05A - Docker Networking

Docker Networking Options

• The --network none option completely isolates a container, preventing it from accessing any network during execution.
• Port forwarding is necessary in Docker containers when exposing services running inside containers to the outside world, enabling external access via specific ports.

Bridge Network and Port Forwarding

• The bridge network in Docker allows multiple containers to communicate with one another, acting as a virtual switch, while also facilitating port forwarding through the host.
• Port forwarding is not needed in the host network mode because containers use the host's network stack directly, meaning they can access the host's ports without any additional configuration.

Port Forwarding Syntax

• The -p 8080:80 command in docker run maps port 80 in the container to port 8080 on the host, allowing external traffic on 8080 to be routed to the container's service on port 80.

Bridge Network Purpose and Creation

• A bridge network serves as a private internal network for Docker containers, enabling communication and resource sharing without exposing them to the external network.
• To create a custom bridge network, the command docker network create <network_name> is used.

Connecting Containers to Networks

• The command docker network connect <network_name> <container_name> connects an existing container to a specified bridge network.

Host Network Characteristics

• The host network mode allows containers to share the host's IP address and networking stack, providing direct access to the host's ports for service exposure.
• In host network mode, containers indeed have direct access to all ports on the host, leading to potentially simpler configurations for services like web servers.

Communication Between Containers

• Containers on a bridge network can communicate with one another through their internal IP addresses assigned by Docker, facilitating inter-container communication without needing port forwarding.

Container Network Connection during Startup

• When running a container, the --network <network_name> flag can be used to connect it to a specific bridge network at the time of execution.

Ideal Network for Web Servers

• The host network type is ideal for running web servers that require direct access to the host's IP address and ports, streamlining connection configurations.

Additional Network Options

• The 'None Network' option disables all networking features for a container, isolating it completely.
• Sharing of host resources occurs when using the host network stack, where containers utilize the host's network settings directly.

Starting a Container on Host Network

• The command docker run --network host nginx starts a container using the host network stack directly from the NGINX image.

Effects of Attachment to Bridge Networks

• When a container is attached to a specific bridge network in Docker, it can communicate with other containers on that same network, while remaining isolated from others.

Learn about Docker networking, including how to create custom networks using the docker network create command. Discover how custom networks provide more control over network settings and enable inter-container communication. Explore how containers on the same network can communicate with each other and how port mappings allow external access.