Additional fields with defaults to generate.Config object

[muvaf]

Description of changes: As part of the ongoing effort about generating Crossplane AWS Provider, there are some small changes where ACK and Crossplane patterns diverge. In CP, we have all the provider-related fields under spec.forProvider so that it's separate from CP machinery fields. Same with status, we have status.atProvider to differentiate them from other fields. For details, you can see Managed Resources API Patterns Design Doc.

I tried to make the change as least intrusive as possible to the existing mechanisms. Please let me know if you think it could be done in a better way.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[jaypipes]

Hi @muvaf! :) Left a note inline about using the pkg/generate/config.Config struct for this kind of information...

[jaypipes]

Let's make this an attribute of pkg/generate/config.Config instead of a member of the generator itself. This information (the starting prefixes for the Spec and Status fields and the nil find return type) is instructions to the generator on how to handle generated code, so it should go in the Config.

You can also make it something a bit more structured than a map of strings. For example, you might use something like this:

type Config struct {
...
    // Prefix stores any override string prefixes for fields in generated CRDs
    Prefix *PrefixConfig `json:"prefix,omitempty"`
}

type PrefixConfig struct {
    // SpecField stores the string prefix to use for fields in the Spec struct of
    // a CRD. Defaults to `.Spec`
    SpecField string `json:"spec_field"`
    // StatusField stores the string prefix to use for fields in the Status struct of
    // a CRD. Defaults to `.Status`
    StatusField string `json:"status_field"`
}

[muvaf]

Hmm. As it currently stands, the list of strings is here /~https://github.com/aws/aws-controllers-k8s/pull/449/files#diff-bbfadd4328f26a3a50306ade20809a5d15a16a0803dc14d85463e0cce64cb4eaR27

I was kind of hesitant about whether it'd scale to have all custom strings strongly typed in the structs because the list seems to be growing and having them hard-coded works for both ack and crossplane. But making them part of Config makes sense, too, in order to provide some flexibility to the users. I think we can have the current set of strings as hard-coded default for Config object and overwrite what we read from generator.yaml (if any) onto that Config object. Let me know what you think after looking at the current list and I'll make the change.

[jaypipes]

Instead of the map[string]string here, if you went with the PrefixConfig struct I suggest above, you could have little helper methods on CRD like so:

func (crd *CRD) specFieldPrefix() string {
    if crd.cfg == nil || crd.cfg.Prefix == nil {
        return ".Spec"
    }
    return c.Prefix.SpecField
}

func (crd *CRD) statusFieldPrefix() string {
    if crd.cfg == nil || crd.cfg.Prefix == nil {
        return ".Status"
    }
    return c.Prefix.StatusField
}

[muvaf]

I was thinking that for both ack and crossplane, we'd have a hard-coded default Config object and use the generator.yaml as an overlay on top of that Config so we'd make sure there is always a value in those fields.

[muvaf]

@jaypipes Now they are part of the config object except for the APIGroupSuffix because that one is processed in SDKAPI object. I plan to change its value in cmd/crossplane.go after it's initialized. For ACK, nothing really changes.

[muvaf]

If len(resp.CacheClusters) == 0, the for loop won't run at all, meaning found will be false and there is a return statement after the for loop that returns the same answer if found == false. So, behavior shouldn't change when we remove this if block.

[muvaf]

@jaypipes since we know that it will always have some value, what would you think about making r.genCfg a value variable instead of pointer? We wouldn't need to make if r.genCfg != nil check everywhere and run into risk of panicing in places we don't.

[jaypipes]

Awesomeness. You rock @muvaf :)