Docker design concept

	Work in Progress:
	This page is a Work in Progress. The contents off this page may be in flux, please have a look at this page history the to see list of changes.

	Note:
	Various configuration entries may be deprecated

Purpose

This page holds a conceptual design for Docker on SME Server. See more details on Docker here

Overview

Design principles

• This design concept only addresses demonized containers and not interactive containers.
• This design only addresses containers that hold application(s) for end users. Not for sys admins.
• Transparent 'Click to run' user experience
• No integration with Server Manager (Yet).
• Full integration in SME Sever templating system and SME Server db databases
• Pre-build images are not available yet
• No build-in pre-checks regarding starting a container and server capacity
• The design is intended for a single SME Server host, not a cluster or a farm.
• May not effect or compromise default SME Server functionality, stability and security

Resources

Possible resources and tools that can be used:

Eixo::Docker perl library

a CPAN perl library for managing images and containers

http://search.cpan.org/~alambike/Eixo-Docker-1.103/lib/Eixo/Docker.pod

https://github.com/alambike/eixo-docker

The Eixo library interacts with Docker API via a TCP socket. By default Docker starts without a TCP socket attached, so we have to add it to the Docker service arguments in /etc/sysconfig/docker. The default port via which the Docker API communicates is 4243 but it can be any port. Below is an example /etc/sysconfig/docker file:

# /etc/sysconfig/docker
#
# Other arguments to pass to the docker daemon process
# These will be parsed by the sysv initscript and appended
# to the arguments list passed to docker -d

other_args="-g /home/e-smith/files/docker -H 127.0.0.1:4243 -d"

Options

This document does not address any integration with Server Manager. All input is to be considered a flat file or manual db entries.

A. Container Options

Start

The docker client can be invoked with various flags and arguments. These flags and arguments are past to the docker daemon to construct the docker container and run it. To see all docker client command execute:

docker

To see all available arguments, execute

docker -h

B. Docker options

• TBA
• Docker cluster?? (Multiple SME Servers load balancing docker containers)

C. Image options

• Linked containers

To inspect an image and with what (networking) options it was constructed, one can inspect the image by:

docker inspect [imagename]

SME Databases

Container options

Container options can be passed to the container at 'boot' time. These options can include the following aspects:

• network (ports, port mapping)
• 'cpu' (load)
• memory allocated (size)
• Storage (mount paths, both inside container and (remote) host)
• Domain names (FQDN (sub)domains, Web server Aliases)
• Links to other containers (container wordpress automatically starts container MySQL)

Unlike containers, images themselves do not carry this information, but only the exposed (open) ports.

Hence the usage of SME Server db system to store preferred options per container.

Syntax:

db docker_containers [name]

Key:

docker_containers [name]=service

Types:

status	enabled / disabled
TCPPort	n , n
UDPPort	n , n
PortMapping	native / custom
PortMappingPorts	n:n , n:n
access	private / public
network	bridge / host
MountPath	path , path
Interlinked	[alias]
InterLinkPriority	n
MaxMemory	n
SubDomain	enabled / disabled
SubDomainName	name
WebAlias	name
DataMount	container / host
DataMountWrite	yes / no
DataMountPath	path

Image options

Syntax:

db docker_images

Key:

docker_images [name]=service

SME Template/fragments

• TBA

Start/Stop events

• Manual on console
• Time based by cron
• Triggered by an event

Create a SME docker Base image

WIP --Stephdl (talk) 15:56, 15 September 2014 (MDT)

Install docker to your sme, be aware that you have to do it on a SME9 64 bit original script : https://github.com/docker/docker/blob/master/contrib/mkimage-yum.sh

Create your repository file and save it to /root/repo_file

#------------------------------------------------------------
#	       !!DO NOT MODIFY THIS FILE!!
# 
# Manual changes will be lost when this file is regenerated.
#
# Please read the developer's guide, which is available
# at http://www.contribs.org/development/
#
# Copyright (C) 1999-2006 Mitel Networks Corporation
#------------------------------------------------------------

[base]
enabled=1
mirrorlist=http://mirrorlist.centos.org/?release=6&arch=x86_64&repo=os
name=CentOS - os
gpgcheck=0
enablegroups=1
exclude=initscripts libgsf

[centosplus]
enabled=0
mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=centosplus
name=CentOS - centosplus
gpgcheck=0
enablegroups=0

[contrib]
enabled=0
mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=contrib
name=CentOS - contrib
gpgcheck=0
enablegroups=0 

[extras]
enabled=0
mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=extras
name=CentOS - extras
gpgcheck=0
enablegroups=0 

[fasttrack]
enabled=0
mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=fasttrack
name=CentOS - fasttrack
gpgcheck=0
enablegroups=0

[smeaddons]
enabled=1
mirrorlist=http://mirrorlist.contribs.org/mirrorlist/smeaddons-9
name=SME Server - addons
gpgcheck=0
enablegroups=1 

[smecontribs]
enabled=0
mirrorlist=http://mirrorlist.contribs.org/mirrorlist/smecontribs-9
name=SME Server - contribs
gpgcheck=0
enablegroups=1 

[smedev]
enabled=0
mirrorlist=http://mirrorlist.contribs.org/mirrorlist/smedev-9
name=SME Server - dev
gpgcheck=0
enablegroups=1 

[smeextras]
enabled=1
mirrorlist=http://mirrorlist.contribs.org/mirrorlist/smeextras-9
name=SME Server - extras
gpgcheck=0
enablegroups=1

