Support Kubernetes-style quantity suffixes

[kwohlfahrt]

Please describe your feature request.

I want to use yq to work with Kubernetes resources, where quantities are frequently expressed with a suffix. The formats are:

• Integers, possibly stringified (e.g. "3" or 3)
• "1m" for "milli", equal to 0.001
• "1k" for "k", equal to 1000, as well as M, G, T, P, and E
• "1Ki" for 2^10, equal to 1024, similarly Mi, Gi, etc

Note k and Ki differ in capitalization, otherwise it's just an additional i suffix.

Describe the solution you'd like

I would like a function to convert to and from the suffixed units. Integer milli quantities are probably the best solution, as it preserves the exact value.

- resources:
    cpu: 200m
    memory: 300Mi
- resources:
    cpu: "3"
    memory: 512M

And we run a command:

yq '{"cpu": (.[].resources.cpu | tomillis) as $item ireduce (0; . + $item) | frommillis, "memory": (.[].resources.memory | tomillis) as $item ireduce (0; . + $item) | frommillis}'

it could output

cpu: 3200m
memory: 807200Ki

Note memory only simplifies to the nearest Ki, so the output unit is different from the input.

Describe alternatives you've considered

We could also convert to/from float, but I'd be worried about loss of precision.

Additional context

Happy to work on implementing this.