> Fundamentally, the argument seems to come down to "you don't have a record of what you once asked the API server to do", and that's fair enough - you don't. But that has nothing to do with imperative or declarative models.

You do actually have this record. First of all, because k8s has an audit log, and secondly because deployments maintain a revision history (so you can always rollback--kubectl even supports this via `kubectl rollback undo`).

You're correct, but, when approaching this from the human perspective, it's less about the technology and the reality and more about "do I have a record of the last state I asked the cluster to be in before I fucked it up?". Ultimately that's what matters. Auditability is great, but in practice, when the shit hits the fan, can I get the application that brings in our company's money, and our customers rely on to breath, back to the state it was after 5 years and 73 updates?

Updating the manifests, pushing them to version control and having CD deploy them encourages humans to "do the right thing".

It would be quite easy though to just tweak that one environment variable though while I patch in the new image version to update that one service; until the entire cluster dies and I can't retrieve the last definition and need an equivalent cluster up within the hour.

This is really more about the practice of writing down the state you want the cluster to be in (the spec) and showing it to the cluster, than just ordering it to do one thing without context.

In this sense, Declarative Vs Imperative is just a proxy term for "do I have a record of the state I asked the cluster to keep?"

Given that Kubernetes' docs[0] discuss using imperative commands, I think it's a fairly reasonable way to describe it.

[0] https://kubernetes.io/docs/tasks/manage-kubernetes-objects/i...

Why is applying a full manifest “declarative” but applying a patch is “imperative”? That’s clearly an error.

Applying a full manifest is "this is your state now".

Applying a patch is "make these changes to your existing state".

That dependency on existing state is a difference, and it seems to map reasonably well to what declarative/imperative seem to usually be used to mean in this context.

1. A strategic merge patch says "this is your state now" (the only difference is the scope of the state in question, with a full manifest including a bunch of extraneous stuff)

2. "make these changes to your existing state" is still declarative

> Applying a full manifest is "this is your state now".

It isn’t though. It’s “please make the state look like this eventually”. You do not patch state, just spec. Controllers effect the changes.

You're both correct, but you're talking about different states. The parent's "state" is the state of the etcd database and your state is the actual state of the resources that the controllers are managing.

That said, the parent is wrong that a full manifest is declaring the (etcd) state in a way that a (strategic merge) patch isn't--both are declaring etcd state, but a strategic merge patch is doing so in finer-grained increments. A strategic merge patch can declare zero state or many full manifests, while applying full manifests can only work in increments of complete resource manifests. But both are telling Kubernetes "this is your (etcd) state now".

Then open a PR.

This is a strange way to concede an argument, but I’ll take it.