Docker dynamically exposes ports to containers

View the IP address of the Container

docker inspect <container name or id>| grep IPAddress

View the mapped port of the Container

docker port <container name or id>
eg.
docker port d8dac7399647
docker port hfq-jedi-zxf-eden

Use iptables to view container mapping

iptables -t nat -nvL

iptables -t nat -nvL --line-number

Example of adding a new port mapping

##Map host port 31101 to container port 6379

iptables -t nat -A PREROUTING -p tcp -m tcp --dport 31101 -j DNAT --to-destination 192.168.42.2:6379

Save iptables rules

iptables-save

illustrate

192.168.42.2 is the result of docker inspect <container name or id>| grep IPAddress

After the port mapping is completed, the result cannot be queried through docker port d8dac7399647

Can be

iptables -t nat -nvL | grep 192.168.42.2

Query mapping relationship

Additional knowledge: Mechanisms in Docker container communication and port exposure issues

The link method has always been used for communication between Docker containers. This limits the order in which each container is started, which always feels inflexible. Therefore, this time we explored accessing containers directly through the LAN allocated by the Docker's own network card.

Docker port exposure means forwarding the port service of the container itself to the exposed port through the forwarding of the docker0 network card, for example, executing:

docker run -dit -p 8080:12345 --name=container_name image_name

When accessing using the 172.17.0.x local area network assigned by the docker0 network card, use port 12345. When using 192.168.1.x or other local public IP to access, you need to use 8080 to access

Time is limited, so I won't analyze it in detail for now. I'll analyze it with pictures when I have time.

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