Add temporary kernel parameter tuning for CloudNativePG Kind cluster

[smartbit]

This PR adds a tuning section for temporary setting kernel parameters required by Kind.

Related issues:

• Increase maxkeys and maxbytes in Known Issues kubernetes-sigs/kind#3806
• 3 control-plane node setup not starting kubernetes-sigs/kind#2744 (comment)'

Alternatively see the more elaborate PR26 that allows permanently setting the kernel parameters. Either of these two PRs can be used, they conflict.

[gbartolini]

@mnencia do you mind checking this with #26 as well?

[ardentperf]

this and #26 seem pretty linux specific - how does it impact mac and windows users? given that the playground README explicitly mentions WSL2, it seems that some level of cross-OS compatibility is intended

even on linux, i feel a bit hesitant about a script that automatically changes kernel settings; that seems risky to do if we're running directly on someone's laptop, hard to know whether it might break something

i think that a better approach is to provide the additional option of using a preconfigured VM (which can run either locally with virtualization software, or on a cloud instance) and the preconfigured VM can have all prerequisites automatically set up for the CNPG playground, including kernel parameters that are needed. with a preconfigured VM we can control the complete operating system environment.

i have the code written and i'm almost ready to submit a PR for this idea 🙂 cc @sxd

[ardentperf]

i think that a better approach is to provide the additional option of using a preconfigured VM (which can run either locally with virtualization software, or on a cloud instance) and the preconfigured VM can have all prerequisites automatically set up for the CNPG playground, including kernel parameters that are needed. with a preconfigured VM we can control the complete operating system environment.

i have the code written and i'm almost ready to submit a PR for this idea

code is available at https://github.com/ardentperf/cnpg-playground if anyone here is curious.

can look at the final commit on the main branch; 99% of the code is isolated in the "lab" subdirectory.