How to assign domain names to containers in Docker?

Assigning domain names to Docker containers typically involves several steps, utilizing Docker's built-in features and third-party tools. Here are some common methods and steps:

1. Using Docker Networks

Steps:

1. Create a user-defined network: This allows containers to discover each other by name, rather than solely by IP address.

bash
docker network create my-network

1. Specify the network and alias when starting the container:

bash
docker run --network my-network --name my-container-name --hostname my-domain-name my-image

Here, the --hostname parameter sets the container's domain name, while --name sets the container's name.

Example:

Suppose you want to set the domain webapp.local for your web application:

bash
docker network create app-network
docker run --network app-network --name web-container --hostname webapp.local my-web-app-image

2. Using Docker Compose

If you use Docker Compose, you can configure the network and domain name in the docker-compose.yml file.

docker-compose.yml Example:

yaml
version: '3'
services:
  web:
    image: my-web-app-image
    hostname: webapp.local
    networks:
      - app-network

networks:
  app-network:
    driver: bridge

3. Using Third-Party Tools, such as Traefik

Traefik is a modern HTTP reverse proxy and load balancer that can easily implement service discovery and dynamic routing.

Steps:

1. Set Traefik as the frontend proxy.
2. Configure Traefik to automatically discover Docker services.

docker-compose.yml Example:

yaml
version: '3'

services:
  reverse-proxy:
    image: traefik:v2.3
    command: --api.insecure=true --providers.docker
    ports:
      - "80:80"
      - "8080:8080"
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock

  web:
    image: my-web-app-image
    labels:
      - "traefik.http.routers.web.rule=Host(`webapp.local`)"

Summary

Assigning domain names to containers in Docker can be achieved through various methods. The most straightforward approach is to use Docker's built-in networking features by setting the --hostname parameter. For more complex scenarios, Docker Compose or third-party tools like Traefik can be used for advanced configuration. These methods not only help you better organize and manage containers but also enhance the scalability and maintainability of your applications.