http://www.developer.com/design/containers-101.html

So attended a local tech meetup.com presentation on Containers last night, more specifically geared towards Docker.

To me, it seems that it was trying to take VMs into another level with the ability to write code once and have it run everywhere in a type of sandbox environment and should speed up the SDLC.

I've noticed that Red Hat is pushing out some of their errata via Container Images, so that is why I'm taking an interest.

Was wondering what others think or what their experience has been with Containers?

thanks

The idea behind containers is that they're more efficient than full VMs because only the pieces you need are in each container and you can have multiple containers for each environment.

Here we started using containers for a project about a year ago. The host OS is CoreOS but the containers under that can be and are a mix so we have CentOS, Ubuntu, Fedora and other containers. We are using Docker as well.

RedHat's Atomic is a container platform that has been making major changes in the last year (I suspect in reaction to the popularity of other platforms) so they now use Docker. Their main selling point in presentations I've been to is that they provide the repository of containers and vet them unlike the free for all you get with things such as CoreOS' repositories of containers. Anyone can add to the latter so if you're not doing due dilligence the chance you're bringing in something nasty is fairly high.

Developers love containers because they don't have to ask admins to install the latest version of whatever they want to use. That is to say they can have a container with one version of php another with a different version of php, or 3 with different versions of perl, or a couple with different versions of Java etc... and mix and match for the environment they're setting up.

I haven't personally used containers, but a Docker container is essentially a chroot with a version-controlled filesystem, distributable as a single file.

The utility of that should be obvious.

It's more than just a chroot-jail.

I like to think of it that "containers use VM technology to implement some of the environment that the container-occupant sees, but not (as in a true VM ...) all of it. The host-OS provides some services to all containers. But the technology in the CPU that provides for hypervisors provides a far-greater degree of isolation for the container.

If you are running server farms, carrying-around "an entire virtual operating system with all the trimmings" (hundreds or thousands of times ...) might well be a lot of overkill. You just don't need (maybe ...) that level of duplication and total-isolation. And, you might encounter impediments if the various things that you're hosting need to coordinate with one another (albeit in a strictly-controlled way). "Containers" deploy the virtualization capabilities of the underlying hardware in a different way. They still "isolate the environment with an iron fist," but the level of isolation does not have to be total. Although the client, running in the container, is walled-off completely (much more completely than "chroot" can do ...), the container itself is not.

I think containers are great in a networked/cloud type of environment where the enhanced security they provide has practical application.

I so far, at least, see no benefit from the kewl new package managers like snappy and flapjack or flippy-floppy or whatever it's called for the home user, other than to create a mishmosh of mediocrity with an appeal to the indolent.

But that's just me.

I saw the title of this thread and thought "Tupperware?!"

I'm obviously out-of-touch

Now you've done it! I predict within a year someone will come out with a container distro called tooperware (to avoid TM issues).

"Silly rabbit." Tupperware containers are used to hide geocaches in the woods! (I seem to recall someone saying that they were also good for storing food, too.)