Update ece-manage-capacity for Podman limitation

[frconil]

CPU quotas are not updated, and cannot be set to -1 (disable CPU hard limit) when the underlying container platform is podman.

cc @kunisen

[eedugon]

thanks a lot for bringing this @frconil , and for sharing in private the reasoning behind not being able to customize the CPU quotas on Podman based installations.

As talked I'll tweak a bit the changes and share them with you before merging. I'd like to:

• Add a similar message in https://docs-v3-preview.elastic.dev/elastic/docs-content/pull/1418/deploy-manage/deploy/cloud-enterprise/resource-overrides

• Locate the important banner either at the beginning of the page or in the CPU section, but not in the memory section.

Update: both actions have been discarded, because:

• Resource overrides might not be affected by this (system creates new containers and this limitation might not affect there. pending confirmation).
• The banner at change capacity API (in the memory section) is in the right place, as it's the action that triggers CPU quotas to be re-calculated.

[eedugon]

@kunisen , @frconil , I have a question about this change.

As far as I see in the private slack conversation shared by @frconil , what we want to explain in the docs is that disabling the CPU hard limit in Podman systems is not possible.

But we don't have any document that describes how to tweak the CPU hard limit (which is something we can do only in the advanced editor if i'm not mistaken).

Why are we proposing this change in the doc that talks about Allocators capacity configuration?
I was also thinking about the doc Resource Overrides, but that doc is focused on what the UI allows to override instances, and the UI doesn't show the CPU hard limit enable / disable option.

I'm totally ok with adding a message like:
CPU quotas cannot be disabled (CPU hard limit) or updated when running ECE on Podman.

But we need to ensure the message doesn't create confusion, as a reader running ECE on Docker might ask... and how can be disabled or updated in ECE running on Docker?

Any proposal to make this clearer?

Shouldn't this belong better (perhaps) to the Known Issues of ECE instead of the docs? Like explaining that CPU hard limit disabling doesn't really work on Podman systems?

[eedugon]

Oh, I think the note is applicable to the allocator capacity change that @frconil was suggesting, because if the user changes the capacity of an allocator, the quotas won't be automatically updated for existing instances in Podman systems (is my understanding right?).

[eedugon]

I've created a different PR for a different issue on the same page. We might get a small conflict when merged.

On this, we are still waiting to get some responses from dev, to understand better the implication of this limitation.

The text that I'm planning to propose will be similar to:

When running ECE on Podman, CPU quotas for existing instances cannot be removed (CPU hard limit) or updated. As a result, changing an allocator’s capacity won’t affect the CPU quotas of already running containers.

But we need to get confirmation if that's the expected outcome, like new / future instances really getting updated quota calculations or not.

[eedugon]

I'd like to merge first #1511 and #1507 before deciding final text on this one.