rungo

rungo is a simple, lightweight CLI tool for creating and running containers - AKA a container runtime. This project was created for experimenting with containers internals and better grasp the concepts of containerization.

Features

• Mount namespace
• UTS namespace
• IPC namespace
• Network namespace
• PID namespace
• User namespace
• Cgroups

Installation

go build -o rungo cmd/main.go

Usage

Usage: ./rungo -run -uid [-mnt=/path/rootfs] [-uts [-hostname=new_hostname]] [-ipc] [-net] [-pid] [-command command]
  -mnt='/path/rootfs'           Enable Mount namespace
  -uts                          Enable UTS namespace
  -hostname='new_hostname'      Set a custom hostname into the container
  -ipc                          Enable IPC namespace
  -net                          Enable Network namespace
  -pid                          Enable PID namespace
  -uid                          Enable User namespace
  -command='command'            Command to run "/bin/sh" by default

Examples

# Run a container with a custom hostname
./rungo -run -uid -uts -hostname=container1

# Run a container with a custom hostname and a custom command
./rungo -run -uid -uts -hostname=container1 -command=/bin/ls

# Run a fully isolated container
./rungo -run -uid -uts -ipc -net -pid -mnt=/path/rootfs

The rootfs directory can be created with the following command:

mkdir rootfs

Then, you can populate the rootfs directory with the following command:

docker export $(docker create busybox) | tar -C rootfs -xvf -

Demo

amit@amit-vm:~/rungo$ ./rungo -run -uid -uts -pid -mnt=/tmp/rootfs -net -ipc -command=/bin/sh -hostname=rungo
INFO[0000] Initiating container process!                
INFO[0000] Setting PID namespace                        
INFO[0000] Setting IPC namespace                        
INFO[0000] Setting NET namespace                        
INFO[0000] Setting USER namespace                       
INFO[0000] Setting MOUNT namespace
INFO[0000] Setting UTS namespace
🧙 [root@rungo] ~/ ‣ ps
PID   USER     TIME  COMMAND
    1 root      0:00 /proc/self/exe -ns -uid -uts -pid -mnt=/tmp/rootfs -net -ipc -command=/bin/sh -hostname=rungo
    6 root      0:00 /bin/sh
   10 root      0:00 ps
🧙 [root@rungo] ~/ ‣ 

References

• Namespaces in operation, part 1: namespaces overview
• containers-from-scratch-with-golang
• Gontainer