Virtualization is a resource management technology, which is abstracted from computer hardware resources, breaking the indivisible barrier of hardware entities, and users can configure these hardware resources according to their needs. The new virtual part of these resources is not restricted by the way existing resources are erected, geographical or physical configuration. Generally referred to as virtualized resources include computing power and data storage.
Application: such as cloud server, virtual machine, etc.
Docker is an open source application container engine, based on the Go language and open source in compliance with the Apache2.0 protocol.
Docker allows developers to package their applications and dependent packages into a lightweight, portable container, and then publish to any popular Linux machine, it can also be virtualized.
Containers use the sandbox mechanism completely, and there will be no interfaces between each other (apps similar to iPhone), and more importantly, the container performance overhead is extremely low.
The 17 in docker's 17.0x refers to 2017. Looking at it now, the beginning of 17 is the old version, and the newer version is 19.xx
We need to install the operating system in the virtual machine, and then install the software we need on the operating system.
Install docker on host os, and then we can go to the docker warehouse to pull the software we need. These software is equivalent to the Linux operating system, but it is much smaller than the directly installed Linux operating system. Containers are isolated from each other. A docker engine can start multiple containers at the same time. These containers do not interfere with each other. We can also start the operating system on docker.
Docker can quickly deliver and deploy projects, more efficient virtualization, easier red migration and expansion, and simpler management.
The docker engine is an application of c/s structure, and the main components are shown in the following figure:
note:
Docker containers are created through Docker images.
The relationship between containers and mirrors is similar to objects and classes in object-oriented programming.
Docker ------> object-oriented
Container------> Object
Mirror------> Class
Docker uses the C/S architecture, and the Client communicates with the Server process through the interface to implement the construction, operation and release of the container. The client and server can run on the same cluster, or they can communicate remotely through cross-hosts.
client: client
docker_host: host host
registry: Warehouse: private server and central warehouse (Docker Hub)
The ocker image is a template for creating Docker containers
A container is an application or a group of applications that run independently
The Docker client uses the Docker API ( https://docs.docker.com/reference/api/docker_remote_api ) to communicate with the Docker daemon through the command line or other tools .
A physical or virtual machine is used to execute the Docker daemon and container.
The Docker warehouse is used to store images, which can be understood as a code warehouse in code control.
Docker Hub ( https://hub.docker.com ) provides a huge collection of images for use.
Docker supports windows, Linux, and macOS operating systems. The official recommendation is to use the Linux Ubuntu operating system, because Docker is based on Ubuntu, and Ubuntu is the first to be updated or patched when it comes to problems with Docker.
Because of the centos I use, I will only introduce the installation of docker on centos for the time being. It is recommended to install the version above CentOS7.x. In the version of CentOS6.x, many other environments need to be installed before installation, and many patches of docker are not Support updates.
sudo yum update
yum-util provides the yum-config-manager function, the other two are dependent on the devicemapper driver
sudo yum install -y yum-utils device-mapper-persistent-data lvm2
sudo yum-config-manager --add-repo http://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo
sudo yum install docker-ce
docker -v
Ustc is an old linux mirroring service provider, and it was still in use in the distant ubuntu 5.04 version. ustc's docker image accelerator is very fast. One of the advantages of ustc docker mirror is that it does not require registration and is a true public service.
https://lug.ustc.edu.cn/wiki/mirrors/help/docker
Edit the file:
vi/etc/docker/daemon.json
Enter the following in the file:
{
"registry-mirrors": ["https://o9q9m998.mirror.aliyuncs.com"]
}
#Configure the source (if you can't start it, you don't strictly follow the josn format, just check it)It is best to set the mirror source of ustc to be a domestic source, otherwise the speed of pulling mirrors from the warehouse will be very slow. I personally think that the domestic Qiniu Cloud https://reg-mirror.qiniu.com and Alibaba Cloud mirror sources will be faster. Alibaba source needs to log in to Alibaba Cloud https://cr.console.aliyun.com/cn-hangzhou/instances/repositories to apply, and Alibaba will open a source separately for you, and the above is the application.
