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Gophernetes

Gophernetes is a minimal, educational container runtime written in Go. It is designed to illustrate some of the fundamental principles behind containerization, including process isolation with namespaces, control groups, and filesystem isolation.

Features

  • Namespaces: Gophernetes creates new namespaces (PID, UTS, NS, NET) for the container, providing isolation from the host.
  • Chroot: Gophernetes uses the chroot system call to change the apparent root directory for the current running process and its children.
  • Mount: Gophernetes mounts a proc filesystem for the container in a new mount namespace.
  • Control Groups: Gophernetes limits the memory usage of the container through cgroups.
  • Networking: Gophernetes sets up a basic virtual ethernet networking stack inside the container using a separate network namespace.

Usage Of go App

First, build the Go application:

go build -o gophernetes

Then, use the gophernetes binary to start a new container:

sudo ./gophernetes run /bin/bash

You will be dropped into a new shell running inside the container. From this shell, you can run commands isolated from the host.

The binary accepts commands in the following format:

./gophernetes [run | child] command [arguments...]
run: This starts a new container and runs the provided command. The run command should be followed by the command to run inside the container, for example /bin/bash.
child: This is an internal command used by gophernetes to start the isolated process inside the new namespaces.

Building the Docker Image

You can build a Docker image for Gophernetes with the provided Dockerfile:

docker build -t gophernetes .

You can then run Gophernetes inside a Docker container. However, due to the nature of the operations it's performing (like creating namespaces, setting up network interfaces, etc.), it requires privileged permissions to work properly:

docker run --privileged -it gophernetes run /bin/bash

Script Gophernetes

Gophernetes is a simple bash script for managing containers using containerd as the container runtime.

Usage of spript bash

 ./gophernetes COMMAND [OPTIONS]

Commands using the spript bash

  • run <source> <image> <name>: Pull an image from a source and run a container with the given name.
  • pause <name>: Pause a running container.
  • resume <name>: Resume a running container.
  • rm <name>: Remove a container.
  • logs <name> [--live]: Fetch and display logs of a container. Use the --live flag to display live logs.
  • exec <name> <command>: Execute a command in a running container.
  • pull <source> <image>: Pull an image from a source.
  • list [--all|--images]: List all containers. Use the --all option to list all containers, or --images to list image containers.
  • network create <name>: Create a network.
  • network delete <name>: Delete a network.
  • attach <name> <network>: Attach a container to a network.
  • help: Show help menu.

Examples

# Run a container from Docker Hub
./gophernetes run docker alpine alpine-container

# Run a container from a local tar file
./gophernetes run local my_image.tar my-container

# Stop a container
./gophernetes stop my-container

# Remove a container
./gophernetes rm my-container

# Fetch and display logs of a container
./gophernetes logs my-container

# Execute a command in a running container
./gophernetes exec my-container "ls -l"

# Pull an image from Docker Hub
./gophernetes pull docker alpine

# List all containers
./gophernetes list

# Create a network
./gophernetes network create my-network

# Delete a network
./gophernetes network delete my-network

# Attach a container to a network
./gophernetes attach my-container my-network

# Show help menu
./gophernetes help
Requirements
containerd runtime with the appropriate socket path configured.

Warning

Please note that Gophernetes is a minimal, educational container runtime. It is not feature-complete and is not intended for production use. Features like container image downloading, advanced networking, and resource isolation are either simplified or missing.

License

Gophernetes is open-source software licensed under the MIT license.

Additional Features:

In terms of features, this is a pretty solid basic implementation of a container runtime. Here are some additional features you could consider adding:

  1. Container Image Support: Right now, the application assumes that the necessary file system (rootfs) is available on the host. Adding support to pull and unpack container images from a Docker registry would make this a more self-contained tool.

  2. Better Networking: Right now, the network setup is quite rudimentary. You could look into how Docker sets up advanced networking, with a virtual ethernet bridge, NAT and IPTables rules.

  3. Isolation for Other Resources: Right now, we're only limiting memory usage. You could add similar limitations for CPU, block I/O, etc.

  4. Better Error Handling: Right now, we're ignoring all errors from the setupNetwork and limitMemory functions. These operations can and will fail in many scenarios, and we should handle these errors appropriately.

Please remember that these are all advanced features that involve quite a bit of additional complexity. I would recommend you to thoroughly understand the existing code and concepts before attempting to add these.