Shocker

Docker implemented in shell. Forked from bocker.

• Features
• Usage
• Installation
• Prerequisites
• FAQ
• License

Features

• process isolation using cgroups, iptables, chroot and namespaces(7)
• advanced control over network with port forwarding
• strong focus on usability
• transparent codebase written in modern POSIX shell

Usage

  Usage: shocker [options] <command>
 
  Commands:
    list           # list containers
    start          # start a container
    change         # modify a container
    stop           # stop a container
    remove         # remove a container
    image list     # list images
    image pull     # fetch a remote image
    image create   # create an image
    image change   # modify an image
    image remove   # remove an image
 
  Options:
    -h, --help     output usage information
    -v, --version  output version information
 
  Examples:
    $ shocker image pull -h              # output usage for the pull command
    $ shocker image pull alpine@latest   # fetch alpine linux from docker
    $ shocker image list                 # list local images
    $ shocker start img_1235 ash         # start an ash shell from an image
    $ shocker change img_1235 -n beep    # rename a container
    $ shocker change beep -m 500m        # change a container's memory limit
    $ shocker list                       # list containers
    $ shocker stop beep                  # stop a running container
    $ shocker remove beep                # remove a stopped container
    $ shocker image remove img_1235      # remove a local image

Installation

$ curl -sL https://github.com/stamf/shocker/archive/master.tar.gz | tar xz

Prerequisites

The following packages are needed to run shocker.

• btrfs-progs (btrfs-tools on Ubuntu)
• curl
• iproute2
• iptables
• libcgroup-tools (cgroup-tools on Debian / cgroup-bin on Ubuntu)
• util-linux >= 2.25.2
• coreutils >= 7.5

Because most distributions do not ship a new enough version of util-linux you will probably need to grab the sources from here and compile it yourself.

Additionally your system will need to be configured with the following:

• A btrfs filesystem mounted under /var/shocker
• A network bridge called bridge0 and an IP of 10.0.0.1/24
• IP forwarding enabled in /proc/sys/net/ipv4/ip_forward
• A firewall routing traffic from bridge0 to a physical interface.

Even if you meet the above prerequisites you probably still want to run shocker in a virtual machine. Shocker runs as root and among other things needs to make changes to your network interfaces, routing table, and firewall rules.

FAQ

Error: btrfs: command not found

This means btrfs is not available on your machine. Luckily many package managers offer a way to install this in a single command:

• Debian/Ubuntu: sudo apt-get install btrfs-tools

Error: x is not a btrfs filesystem

That means we don't have a btrfs filesystem mounted, so let's create one! From a file! Because that's easier than doing partitions!

# create a new filesystem from an empty file 
# skip this step if mounting an actual device 
$ dd if=/dev/zero of=btrfs-hdd.img bs=1G count=2
$ sudo losetup loop0 btrfs-hdd.img
 
# mount the filesystem 
$ sudo mkfs.btrfs /dev/loop0
 
# create `/var/shocker` if it does not exist 
$ [ -d '/var/shocker' ] || sudo mkdir -p '/var/shocker'
 
# open file as block device and mount 
$ sudo mount '/dev/loop0' '/var/shocker'
$ sudo btrfs filesystem show '/var/shocker'

Error: /tmp does not exist

Not every distro adheres to the Linux Filesystem Hierarchy Standard, but no need to sweat about it, we can create our own:

$ sudo mkdir /tmp
$ sudo chmod 1777 /tmp   # open to everyone + set sticky bit 

Error: argument "x" is wrong: Device does not exist

This means that a network device is not found. To enable it run shocker route <devicename> to setup iptables rules and link the device.

Error: libcgroup initialization failed: Cgroup is not mounted

This means cgroups are not yet mounted on your system. Use cgconfig to start them up (example below uses System V init):

$ sudo service cgconfig start

License

GPL-3