creare docker da zero con golang - giulio de donato

FATTI UN CONTAINERTUTTO TUO!!

@liuggio Giulio De Donato

(con golang e bashism)

What is a Container?


“I once heard that hypervisors are the living proof of operating system's incompetence”

-- Glauber Costa's - LinuxCon Europe 2012


... containers ...“I would love to say months, but let's get realistic”

-- Glauber Costa's - LinuxCon Europe 2012


Is all about ISOLATION


chroot?


Attacks

while true; do mkdir x; cd x; done

bomb() { bomb | bomb & }; bomb


GOAL OF TODAY:

http://9gag.com/gag/aGxbmGz

namespace cgroups ufs


LXC vs DOCKER@liuggio Giulio De Donato

Let’s start with the first set of slides

Once upon a time ...


Spot the diff:


NAMESPACELinux 2.6.23 (released in late 2007)

6 namespaces- mnt (mount points, filesystems)- pid (processes tree)- net (network stack)- ipc (System V IPC)- uts (hostname)- user (UIDs)

Namespaces started in about 2002.


Namespaces processes API consists of these 3 system calls:

● clone() - creates a new process and a new namespace; the newly created process is attached to the new namespace

● unshare()–gets only a single parameter, flags. Does not create a new process; creates a new namespace and attaches the calling processto it.

● setns()- a new system call, for attaching the calling process to an existing namespace;


DEMO Namespace

https://gist.github.com/liuggio/114f506fbe040ac93687dc797b923cbf

1






CGroups!The cgroup (control groups) subsystem is a Resource Management and Resource Accounting/Tracking solution, providing a generic process - grouping framework

It handles resources such as memory, cpu, network, and more; mostly needed in both ends of the spectrum (servers and embedded).∎ Development was started by engineers at Google in 2006 under the name "process containers”∎ Merged into kernel 2.6.24 (2008).∎ cgroup core has 3 maintainers, and each cgroup controller has its own maintainer (cpu memory io)


DEMO CGROUPS

https://asciinema.org/a/7w13btk2uethz2e57lgpfz5ymor https://goo.gl/NyPMFJ

3


https://asciinema.org/a/7w13btk2uethz2e57lgpfz5ym

https://asciinema.org/a/7w13btk2uethz2e57lgpfz5ym

https://goo.gl/NyPMFJ

THIS IS A TREE


WHAT IS IT?


DEMO UFS

apt-get install aufs-tools

https://asciinema.org/~liuggio https://asciinema.org/a/41778

2


https://asciinema.org/~liuggio

https://asciinema.org/~liuggio

https://asciinema.org/a/41778

https://asciinema.org/a/41778

Union File System

PRO

- File level- No caches

CONS

- Bad performance for big files- Not in kernel- Too much layers costs

● merge into a single directory 2 devices

● Combining a large, read-only file system with small write area (like livecd)


ZFS is a combination of a volume manager (like LVM) and a filesystem (like ext4, xfs, or btrfs).ZFS one of the most beloved features of Solaris, universally coveted by every Linux sysadmin with a Solaris background.

● snapshots● copy-on-write cloning● continuous integrity checking against data corruption● automatic repair● efficient data compression

2016


UFS

CGROUPS

namespace


THANKS!@liuggio Giulio De Donato

∎ www.welcometothebundle.com/isolate-a-process-with-no-container-like-docker∎ https://github.com/opencontainers/runtime-spec/blob/master/config-linux.md#namespaces ∎ https://www.opencontainers.org/news/faqs/who-will-be-initial-technical-leadership ∎ http://www.cyberciti.biz/faq/unix-linux-chroot-command-examples-usage-syntax/∎ http://s0.cyberciti.org/uploads/faq/2013/01/bash-chroot-ls-demo.gif∎ https://www.flockport.com/lxc-vs-docker/∎ http://ramirose.wix.com/ramirosen∎ https://lwn.net/Articles/532593/∎ https://lwn.net/Articles/531114/∎ https://lwn.net/Articles/531381/∎ https://lwn.net/Articles/528078/∎ https://docs.docker.com/engine/reference/run/∎ http://www.netdevconf.org/1.1/proceedings/slides/rosen-namespaces-cgroups-lxc.pdf∎ https://www.stgraber.org/2013/12/20/lxc-1-0-blog-post-series/∎ https://skillsmatter.com/skillscasts/7101-building-containers-from-scratch-for-fun-and-profit∎ https://docs.oracle.com/cd/E18752_01/html/817-5093/bkupsnapshot-9.html

∎ https://www.flickr.com/photos/15514374@N05/10164384915/in/photolist-guc8vM-eUsLmk-bUx1od-snDG6D-4EdN6w-dRNW5S-92a5Rc-bqLMQX-9W8h5y-b4nUUZ-qBTHgX-qP1gRX-bjCEPC-9tmmnk-eiz69R-dUwHXM-ff6xuP-J1cvu-7FC9CK-5QNat5-sniS97-dmWZqi-9FJL3F-e5QKNc-oaepa3-dHcamQ-4EJPTP-eB42Pm-aywhxM-eSZ6Gv-jhYq8x-cXnWtd-6HXxUg-8ZKp87-5BL32d-7g3EHP-4gc756-cBECqo-oBFK5Y-9fUMLY-e7z58s-oViSZU-pKrEsE-6J2D5b-6HXwrz-6HXxt8-9k3DeV-9k6CLy-qFGW5B-hrxHnf

∎ https://docs.docker.com/engine/userguide/storagedriver/device-mapper-driver/∎ https://docs.docker.com/engine/userguide/storagedriver/zfs-driver/∎ Presentation template by SlidesCarnival

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creare docker da zero con golang - giulio de donato

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