README.md

Create a container with a Bash script

This repo contains a script to create a basic Linux container using Bash. The steps include configuring Linux cgroups, creating network namespaces, and setting up a root filesystem. Executing the script will create the container and start an interactive shell inside it.

Functionalities

Here is a breakdown of the create.sh script functionalities:

1. Create Filesystem: Downloads and extracts the Alpine Linux miniroot filesystem into /mnt/mycontainer. Creates a /proc directory inside the container's filesystem.
2. Set Up cgroups: Creates a cgroup named mycontainer for memory and CPU.
3. Set Up Network Namespace:
   • Creates a network namespace called mycontainer_ns.
   • Creates a virtual Ethernet (veth) pair, veth0 and veth1.
   • Assigns veth1 to the mycontainer_ns namespace.
   • Configures IP addresses for veth0 and veth1.
4. Run unshare within the network namespace to create a new mount namespace, a new PID namespace, and mounts the proc filesystem, then chroots into the container's filesystem and starts a shell.

Demo

This script essentially sets up a basic containerized environment with network isolation and a separate process namespace. The demo also shows the network communication from container to host and vice versa, this is done with the veth configuration in create.sh.

Prerequisites

1. Linux machine with kernel version >= 5.8
2. libcgroup-dev and debootstrap

Install the following

sudo apt update && sudo apt upgrade -y
sudo apt install -y libcgroup-dev debootstrap

Quickstart

To create the container

sudo ./create.sh

To delete the container

sudo ./delete.sh