[smeos]
enabled=1
mirrorlist=http://mirrorlist.contribs.org/mirrorlist/smeos-9
name=SME Server - os
gpgcheck=0
enablegroups=1 

[smetest]
enabled=0
mirrorlist=http://mirrorlist.contribs.org/mirrorlist/smetest-9
name=SME Server - test
gpgcheck=0
enablegroups=1 

[smeupdates]
enabled=1
mirrorlist=http://mirrorlist.contribs.org/mirrorlist/smeupdates-9
name=SME Server - updates
gpgcheck=0
enablegroups=1 

[smeupdates-testing]
enabled=0
mirrorlist=http://mirrorlist.contribs.org/mirrorlist/smeupdates-testing-9
name=SME Server - updates testing
gpgcheck=0
enablegroups=1

[updates]
enabled=1
mirrorlist=http://mirrorlist.centos.org/?release=6&arch=x86_64&repo=updates
name=CentOS - updates
gpgcheck=0
enablegroups=1
exclude=initscripts libgsf 

• first create a file and record the content

vim /root/docker_images

#!/usr/bin/env bash
#
# Create a base CentOS Docker image.
#
# This script is useful on systems with yum installed (e.g., building
# a CentOS image on CentOS). See contrib/mkimage-rinse.sh for a way
# to build CentOS images on other systems.
usage() {
cat <<EOOPTS
$(basename $0) [OPTIONS] <name>
OPTIONS:
-y <yumconf> The path to the yum config to install packages from. The
default is /etc/yum.conf.
EOOPTS
exit 1
}
# option defaults
yum_config=/etc/yum.conf
while getopts ":y:h" opt; do
case $opt in
y)
yum_config=$OPTARG
;;
h)
usage
;;
\?)
echo "Invalid option: -$OPTARG"
usage
;;
esac
done
shift $((OPTIND - 1))
name=$1
if -z $name ; then
usage
fi
#--------------------
target=$(mktemp -d --tmpdir $(basename $0).XXXXXX)
set -x
mkdir -m 755 "$target"/dev
mknod -m 600 "$target"/dev/console c 5 1
mknod -m 600 "$target"/dev/initctl p
mknod -m 666 "$target"/dev/full c 1 7
mknod -m 666 "$target"/dev/null c 1 3
mknod -m 666 "$target"/dev/ptmx c 5 2
mknod -m 666 "$target"/dev/random c 1 8
mknod -m 666 "$target"/dev/tty c 5 0
mknod -m 666 "$target"/dev/tty0 c 4 0
mknod -m 666 "$target"/dev/urandom c 1 9
mknod -m 666 "$target"/dev/zero c 1 5
#yum -c "$yum_config" --installroot="$target" --setopt=tsflags=nodocs \
#--setopt=group_package_types=mandatory -y groupinstall Core

###here it is for testing purpose, you will build a pure centos base docker image (keep only one yum line of course)
#yum -c "/root/repo_file" --installroot="$target" --setopt=tsflags=nodocs --setopt=group_package_types=mandatory -y groupinstall Core ###this line is to test and build a pure centos base in order to test
###with the line below we take all from smeos, not really uptodate
#yum -c "/root/repo_file" --installroot="$target" --setopt=tsflags=nodocs --setopt=group_package_types=mandatory -y install --disablerepo=* --enablerepo=smeos,smeextras e-smith\* smeserver\*
###here we take rpm in the most uptodate version
yum -c "/root/repo_file" --installroot="$target" --setopt=tsflags=nodocs --setopt=group_package_types=mandatory -y install e-smith\* smeserver\*

###a bit of clean
yum -c "/root/repo_file" --installroot="$target" -y clean all



cat > "$target"/etc/sysconfig/network <<EOF
NETWORKING=yes
HOSTNAME=localhost.localdomain
EOF

# effectively: febootstrap-minimize --keep-zoneinfo --keep-rpmdb
# --keep-services "$target". Stolen from mkimage-rinse.sh
# locales
rm -rf "$target"/usr/{{lib,share}/locale,{lib,lib64}/gconv,bin/localedef,sbin/build-locale-archive}
# docs
rm -rf "$target"/usr/share/{man,doc,info,gnome/help}
# cracklib
rm -rf "$target"/usr/share/cracklib
# i18n
rm -rf "$target"/usr/share/i18n
# sln
rm -rf "$target"/sbin/sln
# ldconfig
rm -rf "$target"/etc/ld.so.cache
rm -rf "$target"/var/cache/ldconfig/*

#version=

if [ -r "$target"/etc/redhat-release ]; then
version="$(sed 's/^[^0-9\]*\([0-9.]\+\).*$/\1/' "$target"/etc/redhat-release)"
fi

if [ -z "$version" ]; then
echo >&2 "warning: cannot autodetect OS version, using '$name' as tag"
version=$name
fi

tar --numeric-owner -c -C "$target" . | docker import - $name:$version
docker run -i -t $name:$version echo success
rm -rf "$target"

give the permissions to the file

chmod u+x /root/docker_images

and launch the script

/root/docker_images [name_of_your_image]

you have to wait, the download depends of your bandwith, once done you could see 'success'

docker run -i -t sme9_real:6.5 echo success
success

to launch your image

docker run -i -t  sme9_real:6.5 bash

see

docker images

after that you have an image but we need to reconfigure it