Detailed explanation of Docker basic network configuration

External Access

Randomly map ports

Using the -P flag, Docker will randomly map a port between 49000 and 49900 to the network port exposed inside the container. docker run -d -P training/webapp python app.py
docker ps -l # Display the most recently created container docker logs -f web # View application information

Map all interface addresses

docker run -d -p 5000:5000 training/webapp python app.py

Maps to the specified port of the specified address

docker run -d -p 127.0.0.1:5000:5000 training/webapp python app.py

Map to any port of the specified address

docker run -d -p 127.0.0.1::5000 training/webapp python app.py

Specify UDP port

docker run -d -p 127.0.0.1:5000:5000/udp training/webapp python app.py

View the mapped port configuration

docker port web 5000

Create a new docker network

docker network create -d bridge my-net

Run the container to connect to the newly created my-net network

docker run -it --rm --name busybox1 --network my-net busybox sh
docker run -it --rm --name busybox2 --network my-net busybox sh

View container information

docker container ls
Ping test in container to see if containers are connected

Docker Compose is recommended for interconnecting multiple containers

Configure DNS After the host DNS information is updated, the DNS configuration of all Docker containers is immediately updated through /etc/resolv.conf

Configure DNS for all containers

vim /etc/docker/daemon.json add content {
 'dns':[
  "114.114.114.114",
  "8.8.8.8"
 ]
}

docker run -it --rm ubuntu:17.10 cat /etc/resolv.conf

Container interconnection

The container's connection system is another way to interact with applications in the container in addition to port mapping.

It creates a tunnel between the source and receiving containers, and the receiving container can see the information specified by the source container.

Custom container name

The connection system is executed based on the name of the container, so you need to customize a relatively simple and easy-to-distinguish container name.

Custom naming uses the --name parameter, which has been encountered in previous articles:

docker run -d -p --name db mysql

Container names must be unique.

When executing docker run, if you add the --rm parameter, the container will be deleted immediately after termination. However, it cannot be used together with the -d parameter.

Container interconnection

Use the --link parameter to establish a secure connection between containers for interaction.

Here is an example:

First create a database container:

docker run -d --name db training/postgres

Then create the web container:

docker run -d -P --name web --link db:db training/webapp python app.py

At this point, the db container and the web container are interconnected.

--link parameter: --link name:alias, name is the name of the container to be connected, and alias is the alias of this connection.

You can use docker ps to view container information, where the names column can show the status of the interconnection.

Docker establishes a secure tunnel between two interconnected containers, eliminating the need to map their ports to the host and preventing port exposure.

Docker exposes connection information in two ways:

• Environment variables
• Update /etc/hosts file

Use the env command to view the environment variables of the web container just now:

docker run --rm --name web2 --link db:db training/webapp env ...

The environment variables starting with DB_ are used by the web container to connect to the db container, and are prefixed with an uppercase connection alias.

In addition to environment variables, Docker also adds the host information to the parent container's /etc/hosts file. The web container uses its own ID as the default host name, and the db container uses db as the host name.

For example, in the case of multiple web to db containers, you can link multiple child containers to the parent container.

The above is the full content of this article. I hope it will be helpful for everyone’s study. I also hope that everyone will support 123WORDPRESS.COM.