Kubernetes – Software / Wetware

Crashed blog… now restored(1 min read)

So, I pushed the single-server Kubernetes cluster that I was running my blog on a little too far, and it crashed into a bit of a heap. The pods running the different sites, including this blog, failed, and the underlying database got corrupted.

It has been down for a few weeks now. Initially I thought it was just a server issue and rebooted. When it didn't come up, I did little bits of investigation over the following weeks, just a few hours at a time, to figure out the issue.

I managed to work out how to restore the database and get it working, but the server was not stable. It would quickly crash, and trying to activate more than one site would just cause problems.

Kubernetes is quite complicated, and there is a lot of overhead for a single server. It was still a good exercise to understand the complexities of deploying Kubernetes on IPv6.

Now, deploying multiple services via containers is still a good approach, with Kubernetes simply a way to orchestrate, and manage, a large number of containers. So, I can pretty much just run the same containers, just directly (instead of inside Kubernetes).

As you can see, from this blog entry, my services are now back up and running.

There was still the complexity of running on IPv6 only, which I should probably write up in more detail, but for now a lot of it was based on an article by Stefan Kleeschulte, https://medium.com/@skleeschulte/how-to-enable-ipv6-for-docker-containers-on-ubuntu-18-04-c68394a219a2

Apps on Kubernetes IPv6 – Kubeapps, WordPress(8 min read)

Once you have Kubernetes running on IPv6 only the next step is to install some apps.

This is my first post written on my new WordPress instance, hosted on Kubernetes IPv6 only. If you are reading it, then it is working 🙂

Of course apps have their own issues not being configured by default to work with IPv6, so for each app you need to test and work out what configuration details need to be tweaked (assuming the app supports IPv6 in the first place).

To start off with, I installed Kubeapps, to get an application management dashboard, and then used that to install WordPress.

With WordPress installed, I exported the content from my old blog and then imported it into the new instance, and tweaked a few WordPress settings.

The final step was to configure the Mythic Beasts reverse proxy, to make my blog available for legacy IPv4 users.

Kubernetes on IPv6 only(9 min read)

Kubernetes is an open source platform for managing containerised applications.

IPv6 is the next generation Internet protocol, and running on IPv6 only simplifies configuration and administration, and avoids the performance issues and complexities of IPv4 encapsulation, NAT, and conflicting private address ranges.

The default configuration of Kubernetes is IPv4, and there are few, and scattered, examples and guidance for setting up IPv6 dual stack, let alone single stack.

I have collected instructions from the different sources into a single guide to successfully deploy Kubernetes with IPv6 only.

See the guide for full instructions:

https://github.com/sgryphon/kubernetes-ipv6

The blog post contains some additional background on what I did to gett the deployment working. The deployment was tested on Ubuntu 20.04 running on an IPv6 only virtual server from Mythic Beasts.

Surviving with IPv6 only(4 min read)

Trying to use an IPv6 only machine runs into a roadblock when you need to access a legacy IPv4 resource.

The best solution would be to convince services to move to an IPv6 first solution, incrementally adding reverse proxies for existing services and deploying new services to IPv6 only, with an IPv4 gateway only as needed.

Deploying new services to IPv6 only is much simpler than dual-stack, as you only need to worry about one set of configuration, firewalls, etc. Adding an IPv4 proxy on top, for legacy support, is then a simple, and contained, extension.

However, until that happens you still need a solution.

I found setting up DNS64 + NAT64 for my IPv6 only machines was pretty simple with my OpenWRT router.