03. Containers Connection

Port Mapping

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

Interpretation

• -P: map to a random local port
• -p: map to a specific local port

View Port Mapping

docker port <container> 5000

Containers Connection

Create network

docker network create -d bridge test-net

Interpretation

• -d: specify the net type (bridge/overlay)

Connect Container

Run a new container and connect to network test-net

docker run -itd --name test1 --network test-net ubuntu /bin/bash
docker run -itd --name test2 --network test-net ubuntu /bin/bash

Now the test1 and test2 can connect each other.

Config DNS

Add configuration to /etc/docker/daemon.json .

{
  "dns": [
    "114.114.114.114",
    "8.8.8.8"
  ]
}

Using the follow command to view the DNS info
docker run -it --rm ubuntu cat etc/resolv.conf

Specify DNS for container

docker run -it --rm -h host_ubuntu --dns=114.114.114.114 --dns-search=test.com ubuntu

Interpretation

• --rm: The file system will clean up when exit a container
• -h Hostname: set the container system name, the name can be write to /etc/hostname and /etc/hosts.
• --dns=IP_ADDRESS: add dns to /etc/resolv.conf
• --dns-search=DOMAIN: set the container search domain.

Reference

Tutoriaspoint