27 Jul 2016 in Kubernetes, scheduler, Elixir

Scheduling Your Kubernetes Pods With Elixir

Kelsey Hightower gave a really interesting talk at ContainerSched about how to create your own scheduler using the Kubernetes HTTP API.

The talk was awesome. It's incredible to see what kind of things you can do with a base system as good as Kubernetes.

However, I missed one thing. The example provided by Kelsey was a Go application. Which is the main language used with Kubernetes. So, if you look at that code without any context, you might think it's using some kind of Kubernetes internal packages. But it's not! It's a standalone piece of code that happens to make some HTTP calls.

To illustrate this point, I decided to write my own scheduler, in a different language. In my case, Elixir, because that's the language I happen to be learning at the moment.

This post isn't an intro to Elixir, but the code should be easy to follow.

Also, I'm going to use localhost when accessing the Kubernetes API. Why? For simplicity. If we run kubectl proxy on a computer connected to the Kubernetes master, we will not need to deal with authorization, hosts, and so on. The proxy command will do it for us.

So, let's dive in.

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25 Jul 2016 in Workflow, Release, Announcement

Deis Workflow 2.2 Release

It may be the hottest July on record but we've got some new cool stuff in the latest release of Deis Workflow. Sit back, grab a cold drink, and check out the latest Workflow release.

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22 Jul 2016 in Docker, storage, file system, drivers, volumes

Docker Storage: An Introduction

There are lots of places inside Docker (both at the engine level and container level) that use or work with storage.

In this post, I'll take a broad look at a few of them, including: image storage, the copy-on-write mechanism, union file systems, storage drivers, and volumes.

You'll need Docker installed locally on your machine if you want to try out some of the commands in this post. Check out the official docs for how to install Docker on Linux, or our previous post showing how to install Docker on a non-Linux machine.

Let's dive in.

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15 Jul 2016 in Docker, Tutorial

Deploying a Simple and Secure Docker Registry

There comes a time in everybody's life where they realize they have to run their own Docker Registry. Unfortunately there's not a lot of good information on how to run one. Docker's documentation is pretty good, but is verbose and spread across a lot of different pages. This means having half a dozen tabs open and searching for the right information.

It's common to run the Docker Registry with little to no security settings, and fronting it with NGINX or Apache to provide this security. But there is another way.

In this post, I will show how to run the Docker Registry securely by itself with both TLS certificate backed encryption and certificate based endpoint authorization.

If you need to do advanced stuff like authenticate against LDAP, you'll still want to go down the reverse proxy road.

For simplicity, I will will assume a single registry running on the local filesystem and will avoid using OS specific init systems by focusing just on the docker commands themselves. This should work on any system capable of running Docker.

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14 Jul 2016 in Docker, Security

Securing Docker With TLS Certificates

By default, Docker has no authentication or authorization for its API, instead relying on the filesystem security of its UNIX socket, /var/run/docker.sock, which by default is only accessible by the root user.

This is fine for the basic use case of only accessing the Docker API on the local machine via the socket as the root user. However if you wish to use the Docker API over TCP, you'll want to secure it so you don't have to give out root access to anyone that happens to poke you on the TCP port.

Docker supports using TLS certificates (both on the server and the client) to provide proof of identity. When set up correctly it will only allow clients and servers with a certificate signed by a specific CA to talk to eachother.

While not providing fine grained access permissions, it does at least allow us to listen on a TCP socket and restrict access with the bonus of also providing encryption.

In this post, I will detail what is required to secure Docker running on a CoreOS server. I will assume you already have a CoreOS server set up and running. If not, check out this previous Deis blog post covering CoreOS and VirtualBox.

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