p8952/bocker: Docker implemented in around 100 lines of bash

Docker implemented in around 100 lines of bash.

The following packages are needed to run bocker.

• btrfs-progs
• curl
• iproute2
• iptables
• libcgroup-tools
• 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/bocker
• 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.

For ease of use a Vagrantfile is included which will build the needed environment.

Even if you meet the above prerequisites you probably still want to run bocker in a virtual machine. Bocker runs as root and among other things needs to make changes to your network interfaces, routing table, and firewall rules. I can make no guarantees that it won’t trash your system.

$ bocker pull centos 7
######################################################################## 100.0%
######################################################################## 100.0%
######################################################################## 100.0%
Created: img_42150

$ bocker images
IMAGE_ID        SOURCE
img_42150       centos:7

$ bocker run img_42150 cat /etc/centos-release
CentOS Linux release 7.1.1503 (Core)

$ bocker ps
CONTAINER_ID       COMMAND
ps_42045           cat /etc/centos-release

$ bocker logs ps_42045
CentOS Linux release 7.1.1503 (Core)

$ bocker rm ps_42045
Removed: ps_42045

$ bocker run img_42150 which wget
which: no wget in (/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/root/bin)

$ bocker run img_42150 yum install -y wget
Installing : wget-1.14-10.el7_0.1.x86_64                                  1/1
Verifying  : wget-1.14-10.el7_0.1.x86_64                                  1/1
Installed  : wget.x86_64 0:1.14-10.el7_0.1
Complete!

$ bocker ps
CONTAINER_ID       COMMAND
ps_42018           yum install -y wget
ps_42182           which wget

$ bocker commit ps_42018 img_42150
Removed: img_42150
Created: img_42150

$ bocker run img_42150 which wget
/usr/bin/wget

$ bocker run img_42150 cat /proc/1/cgroup
...
4:memory:/ps_42152
3:cpuacct,cpu:/ps_42152

$ cat /sys/fs/cgroup/cpu/ps_42152/cpu.shares
512

$ cat /sys/fs/cgroup/memory/ps_42152/memory.limit_in_bytes
512000000

$ BOCKER_CPU_SHARE=1024 \
	BOCKER_MEM_LIMIT=1024 \
	bocker run img_42150 cat /proc/1/cgroup
...
4:memory:/ps_42188
3:cpuacct,cpu:/ps_42188

$ cat /sys/fs/cgroup/cpu/ps_42188/cpu.shares
1024

$ cat /sys/fs/cgroup/memory/ps_42188/memory.limit_in_bytes
1024000000

• docker build †
• docker pull
• docker images
• docker ps
• docker run
• docker exec
• docker logs
• docker commit
• docker rm / docker rmi
• Networking
• Quota Support / CGroups

† bocker init provides a very limited implementation of docker build

• Data Volume Containers
• Data Volumes
• Port Forwarding

Copyright (C) 2015 Peter Wilmott

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program. If not, see http://www.gnu.org/licenses/.