feat: Warn when stack/demo is larger than cluster

[sbernauer]

Description

Related to stackabletech/stackablectl#268

➜  stackable-cockpit git:(feat/check-demo-resoures) ✗ cargo r -p stackablectl -- demo in data-lakehouse-iceberg-trino-spark
    Finished dev [unoptimized + debuginfo] target(s) in 0.10s
     Running `target/debug/stackablectl demo in data-lakehouse-iceberg-trino-spark`
   WARN  The stack has the resource requirements [CPU: 71, Memory: 160Gi, PVC space: 1Ti], but cluster seems to have only 8 cores
    at rust/stackable-cockpit/src/platform/stack/spec.rs:138

   WARN  The stack has the resource requirements [CPU: 71, Memory: 160Gi, PVC space: 1Ti], but cluster seems to have only 47891.8Mi of memory
    at rust/stackable-cockpit/src/platform/stack/spec.rs:138

   WARN  The demo has the resource requirements [CPU: 80, Memory: 200Gi, PVC space: 1Ti], but cluster seems to have only 8 cores
    at rust/stackable-cockpit/src/platform/demo/spec.rs:97

   WARN  The demo has the resource requirements [CPU: 80, Memory: 200Gi, PVC space: 1Ti], but cluster seems to have only 47891.8Mi of memory
    at rust/stackable-cockpit/src/platform/demo/spec.rs:97

Definition of Done Checklist

• Not all of these items are applicable to all PRs, the author should update this template to only leave the boxes in that are relevant
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# Author
- [ ] Changes are OpenShift compatible
- [ ] CRD changes approved
- [ ] Helm chart can be installed and deployed operator works
- [ ] Integration tests passed (for non trivial changes)

# Reviewer
- [ ] Code contains useful comments
- [ ] (Integration-)Test cases added
- [ ] Documentation added or updated
- [ ] Changelog updated
- [ ] Cargo.toml only contains references to git tags (not specific commits or branches)

# Acceptance
- [ ] Feature Tracker has been updated
- [ ] Proper release label has been added

Once the review is done, comment bors r+ (or bors merge) to merge. Further information

[Techassi]

Some suggestions. Nice feature!

[Techassi]

Some suggested improvements: feat/check-demo-resoures...feat/check-demo-resoures-techassi

[sbernauer]

@Techassi did pull in your commit, but also push two other ones. Would be great if you could have a look!

[Techassi]

LGTM. However we need to make sure that all pre-commits are run. Either manually like pre-commit run --all-files or by installing them permanently.

[nightkr]

This feels a bit misleading, since it goes by a very optimistic view of scheduling (one node with no CPU but 1TiB RAM and another node with a 128-core EPYC and no RAM still wouldn't be able to schedule anything useful together).

I can see the value in giving early feedback, but I also wonder if it'd make more sense to focus on surfacing the actual scheduling errors in more discoverable ways.

[sbernauer]

@Techassi thanks for review!
@nightkr good point! There might be cases where the warning is not shown but the demo does not run anyway.
I would argue that their is value in this feature already, as it resolves some issues where users tried to install demos on a too small k8s cluster, which this warning would have catched. We should not see this as an "If no warning is thrown, the demo will definitely run" but more as a "Let's handle 90% of the resource problems by printing a warning and not get asked the same question multiple times, which costs us time"

[nightkr]

Yeah I don't want to block this PR on that.

[sbernauer]

Alright, but it's a good and valid point!
Going forward I would like our stack and demo command waits for our product to be ready. In this place we can show the user the Pod events in the case the stack does not properly start. This could e.g. include 0/10 nodes sufficient memory etc.