache/2.4.48 (Unix) configured -- resuming normal operations [Wed Jul 28 04:05:45.500715 2021] [core:notice] [pid 1:tid 140190087959680] AH00094: Command line: 'httpd -D FOREGROUND' [Wed Jul 28 04:08:46.947770 2021] [mpm_event:notice] [pid 1:tid 140190087959680] AH00491: caught SIGTERM, shutting down AH00558: httpd: Could not reliably determine the server's fully qualified domain name, using 172.17.0.2. Set the 'ServerName' directive globally to suppress this message AH00558: httpd: Could not reliably determine the server's fully qualified domain name, using 172.17.0.2. Set the 'ServerName' directive globally to suppress this message [Wed Jul 28 04:10:02.414826 2021] [mpm_event:notice] [pid 1:tid 140048856097920] AH00489: Apache/2.4.48 (Unix) configured -- resuming normal operations [Wed Jul 28 04:10:02.415084 2021] [core:notice] [pid 1:tid 140048856097920] AH00094: Command line: 'httpd -D FOREGROUND'
docker stop
[root@master docker]# docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 9e84110fa7fd httpd "httpd-foreground" 6 minutes ago Up About a minute 80/tcp gallant_swartz [root@master docker]# docker stop 9e84110fa7fd 9e84110fa7fd [root@master docker]# docker ps CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
docker rm
[root@master ~]# docker rm 9e84110fa7fd 9e84110fa7fd [root@master ~]# docker ps -a CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 85e481d357ba httpd "httpd-foreground" 8 minutes ago Exited (0) 7 minutes ago sad_jemison
docker event state
