Docker networking

Docker networking refers to the way Docker containers communicate with each other and with other network resources. Docker provides several networking options to facilitate communication between containers, between containers and the host system, and between containers and external networks. Some common Docker networking concepts and features include:

Create a ec2 instance and connect it through ssh key-pair . now, install docker on ec2 instance:

sudo apt-get update

sudo apt-get install docker.io -y

ip address show

It appears that you encountered a "permission denied" error while trying to run docker ps. This error occurs because the user running the docker command does not have permission to access the Docker daemon socket (/var/run/docker.sock), which is required for communicating with the Docker engine.

To resolve this issue, you used the sudo chown $USER /var/run/docker.sock command to change the ownership of the Docker socket file to the current user. By doing this, you granted the current user permission to access the Docker daemon socket.

After changing the ownership of the Docker socket, you were able to run docker ps successfully, as the current user now has the necessary permissions to communicate with the Docker daemon and retrieve information about running containers.

It's worth noting that while changing the ownership of /var/run/docker.sock to the current user resolves the permission issue, it's also important to consider the security implications of granting such access, as it allows the user to control Docker containers, which could potentially lead to security risks if misused.

docker network ls

To provide network access to your Nginx container so that it can interact with the external world, you have several options depending on your networking requirements.

here's a breakdown of the types of Docker networking:

1. Default Bridge Network:

   • The default bridge network is created automatically by Docker when you install it. Containers connected to this network can communicate with each other using IP addresses. Docker assigns IP addresses from a pre-configured private range to containers on this network.

     

     To expose a port from your Docker container so that it can external world can connect to docker nginx conatiner, typically use the -p flag when running the container. Here's how you can do it:

     1. Run Nginx Container with Exposed Port: Start your Nginx container with the -p flag to expose a port from the container to the host machine:

        docker run -d --name mynginx -p 80:80 nginx

In this command:

• -d: Runs the container in detached mode (in the background).

• --name mynginx: Assigns a name to the container.

• -p 80:80: Publishes port 80 from the container to port 80 on the host. The format is -p <host-port>:<container-port>.

• nginx: Specifies the Nginx image to use.

Now, your Nginx container is running, and port 8080 on your host machine is forwarded to port 80 on the Nginx container.

go to public_ip of ec2:80

• 

1. Host Network:

   • With host networking, containers share the network namespace with the Docker host and no need to publish port. Containers bypass Docker's network abstraction and directly use the host's network stack. This can provide better performance as there is no additional NAT (Network Address Translation) overhead.

     

     

     

2. Custom Bridge Network (User Defined Network):

   • Users can create custom bridge networks with specific configurations using Docker commands or Docker Compose.

     This allows containers to communicate with each other on the same network. Users can specify the subnet, gateway, IP range, and other settings for the custom bridge network.

Now, theses nginx-custom1 and nginx-custom2 can communicate with each other because they are in same network.

1. None Network:

   • The none network mode disables all networking for the container.

   • This mode is useful for containers that don't need network access, such as batch processing or offline tasks.

     

     

2. Overlay Network:

   • Overlay networks are used in Docker Swarm mode for communication between containers across multiple Docker hosts.

   • They facilitate communication and service discovery in distributed environments.

   • Overlay networks use VXLAN (Virtual Extensible LAN) encapsulation to connect containers across hosts.

     docker network create --driver overlay my-overlay-network

3. Macvlan Network:

   • Macvlan allows containers to have their own MAC addresses and appear as physical devices on the network.

   • Each container connected to a Macvlan network can have its own IP address on the external network.

   • This is useful for scenarios where containers need to be directly accessible on the network.

4. IPvlan Network:

   • IPvlan is similar to Macvlan but operates at the IP layer.

   • Each container in an IPvlan network gets its own IP address on the external network.

   • IPvlan can be more efficient than Macvlan in certain scenarios.

Thank you for taking the time to read this article. I hope you found it informative and helpful.