Determining if redact has redacted

[byronwolfman]

Our team has been playing around with redact and something we're trying to wrap our heads around is how to determine if redact has modified the input. This is straightforward when the input is a string, but we're not sure what to do with objects. We've tried abusing assert_eq but the docs recommend against using assertions outside of unit tests.

An "easy" way around this problem would be if redact could return two values:

1. The <string | object | array> output as usual
2. A <boolean> indicating whether or not the output has changed

The workaround I can see for now is something along the lines of

redacted = redact(., [r'\d+'])

if encode_json(.) != encode_json(redacted) {
    . = redacted
    .tags = ["redacted:number"]
}

My hesitation is that I'm not sure how expensive it is to marshal JSON twice on every log event, especially as we're operating at a decently large scale. On the other hand, Vector has made me into a Rust true believer, and maybe I'm over-thinking the performance implications.

[jszwedko]

Thanks for opening this request @byronwolfman ! I agree that having an indicator of whether data was redacted or not would be useful.