Docker 1.0 Released 88
Graculus writes: "Docker, the company that sponsors the Docker.org open source project, is gaining allies in making its commercially supported Linux container format a de facto standard. Linux containers are a way of packaging up applications and related software for movement over the network or Internet. Once at their destination, they launch in a standard way and enable multiple containers to run under a single host operating system. 15 months and 8,741 commits after the earliest version was made public, Docker 1.0 has been released."
Re: What is this? (Score:2, Informative)
All the real nerds know about it.
Re:What is this? (Score:5, Informative)
What is Docker?
Docker is an open platform for developers and sysadmins to build, ship, and run distributed applications.
How is this different from Virtual Machines?
Virtual Machines
Each virtualized application includes not only the application - which may be only 10s of MB - and the necessary binaries and libraries, but also an entire guest operating system - which may weigh 10s of GB.
Docker
The Docker Engine container comprises just the application and its dependencies. It runs as an isolated process in userspace on the host operating system, sharing the kernel with other containers. Thus, it enjoys the resource isolation and allocation benefits of VMs but is much more portable and efficient.
https://www.docker.com/whatisdocker/ [docker.com]
What is docker? Docker is... (Score:4, Informative)
Docker is a lot of things, all rolled up into one so it is difficult to describe without leaving out some detail. What is important to one devops person might be unimportant to another. I have been testing docker for the past few months and there are a couple of things about it that I like quite a bit.
I have to explain a couple of things that I like about it before I get to the one that I really like.
1) It has a repository of very bare bones images for ubuntu, redhat, busybox. Super bare bones, because docker only runs the bare minimum to start with and you build from that.
2) You pull down what you want to work with, and then you figuratively jump into that running image and you can set up that container with what you want it to do.
3) (this is what I really like) That working copy becomes a "diff" of the original base image. You can then save out that working image back to the repository. You can then jump on another machine, and pull down that "diff" image (but you don't even really have to think of it as a "diff", you can just think of it as your new container. docker handles all the magic of it behind the scenes. So if you are familiar with git, it provides a git like interface to managing your server images.
It does a lot more than what I describe above, but it is one of the things I was most impressed with.
Re:What is this? (Score:5, Informative)
The point is that don't create a VM. Containers runs applications in their own isolated (as in filesystem, memory, processes, network, users, etc) environment, but just one kernel, no hard reservation of memory or disk, it consumes resources pretty much like native apps.Another difference is at it just need the linux kernel, it runs where a linux kernel (modern enough, 2.6.38+) run, including inside VMs, so you can run them on amazon, google app engine, linode and a lot more.
What docker adds over LXC (Linux Containers) is using a copy-on-write filesystem (so if i get the filesystem for i.e. ubuntu for an app, and another application also tries to use the filesystem of ubuntu, the extra disk use is just what both changed, also cached disk works for both), using cgroups to be able to limit what resources the container can use, and a whole management system for deploying, managing, sharing, packaging and constructing. It enables you to i.e. build a container for some service (with all the servers it need to run, with the filesystem of the distribution you need, exposing just the ports you want to give services on), pack it, and use it as a single unit, deploying it in the amount of servers you want without worrying about conflicting libraries, required packages, or having the right distribution.
If you think that is something academical, Google heavily use containers in their cloud, creating 2 billon containers per week. They have their own container technology (LMCTFY, Let Me Contain That For You) but has been adopting lately Docker, and contributing not just code but also a lot of tools to manage containers in a cloud.
Re:Sound like BSD jails (Score:5, Informative)
It's the same thing as BSD Jails, however there is one big difference with Docker. A container/jail can be shipped to another system running a completely different kernel. This means you can create an Ubuntu 10.04 container and run it on an Ubuntu 14.04 host or RHEL 7 host.
With BSD Jails, you can only ship your jails to the same system unless you spend enough time fiddling around so you can basically do the same thing. Luckily the Docker team is already adding BSD Jails support.