feat: Validate k8s resource requirements for CPU, Memory and Ephemeral Volumes

[KengoA]

Pull Request Checklist

• Fixes Robust validation for k8s resource requirements #943
• Tests added
• Documentation/examples added
• Good commit messages and/or PR title

Description of PR

Currently, resource requirements are only partially validated for binary units with hera.workflows.validators.validate_storage_units() function for string values. The current implementaion misses some edge cases where the input is missing numerial values and only the unit is provided (i.e. "Ki" or "Mi"), and the comparison between request and limit is limited to int values for cpu_request and cpu_limit.

This PR

• Refactors validation for binary units
  • Fixes float values not compared for CPU requests/limits
• Adds validation for decimal units representation of CPU requests/limits in string format
  • Supported units are based on https://github.com/kubernetes/apimachinery/blob/dc7e034c86479d49be4b0eefad307621e10caa0e/pkg/api/resource/quantity.go#L48
  • Units are optional and "0.5" and "1" are still valid
• Adds converters from decimal and binary units to float values
• Adds comparison of decimal units (CPU) and binary units (Memory and Ephemeral Volumes) representations of resource requirements
• Adds tests for hera/workflows/resources.py

[codecov]

Codecov Report

Attention: 4 lines in your changes are missing coverage. Please review.

Comparison is base (b3fc378) 80.7% compared to head (154d9fe) 81.0%.

Files	Patch %	Lines
src/hera/workflows/resources.py	78.9%	0 Missing and 4 partials ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##            main    #944     +/-   ##
=======================================
+ Coverage   80.7%   81.0%   +0.2%     
=======================================
  Files         50      51      +1     
  Lines       3908    3942     +34     
  Branches     793     801      +8     
=======================================
+ Hits        3157    3195     +38     
+ Misses       564     561      -3     
+ Partials     187     186      -1     

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[KengoA]

renamed from validate_storage_units to validate_binary_units as this applies to memory and ephemeral volumes

[flaviuvadan]

Unfortunately this helper is public and we don't know who might use it outside of the core of Hera. Any chance we can leave validate_storage_units(value: str) -> None as public and internally it passes the value to validate_binary_units? That way we get the new function with improved functionality while maintaining backwards compatibility

[KengoA]

Thanks for your quick review!

In the commit below I kept the public function and used alias to refer to the _validate_binary_units, which is now made private so that we can change the implementaion later if necessary.

To avoid confusion and also to make the function names consistent, other function names are now named more explicitly for their use cases (validate_storage_units, validate_cpu_units, validate_memory_units) as well as converters.

31184f8

[flaviuvadan]

The supported units are ['m', 'k', 'M', 'G', 'T', 'P', 'E'].

Small - maybe this can go into the docstring of value

[KengoA]

Good point! I added supported units in docstrings for validators and converters in the value section 154d9fe.

[flaviuvadan]

Thanks for the first time contribution @KengoA! This is really great :) Left some small feedback on backwards compatibility and docs. The rest looks great

[elliotgunton]

LGTM! Thank you @KengoA 🚀