Perl containers

YAPC::EU 2014 SofiaYAPC::EU 2014 Sofia

Create your containers with PerlCreate your containers with Perl


So first... Who am I?So first... Who am I?


So first... Who am I?So first... Who am I?

➢ System Administrator at heartSystem Administrator at heart➢ Teaching at Sofia UniversityTeaching at Sofia University➢ Organizing events like this one...Organizing events like this one...➢ CEO of 1H Ltd.CEO of 1H Ltd.➢ CTO of GetClouderCTO of GetClouder➢ Chief architect of Siteground.comChief architect of Siteground.com


The current state of containers

➢ LXC➢ Docker➢ lmctfy➢ A bunch of other small implementations➢ Build it your self


Root inside the containerRoot inside the container

ONLY WITH LXCONLY WITH LXC


So why would you need a Perl implementation

➢ Patching LXC is writing in C...➢ Writing in C is not very user friendly➢ If most of your logic is already in Perl...➢ Keep less moving blocks in your architecture


So what the hell is a container?

➢ chroot ( isolate the directory tree )➢ unshare ( create new namespace(s) )➢ cgroups ( add limits )➢ drop capabilities (optional)


What do we have in Perl?

➢ Linux::Unshare➢ Linux::Setns


What do we need?

➢ Linux::Capabilities➢ Linux::Networking


What am I proposing?a toolkit

➢ pc-start➢ pc-stop➢ pc-restart➢ pc-list➢ pc-top➢ pc-attach


➢ pre-read-config hook➢ read yaml config➢ post-read-config➢ prepare cgroup➢ post-cgroup-setup hook➢ fork

➢ prepare mount hook➢ chroot➢ post-chroot hook➢ unshare➢ post-unshare hook➢ drop caps➢ post-dropcaps hook➢ setup networking➢ post-networking hook➢ fork -> exec init➢ post init hook

➢ setup user mappings ➢ post usermap hook

So let's So let's look inside the look inside the implementation implementation

in depthin depth

pc-startpc-start


➢ pre-read-config hook➢ read yaml config➢ post-read-config➢ check if there is a cgroup➢ check if the cgroup is not empty➢ check if the base device➢ find a FD from one of the PIDs➢ pre-attach hook➢ setns

➢ execute bash -i

pc-attachpc-attach


➢ pre-read-config hook➢ read yaml config➢ post-read-config➢ check if there is a cgroup➢ check if the cgroup is empty➢ do pc-attach

➢ execute halt

pc-stoppc-stop


➢ loop trough the configs➢ check if the cgroup exists➢ check if the cgroup is empty➢ check if it has init running inside

pc-listpc-list


➢ Loop trough all the configs➢ check if the cgroup exists➢ check if the cgroup is not empty➢ collect the following stats➢ cpu usage➢ memory usage➢ I/O usage➢ Network usage

➢ It should allow the admin to➢ sort each by each resource ➢ handle signals➢ configure the interface

pc-toppc-top


http://github.com/hackman/azilian

http://github.com/hackman/azilian

Engineering

Perl containers