[BUG] flagd doesn't reindex flags on delete

[agardnerIT]

Observed behavior

Changing a flag key while flagd is running doesn't reindex the available flags and the old value is returned until flagd is restarted.

Adding new flags does work

Expected Behavior

Adding and removing flags is entirely dynamic and the JSON file is always the source of truth.

Steps to reproduce

Create a JSON file:

{
    "flags": {
      "foo": {
        "state": "ENABLED",
        "variants": {
          "value": "baz"
        },
        "defaultVariant": "value"
      }
    }
}

Which (correctly) returns baz.

Now change "foo": { to "foo2": { and re-execute the retrieval of foo. I'd expect a "no flag found" error or similar, but I still get baz.

Restart the flagd process and foo is no longer found (which is the correct behaviour).

---

Alternatively, run flagd and (while it is running) add a new flag called foo3. Now get foo3 and that works. Proving that adding dynamically works but deleting doesn't.

[AlexsJones]

Thank you for submitting the bug, I suspect this is to do with the way we merge JSON schema together.

flagd/pkg/eval/json_evaluator.go

Line 40 in e13caea

func (je *JSONEvaluator) SetState(state string) error {

@skyerus @toddbaert thoughts?

[toddbaert]

Ya I think the merge was originally implemented without really thinking about flags being removed.