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 the container, I can take them all away in a big ship.
Some people say that docker is a container, while others say that docker is not a container. In my opinion, docker is more like a container for loading containers;, A large ship is a container, and then each container is a small container; Let's look at the docker icon;
The most important is the concept of image layering; At the bottom is the operating system. The penultimate layer is the basic image. In the middle is the service installed on the basic image, and at the top is the container layer; At first glance, it looks like containers are nested;
After introducing docker, let's see what commands docker has!
Start and stop docker
# start-up systemctl start docker # Daemon restart sudo systemctl daemon-reload # Restart docker service systemctl restart docker # Restart docker service sudo service docker restart # Close docker service docker stop # Close docker systemctl stop docker
Help command
docker version # View version information docker info # Displays the system information of docker, including the number of images and containers docker command --help # Help command
-aq represents a set of - all [all] and - quiet [display id ONLY]
Mirror command
[root@VM_0_5_centos ~]# docker images # View all mirrors REPOSITORY TAG IMAGE ID CREATED SIZE hello-world latest feb5d9fea6a5 4 weeks ago 13.3kB # explain REPOSITORY Mirrored warehouse source TAG Mirrored label IMAGE ID image id CREATED Creation time of the image SIZE Mirror size docker images -q # Show ID ONLY
Search image docker search
docker search mysql # Search mysql image docker search mysql --filter=stars=3000 search mysql More than 3000 image collections
Download Image docker pull
Download images can also be queried through the website: https://hub.docker.com/_/redis
[root@VM_0_5_centos ~]# docker pull redis # Download the redis image. The latest version is downloaded by default Using default tag: latest latest: Pulling from library/redis 7d63c13d9b9b: Pull complete # Layered Download: if you have downloaded the same file before, you can share it. Divide a file into several files, similar to rar volume compression a2c3b174c5ad: Pull complete 283a10257b0f: Pull complete 7a08c63a873a: Pull complete 0531663a7f55: Pull complete 9bf50efb265c: Pull complete Digest: sha256:a89cb097693dd354de598d279c304a1c73ee550fbfff6d9ee515568e0c749cfe # autograph Status: Downloaded newer image for redis:latest docker.io/library/redis:latest # The real address docker pull redis is the same as docker pull docker.io/library/redis:latest docker pull redis:5.0 # Download the specified version of redis
Delete image docker rmi
docker rmi -f $(docker images -aq) Delete all mirrors docker rmi -f 02fee89f17ad # Deletes the image with the specified id
View mirror construction history
docker history image id
Container command
explain
A container can only be created with an image; So download a centos system first
docker pull centos
Create a new container and start
# Create a container based on the image and start the container into the container docker run --name contos_3 -p 9090:80 -it centos /bin/bash # Parameter description --name cname The name of the container, if not configured, docker Will automatically give you a name -d Run in background mode -it Run interactively -p (a lowercase letter p)Specifies the port of the container -p ip:Host port:Container port -p Host port:Container port -p Container port Container port -P (Capitalize P)Random mapping port /bin/bash After entering the container, open a new terminal
Delete after use -- rm
When we finish the test, there is no problem. At this time, we need to delete the container. It will be troublesome to delete it manually every time, so docker gives a parameter - rm, which can delete the container when stopping the container. The usage is as follows
# The official usage of tomcat, which is generally used on Tomcat docker run -d --rm centos # When you stop docker by running the following command, the container will be deleted docker rm -f container id/Container name
Common pit
When running in the background through the following commands, it is found that centos is not lucky. This is because to make the container run in the background, there must be a foreground process. If docker finds that there is no application, it will automatically stop; Like nginx, when the container starts and finds that it does not provide services, it will stop immediately;
# This command stops the container dockers run -d centos # The following command does not stop the container because there is a foreground process dockers run -d -it centos
How to connect overnight hosts and containers (flowchart)
When creating a new container, there is a very important parameter - p 8080:80. This parameter is used by the overnight host and container. That is, when we access localhost:8080 externally, we actually access port 80 of the container. The complete command for creating a new container is as follows
docker run -p 9090:80 centos
Open multiple ports
A server like tomcat has three open ports, namely 8080, 8005 and 8009. What should we do if we want to open these ports? In fact, it is very simple. You only need to configure multiple - PS
docker run -d -p 8080:8080 -p 8005:8005 tomcat
Exit container
eixt # Note: This is to stop the container directly ctrl + P + Q Shortcut keys can return to the main system, but do not exit the container
Start or stop the container
docker start container id # To start a container, you can only start a container that has already been created docker restart container id/Container name # Restart container docker stop container id/Container name # Stop container docker kill Allow id/Container name # Force stop container
View all containers
docker ps -a # View the containers that have been run- a means - all (all)
View running containers
docker ps # View all running containers
