The Man Who Would Build a Computer the Size of the Entire Internet

Re:The Man Who Would Build a Computer the Size of the Entire... by dxhdr on Monday September 09, 2013 @02:06PM (#6355088)

Can someone explain, briefly, how Docker works? It seems to be getting an increasing amount of buzz lately and I'd like to understand what's going on. All I hear is how you can wrap software in a container that will run anywhere -- not a very helpful explanation. Docker's own website is surprisingly light on specifics... all I know after reading it is that it will, indeed, run almost anywhere! (but how?)

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Re:The Man Who Would Build a Computer the Size of the Entire... by woah on Monday September 09, 2013 @02:13PM (#6355134)

https://www.docker.io/gettingstarted/#

Try the tutorial, if it still doesn't make much sense to you, then it's probably not something you need to worry about.

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Re:The Man Who Would Build a Computer the Size of the Entire... by peterwwillis on Monday September 09, 2013 @02:57PM (#6355418)

Docker is a couple different things in one, so in that respect, it works in different ways.

The main thing Docker does is run arbitrary commands with (or like) LXC, which is basically a way of running a program inside a chroot environment, plus providing a more low-level separation for various parts of the kernel. The end result is your host is kept insulated from the program being run. Here's a great HOWTO on setting up LXC: http://lxc.teegra.net/ And here's a great StackOverflow answer on what Docker/LXC does: http://stackoverflow.com/questions/16047306/how-is-docker-io...

This page from Docker's blog discusses not only the security aspects of a container, but a comparison to traditional virtual machines: http://blog.docker.io/2013/08/containers-docker-how-secure-a...

And the best technical summary from Docker's documentation on what a container is:

"Once you start a process in Docker from an Image, Docker fetches the image and its Parent Image, and repeats the process until it reaches the Base Image. Then the Union File System adds a read-write layer on top. That read-write layer, plus the information about its Parent Image and some additional information like its unique id, networking configuration, and resource limits is called a container."

On top of that it adds a Registry, an Index, and a Remote API. So really, it has remote deployment features, it builds chroot environments, and it combines them and runs applications in a container. Oh, and here is the FAQ: http://docs.docker.io/en/latest/faq/ Summary of their points de-marketingized:

  Portable deployment across machines

You can copy a big image of your chroot environment, application, etc to a remote machine and run it. Docker makes the configuration configurable.

  Application-centric

They added features to make it easier to deploy a program and run it how you want it to run.

  Automatic build

Instead of using a shell script to build your container's chroot environment, you use a Dockerfile, which is like a less useful shell script.

  Versioning

Docker assigns a SHA hash to each image you deploy so you can roll back and do other things on the hash instead of the file name. It also transfers deltas of changes, apparently.

  Component re-use

Due to using a unionfs, you can mount multiple images on top of one another, so you can have smaller separate images and pick the ones you want to use for your app.

  Sharing

You can upload your images to a public repository or download them for your own use.

  Tool ecosystem

Docker has an API. (Actually three APIs)

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