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Google Cloud blog, gently dissuading you from running a traditional DB in K8s: https://cloud.google.com/blog/products/databases/to-run-or-n...

K8s docs explaining how to run MySQL: https://kubernetes.io/docs/tasks/run-application/run-replica...

You could also run it with Nomad, and skip a few layers of complexity: https://learn.hashicorp.com/nomad/stateful-workloads/host-vo... / https://mysqlrelease.com/2017/12/hashicorp-nomad-and-app-dep...

One of the big problems of K8s is it's a monolith. It's designed for a very specific kind of org to run microservices. Anything else and you're looking at an uphill battle to try to shim something into it.

You can also skip all the automatic scheduling fancyness and just build system images with Packer, and deploy them however you like. If you're on a cloud provider, you can choose how many instances of what kind (manager, read-replica) you deploy, using the storage of your choice, networking of choice, etc. Then later you can add cluster scheduling and other features as needed. This gradual approach to DevOps allows you to get something up and running using best practices, but without immediately incurring the significant maintenance, integration, and performance/availability costs of a full-fledged K8s.






> One of the big problems of K8s is it's a monolith

while I pretty much agree with everything else you mention, I think it's kind of the opposite; since k8s is fundamentally an API, it's very modular and extensible and this is why it's being successful (I agree it wants you to do things its way and things like databases need to be shimmed at the moment, so the conclusion is similar... for now)


It looks like microservices from the high level. But then you dig into each component, and realize that other than using APIs, they still require all the other components, use a shared storage layer, sometimes use non-standard protocols. The kube-controller-manager alone is literally a tiny monolith: a single binary with 5 different controllers in it. K8s operates like a monolith because you mostly can't just remove one layer and have it keep running.

Compare that to HashiCorp's tools. You can run a K8s-like system composed mostly of Hashi's tools, but you can also run each of those tools as a single complete unit of just itself. Now, each of those tools is actually multiple components in one, like mini-monoliths. But in operation, they can work together or as independent services. The practical result is truly stand-alone yet reusable and interoperable components. That's the kind of DevOps methodology I like: buy a wheelbarrow today and hitch it to an ATV next week, rather than going out and buying a combine harvester before you need it.


Yes, these are very good points, all true, thanks.

I still think that while this monolith has its drawbacks, the fact that any component can be substituted as long as it confirms to the official API is really powerful. For example k3s uses sqlite instead of etcd.

Having small components that do one thing well (Unix philosophy) is certainly one way to go (I still haven't found somebody who doesn't love Hashicorp tooling, myself included) but the k8s idea of having one (big, possibly bloated for many cases) "standard" way of doing things while being customizable/extensible is really powerful. If Hashi came up with some (extendible) glue/package tooling then a lot of people doing/looking at k8s right now will seriously look at them (myself included).




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