Lesson 7 - Docker Networking

15/02/2024 - 2 phút

Docker Networking is an indispensable part of deploying containerized applications, facilitating the creation of interconnected and communicative environments between containers. To gain a deeper understanding of Docker Networking, let’s explore the steps to configure networks and some real-world scenarios you might encounter.

Docker Network Types

Docker provides several basic network types:

bridge: The default network bridge for containers. Containers within the same bridge network can communicate with each other through IP addresses.
host: Removes the network isolation between the container and the Docker host, allowing the container to use the host’s network stack.
overlay: Creates a network across multiple Docker daemons, suitable for distributed applications across several hosts.
macvlan: Allows assigning a MAC address to a container, making it appear as a physical device on the network.

Step 1: Configuring a Custom Bridge Network

Create a Bridge Network:
```
docker network create --driver bridge my_custom_network
```
This command creates a new bridge network named my_custom_network.
Run Container and Connect to Custom Network:
```
docker run -d --name my_container --network my_custom_network nginx
```
The my_container will run and automatically connect to my_custom_network.

Step 2: Container Communication

Linking Containers:

docker run -d --name db_container --network my_custom_network mysql
docker run -d --name app_container --network my_custom_network --link db_container:db my_app

app_container will link to db_container using the alias db, allowing app_container to communicate with db_container using this alias.

Step 3: Exposing and Port Mapping

Expose Container Externally:
```
docker run -d --name web_container --network my_custom_network -p 8080:80 nginx
```
This command maps port 80 of web_container to port 8080 on the Docker host, allowing external access to web_container through the host’s port 8080.

Step 4: Using Docker Compose

Docker Compose makes it easier to manage complex containers and networks. Here is an example of a docker-compose.yml file to configure networks and services:

version: '3.8'
services:
  web:
    image: nginx
    ports:
      - "8080:80"
    networks:
      - my_app_network

  db:
    image: mysql
    environment:
      MYSQL_ROOT_PASSWORD: example
    networks:
      - my_app_network

networks:
  my_app_network:
    driver: bridge

This file defines a bridge network my_app_network and two services web and db connected to this network.

Conclusion

Docker Networking provides flexibility and power in how containers communicate and are managed. Understanding the different types of networks and knowing how to use them in specific scenarios is key to building and deploying efficient, secure applications in a containerized environment. Don’t forget to leverage tools like Docker Compose for easier and more efficient Docker project management.