feat: adds derive from cel query readiness policy

[zach-source]

Description of your changes

Adds new readiness policy called "DeriveFromCelQuery". This policy allows the use of a cel query to check if an object is ready. This is handy to check conditions on objects with non-standard methods of determining if it ready such as the argocd applictation object.

Probably closes #192

I have:

• Read and followed Crossplane's contribution process.
• Run make reviewable test to ensure this PR is ready for review.

How has this code been tested

I've written several test caes that cover the usage of the new feature.

[bobh66]

@zach-source this looks great - do you have an example of how to reference a status condition with a specific type in a CEL query? I have been looking at CEL examples and I haven't found an equivalent syntax to the JSONPath $.status.conditions[?(@.type=="Completed")].status syntax.

[bobh66]

@zach-source this looks great - do you have an example of how to reference a status condition with a specific type in a CEL query? I have been looking at CEL examples and I haven't found an equivalent syntax to the JSONPath $.status.conditions[?(@.type=="Completed")].status syntax.

I think I figured it out:

status.conditions.exists(w, w.type=='Foo' && w.status == 'True')

[zach-source]

Ah yea, exactly. And you can combine them if you want multiple. I've pushed up changes to make it pass all the reviewable checks. It's been a minute since I worked on a provider and I always have a hard time getting that submodule to sync correctly. You can see the list of all the available macros here: https://github.com/google/cel-spec/blob/master/doc/langdef.md#macros

I'll add a test case for ya.

[bobh66]

@zach-source Please run go mod tidy and make generate and commit the results.

[zach-source]

Should be good to go now @bobh66

[bobh66]

@turkenh can you take a look at this? It would be great to get this into the next release if possible - thanks!

[phisco]

Looking good! A few minor comments

[zach-source]

Looking good! A few minor comments

Thanks for the review - I'll do a bit of work on it this weekend and push it up. Probably tomorrow.

[zach-source]

@phisco comments have been addressed.

[phisco]

Looking good! just a few small nits, we can address them in a follow up pr if needed

[zach-source]

@phisco Added your recommended changes/nits.