Enter a running container
# Method 1: open a new terminal after entering the container docker exec -it container id/Container name /bin/bash # Mode 2: use the executing terminal after entering the container docker attach container id/Container name
Delete container
It should be noted that,
docker rm container id/Container name # Delete the specified container. You cannot delete a running container docker rm -f container id/Container name # Deleting a specified container can also delete a running container docker rm $(docker ps -aq) # Delete all containers. You cannot delete a running container docker rm -f $(docker ps -aq) # Delete all containers, including running containers
view log
docker logs -f -t --tail 10 container id
# explain
-f Tracking log output will always display the latest log content; and tail -f Is the same;
-t Print timestamp
--tail 10 Only 10 lines are displayed
Viewing processes in a container
docker top container id/Container name
View metadata for container
docker inspect container id/Container name
Copy the files in the container to the host
docker cp container id/Container name:In container host path
View container status command
docker stats
The display contents are as follows
CONTAINER ID NAME CPU % MEM USAGE / LIMIT MEM % NET I/O BLOCK I/O PIDS c75c62eff5f6 tomcat_1 0.16% 126.3MiB / 1.796GiB 6.87% 28.4kB / 233kB 20MB / 0B 29 # explain CONTAINER ID container id NAME Container name CPU % CPU Utilization rate MEM USAGE How much memory is used LIMIT Total memory MEM % Memory usage, showing memory usage as a percentage NET I/O network I/O data BLOCK I/O disk I/O data PIDS process id
Commit image commit the current container generates a new image
docker commit -a="author" -m="explain" -p container id/Container name mirror new name:Mirror version
# For example, make the current tomcat container to generate an image
docker commit -a="yexindong" -m="First made image" tomcat_1 mytomcat:1.0
# Parameter description
-a :Submitted image author;
-c :use Dockerfile Command to create an image;
-m :Explanatory text at the time of submission;
-p :stay commit Pause the container when.
Mount - v
After running the following command, the local directory will be mounted on the container directory, the corresponding directory will be automatically created on the container and host computer, and the files created or modified under the directory will be automatically synchronized;
docker run -d -v Host Directory:Container directory tomcat
If you need to mount multiple directories, you only need to configure multiple - v
docker run -d -v Host Directory:Container directory -v Host Directory:Container directory tomcat
Configure container environment variable - e
e is the abbreviation of environment,
The following is how to set the initial password for mysql: 123456
docker run -d -e MYSQL_ROOT_PASSWORD=123456 mysql:5.7
The first way: you can view the environment variables that have been configured in the container in the following ways
docker exec "Container name or container id" env
The second method: check through inspect and find that the Env item is the environment variable- A 10 means to print the last 10 lines
docker inspect container id/Container name | grep Env -A 10
give the result as follows
"Env": [
"PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"
],
Image saving and loading
If you need to send your own image to others and don't want to share it through the warehouse, you can use the function of image saving,
Mirror save
First, we save the image to the local disk as a file
docker save image id/Image name -o /Local directory/File name # Like this docker save ad8a585d32e3 -o /root/dockerFile/xx.tar # After running, you can see that the file has been saved successfully [root@VM_0_5_centos dockerFile]# ll total 356440 -rw------- 1 root root 364991488 Oct 28 18:45 xx.tar
Load saved image
Use the load command to load and see the following contents, indicating that the image has been loaded successfully
[root@VM_0_5_centos dockerFile]# docker load -i /root/dockerFile/xx.tar 2fefb3e7f055: Loading layer [==================================================>] 47.6MB/47.6MB 8b589f61fd94: Loading layer [==================================================>] 58.82MB/58.82MB 753a6b1d88c8: Loading layer [==================================================>] 19.99MB/19.99MB Loaded image ID: sha256:ad8a585d32e34b301aab4b278704a908f6eca53884fd531a79859dd6054a22ae
Next, let's see that the image has been loaded, but it hasn't been named yet
[root@VM_0_5_centos dockerFile]# docker images REPOSITORY TAG IMAGE ID CREATED SIZE <none> <none> ad8a585d32e3 2 hours ago 356MB
Next, use the tag command to give the image a name and version number
[root@VM_0_5_centos dockerFile]# docker tag ad8a585d32e3 xindong_tomcat_2:1.0 # Looking at the image, it already has a name [root@VM_0_5_centos dockerFile]# docker images REPOSITORY TAG IMAGE ID CREATED SIZE xindong_tomcat_2 1.0 ad8a585d32e3 2 hours ago 356MB
Execute commands within the container on the host
docker exec -it container id/Container name command to execute # For example, I want to view the network card in the container docker exec -it tomcat_01 ip addr
Network command network
View all local docker networks
docker network ls
Create a network - driver is the network mode, - subnet is the subnet mask, followed by / 16 indicates that more than 60000 IPS can be generated, and - gateway is the gateway address
docker network create Network name --driver bridge --subnet 192.168.0.1/16 --gateway 192.168.0.2 mynet
Join container to current network
docker network connect Network name container name
Disconnect the network of the container (the container must be running to disconnect)
docker network disconnect Network name container name
View network details
docker network inspect network id/Network name
Delete network
docker network rm network id/Network name
Delete all unused networks
docker network prune --f