After docker is deployed, mysql cannot connect

1. Create instance command
docker run -id --name=c_mysql -p 3306:3306 -v /docker/mysql/data:/var/lib/mysql -e MYSQL_ROOT_PASSWORD=123456 mysql:5.6.37
2. View the launched instance docker ps

3. The port 3306 of the host is mapped here, I have opened the port

4. Connect on the host machine

#This error is like mysql does not exist, check if mysql is started

#mysql has been started, and the port is not occupied
5. It has been tested in the container, mysql can be connected normally; try to open the root user to access from any host
5.1, enter the container, and connect to mysql
docker exec -it c_mysql bash
mysql -uroot -p123456
5.2. Open the root user to all hosts to access
mysql> grant all privileges on . to [email protected]'%'; #Authorization
mysql> flush privileges; #Refresh the privilege table
6. Run the connection test again in the host

#Still not working!!!
7. I went to Baidu and thought that the host's routing was not enabled. Let's try it.
#Come back and find that the problem lies in the host, because if you want to use the mysql command, you must have /usr/This command is available in the bin/ directory.But I installed mysql in docker, so the host cannot use mysql to connect to the docker database. The error reported when using the remote tool navicat to connect should be that the root user is not enabled, and any host can access it.Since the above has been opened, I now test that navicat can be connected remotely

8. The above mentioned a host routing problem. If we do not open the routing, the host will be isolated from the container instance network, so it is necessary to open it.
8.1. Check if the route is open
sysctl net.ipv4.ip_forward

#The return value of 1 means the route is enabled, and 0 means it is not enabled
8.2, enable the route
echo “net.ipv4.ip_forward = 1” >>/etc/sysctl.conf#Write the command to the /etc/sysctl.conf file
sysctl -p #Load the kernel
sysctl net.ipv4.ip_forward #Check whether the route is enabled again

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