I guess I can just print this out and show to people any time somebody wants to move to k8s.
Most of the diamonds listed here aren’t things you have to remember, they’re statuses that are explicitly called out in the responses of those commands. This is an over-complicated chart that in reality is summed up as: look at the pod, look at the service, look at ingress.
That's one of the strengths with K8s, at least there is documentation, unlike a 1000 line perl script with no tests which does service discovery.
I fully agree on that being a major strength of k8s. Looking at the resource manifests gives a ton of insight into how a system is supposed to function.
Sure but I am not comparing it against manually done / bash script powered / Ansible deployments. Even if I was the CI/CD pipeline would capture many of the problems early and than I have an immutable AMI with autoscaling groups that is very easy to debug, networking setup is super simple and load-balancing is also straightforward to troubleshoot. Cramming all of these into a simple project that is not as easy to debug is not worth the effort for us.
I went through your problem before on a practice cluster and ended up giving up on that one.
Realistically the hard way doesn't actually explain much of the commands you're running, and much of it covers the tedium of getting the many many certs you need to bootstrap everything (which will then expire and not rotate automatically). It's much better to just use kubeadm, and take some time to read all the args to kubelet, kubeadm, kubeproxy, etc...
A complete flow chart of all the possible states for any non-trivial thing appears complex. In practice the actual problems you run into are part of a much smaller set of possibilities.
- using ping
- sshing into a box
- using ssh port forwarding
- using ps aux
- understanding system load
- understanding oom killer messages
- is this systemd? use systemctl, otherwise figure it out
- is this systemd? use journalctl, otherwise figure out where an app is logging
- is nginx running? what box is it running on?
- is the nginx config okay?
- what about haproxy? are health checks going through?
Plus dealing with whatever configuration management system you're using, credential store you're using, etc.
Kubernetes, while complex, does take over a huge chunk of responsibilities from existing deployments. As such, a large part of any debugging will be done via kubectl and on a much different level of abstraction than if you were dealing with individual machines and services deployed on them via Ansible.
Yes, there's new things to learn. But for many cases (not even just scale!) it's quite worth it.
For those that do need a solution like Kubernetes, charts like this are helpful, and the knowledge requirements certainly aren't too steep relative to comparable platforms.
What about Kubernetes makes it especially worth going in and commenting that you don't have a use case for it, in a thread dedicated to Kubernetes? Would you make similar comments about other platforms/libraries/technologies that you, for whatever reason, don't have a use case for?