Docker Network External vs Internal: Simplified 3-Minute!

Docker provides multiple network drivers out-of-the-box but let’s explore the difference and when to use “Docker Network External vs Internal“

Understanding Docker Networks

Docker runs your application as a container in a single unit making it easy to manage.

When you run the Docker application you run multiple containers such as a web server, database server, and application layer, therefore efficient communication is crucial. Choosing the right Docker network is key to communicating between the container and the outside world.

Docker offers two main network options:

1. Default Bridge Network

This default Docker network comes pre-configured when you run the containers and connect them to the host network. A Bridge Network is most commonly used to enable communication with other containers on the same host.

2. User-Defined Network

Apart from the default bridge network, Docker provides the flexibility to create a custom network with assigned names and connect specific containers. This allows for isolated communication and restricted access to external resources.

Docker Network Overlay vs Bridge – Ultimate Difference

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Docker Network External vs Internal

Let’s explore the two main types of user-defined networks

External Networks

External networks allow containers to connect to the outside world.

Docker Network External vs Internal - External Network Diagram

When to use External Netowks

• Your container needs to access external services like databases, APIs, or other applications running outside of the Docker environment

• You want your containers to be accessible from the host machine.

• You want your container to be accessible from the internet with proper security.

Communication

Containers in the external network can communicate with each other on the same network as the Docker host. This allows them to access external resources and services from the container.

Let’s say you have MYSQL DB running on a Docker host and a Python application running inside the Docker container, the external network can allow communication in between.

Internal Networks

Internal networks allow containers to connect and communicate securely within.

Docker Network External vs Internal: internal Network Diagram

When to use Internal Netowks

• You want secure and isolated communication between containers.

• Excellent choice for the microservice architecture.

• When you want containers to talk with each other but not directly to the outside world.

Isolated Communication

Containers in an internal network can only communicate within the same network, provide network isolation, and enhance security.

Since the service running on the Host or external side can’t communicated this prevents unauthorized access.

Service Discovery

Docker provides the built-in DNS resolution for running containers on the same network. Each container can resolve and discover the other containers with the name.

If you have a multi-tier web application name web and db on the same network, a web container can connect to a Database using db as hostname without remembering the IP address.

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Docker Network External vs Internal: Difference

Let’s explore the comparison for Docker Network External vs Internal:

Docker Network External vs Internal: Difference

Choosing the Right Network for Your Needs

The choice between “Docker network external vs internal” depends on your application architecture and requirements:

Do your containers need external access?

If your container needs to connect with the database, API, or the internet then an external network is the best choice.

My containers act as microservices, only communicating with each other with no external access

An internal network is the perfect choice. Provide secure, isolated communication for your microservices.

My application connects a containerized database that other containers need to interact with

Both the database and the application containers need access, so they should be connected to the same external network.

I want my web application container to be accessible from the internet

An external network is suitable. You can explore the required ports only for the application to work. Check the Docker container security checklist

Conclusion

Understanding the Docker network external vs internal - allows you to create and choose an efficient network for your container application.

You can also check other Docker network drivers such as Docker Network Overlay vs Bridge

Key Takeaways:

• Docker networks enable communication between containers.
• External networks allow containers to access external resources.
• Internal networks provide secure, isolated communication within the same network.
• Use the service discovery to simplify communication.
• Secure your containers by minimizing exposed ports.

Refer to the Official Docker documentation for detailed instructions on creating and managing networks.

Additional Links

Find Docker Which Network is Container Using

Docker Compose Network Name Without Prefix – 3 Easy Tricks

Docker Network Overlay vs Bridge – Ultimate Difference