Add whitelist filters to commands

[michaelmdresser]

We currently provide no way to filter output, something like kubectl cost namespace --whitelist ns1,ns2,ns3 which would only display cost data for namespaces ns1, ns2, and ns3.

The backing /aggregatedCostModel API provides filtering and so does the /allocation API.

They do so in different ways, however, making this a little more complicated than just passing a filter through to the API call.

[michaelmdresser]

This should hold until #90 is complete which will simplify this issue substantially.

[Adam-Stack-PM]

@michaelmdresser Closing out as #90 is complete. Please reopen if needed.

[michaelmdresser]

This is an uncompleted improvement, so I'm reopening. #90 just moved the backing API to something that supports filtering. We still need to do the extra bit of work to add filtering flag(s) to kubectl cost.

[michaelmdresser]

Now that we have "v2 filters" I think we can just expose a standard filter string that gets passed to the backend!

Example usage: kubectl cost namespace --filter 'container:"cost-model"'

Filter language docs: https://github.com/kubecost/docs/blob/main/filters-api.md. Shouldn't be too necessary because the BE handles all parsing. Just pass the string to the filter query parameter.

[vladComan0]

I'd like to take a look on this if the issue is still relevant. Note that the filter language docs link does not work anymore.

[michaelmdresser]

This is certainly still relevant. The current docs link is https://docs.kubecost.com/apis/filters-api. It is my strong recommendation to "Just pass the string to the filter query parameter" because the backend APIs already implement the complex logic outlined in the documentation which is standardized in the product.