The configuration needs to restart the docker service
systemctl restart docker
The systemctl command is a system service manager command
Start docker:
systemctl start docker
Stop docker:
systemctl stop docker
Restart docker:
systemctl restart docker
View docker status:
systemctl status docker
boot:
systemctl enable docker
View docker summary information
docker info
View the docker help documentation
docker --help
docker images
REPOSITORY: mirror name
TAG: Mirror tag
IMAGE ID: Image ID
CREATED: The creation date of the image (not the date when the image was obtained)
SIZE: image size
These images are stored in the/var/lib/docker directory of the Docker host
docker images -q
View the IMAGE ID of all mirrors
If you need to find the required mirror from the network, you can search through the following command
docker search image name
NAME: Warehouse name
DESCRIPTION: mirror description
STARS: User reviews, reflecting the popularity of a mirror
OFFICIAL: Is it official
AUTOMATED: Automatically build, indicating that the image was created by the Docker Hub automatic build process
To pull a mirror is to download the mirror from the central warehouse to the local
docker pull image name
For example, I want to download the centos7 mirror
docker pull centos:7
Delete mirror by mirror ID
docker rmi image ID
Delete all mirrors (use with caution)
docker rmi `docker images -q`
View running containers
docker ps
View all containers
docker ps –a
View the last run container
docker ps –l
View stopped containers
docker ps -f status=exited
Description of commonly used parameters for container creation:
Create container command: docker run
-i: means running the container
-t: indicates that the container will enter its command line after it is started. After adding these two parameters, the container creation can log in. That is, a pseudo terminal is allocated.
--name: Name the created container.
-v: Represents the directory mapping relationship (the former is the host directory, the latter is the directory mapped to the host), you can use multiple -v to do multiple directory or file mapping. Note: It is best to do directory mapping, make changes on the host, and then share to the container.
-d: Add the -d parameter after run, it will create a guardian container to run in the background (so that the container will not be automatically logged in after the container is created, if only the -i -t two parameters are added, it will automatically enter after creation container).
-p: Represents port mapping, the former is the host port, and the latter is the mapping port in the container. You can use multiple -p to do multiple port mapping
(1) Create a container interactively
docker run -it --name=container name image name: label/bin/bash docker run -di --name=mycentos2 centos:7 # docker run -d -i --name=mycentos2 centos:7 # Each container has its own id number: b1eeace155b54e467dfcbc42bb2fa5b580db5463f230a3eae1b27b74de4c597 docker run -d -i --name=mycentos3 centos:6.5 # If the latest centos image is not available locally, pull it first, then create and allow it # Start a redis container docker run -di --name=myredis -p 6379:6379 redis # Stop the reids of this machine # Port mapping, 6378 6379 # Use docker to allow a service (install a software), it becomes very simple -Linux installation redis (source download, decompression, make & make insall)
At this time, we use the ps command to view and find that we can see the started container, and the status is started.
Exit the current container
exit
(2) Create a container in a guardian way:
docker run -di --name=container name image name: label
Log in to the guardian container:
docker exec -it container name (or container ID)/bin/bash
Stop the container:
docker stop container name (or container ID)
Start the container:
docker start container name (or container ID)
If we need to copy files to the container, we can use the cp command
docker cp file or directory to be copied Container name: container directory
You can also copy files from the container
docker cp container name: the file or directory that needs to be copied in the container directory
When creating the container, we can map the directory of the host machine to the directory in the container, so that we can modify the file in a certain directory of the host machine to affect the container. Create a container and add the -v parameter to the host directory: container directory, for example:
docker run -di -v/usr/local/myhtml:/usr/local/myhtml --name=mycentos3 centos:7
If you are sharing a multi-level directory, you may be prompted with insufficient permissions.
This is because the security module selinux in CentOS7 has disabled the permissions, we need to add the parameter --privileged=true to solve the problem that the mounted directory does not have permissions
We can view various data of the container running through the following commands
docker inspect container name (container ID)
You can also directly execute the following command to directly output the IP address
docker inspect --format='{{.NetworkSettings.IPAddress}}' container name (container ID)Delete the specified container:
docker rm container name (container ID)