Redact-fields

Create a RecordPatch that rewrites every field whose key appears in a provided key list. Plain values become placeholder. Secret spans detected by sujy123456/lunasieve are replaced in place, leaving the rest of the field value intact.

Interface

pub fn redact_fields(keys : Array[String], placeholder~ : String = "***") -> RecordPatch {}

input

• keys : Array[String] - Field keys whose values should be redacted.
• placeholder : String - Replacement value written into each matching field.

output

• RecordPatch - Patch that returns a record with matching field values redacted.

Explanation

Detailed rules explaining key parameters and behaviors

• The patch maps over the record field list and rewrites any field whose key is contained in keys.
• Values with no detected secret are replaced entirely by placeholder.
• Detected secret spans are redacted through lunasieve while surrounding text in the same field is kept.
• This helper is useful for masking bundles such as token, password, and secret with one patch.

How to Use

Here are some specific examples provided.

When Mask Several Sensitive Keys

When one logger must protect multiple credentials:

let logger = Logger::new(console_sink())
  .with_patch(redact_fields(["token", "password", "secret"]))

In this example, every matching field value is masked before the sink sees it.

When Share One Custom Mask

When the output should show one explicit policy marker:

let patch = redact_fields([
  "access_key",
  "session_key",
], placeholder="[hidden]")

In this example, all matching fields use the same replacement text.

Error Case

e.g.:

• If keys is empty, the patch behaves like a pass-through field mapper.

• If the same key appears multiple times in keys, matching behavior is unchanged because membership is what matters.

Notes

1. This helper is better than stacking many single-key patches when all keys share the same placeholder policy.

2. It only rewrites structured fields, not text inside the message body.