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Table of Contents
Docker
Docker, The Linux container engine is an open source project to pack, ship and run any application as a lightweight container.
Have look at Docker getting started.
Prerequisites
kernel with USER_NS
, USER_NET
, etc.
Setup Cgroups
Easiest way is to install libcgroup package and enable all cgroup types:
# install libcgroup and enable mounts poldek -u --noask libcgroup sed -i -e '/^#mount/,$ s/^#//' /etc/cgconfig.conf service cgconfig start
Network Configuration
IPv4 packet forwarding is disabled by default in PLD Linux, so internet access from inside
the container will not work unless net.ipv4.ip_forward
is enabled:
WARNING: IPv4 forwarding is disabled.
To fix, run:
sudo sysctl -w net.ipv4.ip_forward=1
Or, to enable it more permanently, enable it on the host's /etc/sysctl.conf:
net.ipv4.ip_forward=1
Rights
Don't run docker as root
. Add your user to docker
group in host to be able to run from your own user.
Whoever, we still consider that more secure approach than just running as root. Accidental damage to Host system is minimized this way.
How To
Maintenance
Getting rid of stopped containers
docker ps -f status=exited docker ps -q -f status=exited | xargs -r docker rm
Getting rid of unused images
docker images --filter dangling=true docker images --filter dangling=true --quiet | xargs -r docker rmi
Getting rid of unused volumes
docker volume ls -f dangling=true docker volume ls -qf dangling=true | xargs -r docker volume rm
For Docker < 1.9, see docker-cleanup-volumes tool.
PLD Base image
Simple script to create new base image for pld:
- mkimage-pld.sh
#!/bin/sh set -e ROOTFS=~/root IMAGE=pld # to clean up: docker rmi $IMAGE # build rpm -r $ROOTFS --initdb install -d $ROOTFS/dev/pts mknod $ROOTFS/dev/random c 1 8 -m 644 mknod $ROOTFS/dev/urandom c 1 9 -m 644 mknod $ROOTFS/dev/full c 1 7 -m 666 mknod $ROOTFS/dev/null c 1 3 -m 666 mknod $ROOTFS/dev/zero c 1 5 -m 666 mknod $ROOTFS/dev/console c 5 1 -m 660 poldek -r $ROOTFS --up -u bash iproute2 coreutils poldek # cleanups PKGS="cracklib-dicts ca-certificates" for pkg in $PKGS; do rpm -r $ROOTFS -q $pkg && rpm -r $ROOTFS -e $pkg --nodeps done # and import tar -C $ROOTFS -cf- . | docker import - $IMAGE # and test docker run -i -u root $IMAGE /bin/echo Success.
# sh -x /vagrant/mkimage-pld.sh + rpm -r /home/vagrant/root --initdb + poldek -r root --up -u bash iproute2 + docker import - pld # docker run -i -t pld bash WARNING: IPv4 forwarding is disabled. [root@e8d2bb1215c2 /]# id uid=0(root) gid=0(root) groups=0(root)
You can see more available samples in docker/contrib/.
also, you can try glen's pld test image:
vagrant@pld64 ~$ sudo docker run -i -t glen/pld bash root@ae0aac5de155 ~#
Vagrant
To play around inside vagrant, create Vagrantfile
and run vagrant up
followed by vagrant ssh
:
mkdir test cd test # use curl or wget curl -sS > Vagrantfile https://www.pld-linux.org/_export/code/packages/docker?codeblock=4 || \ wget -q -O Vagrantfile https://www.pld-linux.org/_export/code/packages/docker?codeblock=4 vagrant up vagrant ssh
- Vagrantfile
# -*- mode: ruby -*- # vi: set ft=ruby : BOX_NAME = ENV['BOX_NAME'] || "pld64" BOX_URI = ENV['BOX_URI'] || "ftp://ftp.pld-linux.org/people/glen/vm/pld64.box" hostname = File.basename(File.dirname(__FILE__)) print "\033k#{hostname}\033\\" Vagrant::Config.run do |config| # Setup virtual machine box. This VM configuration code is always executed. config.vm.box = BOX_NAME config.vm.box_url = BOX_URI # Provision docker and new kernel if deployment was not done if Dir.glob("#{File.dirname(__FILE__)}/.vagrant/machines/default/*/id").empty? pkg_cmd = "set -xe; " # install libcgroup and enable mounts pkg_cmd << "poldek -u --noask libcgroup; " pkg_cmd << "sed -i -e '/^#mount/,$ s/^#//' /etc/cgconfig.conf; " pkg_cmd << "service cgconfig start; " # ensure ip forward is enabled pkg_cmd << "sed -i -e '/^net.ipv4.ip_forward/ s/0/1/' /etc/sysctl.conf; " pkg_cmd << "sysctl -p; " # Add docker package and start it pkg_cmd << "poldek -u --noask lxc-docker; " pkg_cmd << "service lxc-docker start; " pkg_cmd << "usermod -A docker vagrant; " # Add glibc locales pkg_cmd << "poldek -u glibc-localedb-all; " # Make some more space for containers pkg_cmd << "poldek -u xfsprogs; ldconfig; " pkg_cmd << "lvextend --size=+3G /dev/sys/rootfs; xfs_growfs /; " config.vm.provision :shell, :inline => pkg_cmd end end # Providers were added on Vagrant >= 1.1.0 Vagrant::VERSION >= "1.1.0" and Vagrant.configure("2") do |config| config.vm.provider :virtualbox do |vb| config.vm.box = BOX_NAME config.vm.box_url = BOX_URI # ssh agent forwarding can be useful #config.ssh.forward_agent = true # Make VM accessible outside VM itself, and use eth1 device #config.vm.network :public_network, { bridge: 'eth1', auto_config: true } end end