Truncate regex match failures at an arbitrary 60 characters long

src/transforms/regex_parser.rs

@@ -3,6 +3,7 @@ use crate::event::{self, Event, ValueKind};
 use crate::types::{parse_conversion_map, Conversion};
 use regex::bytes::{CaptureLocations, Regex};
 use serde::{Deserialize, Serialize};
+use std::borrow::Cow;
 use std::collections::HashMap;
 use std::str;
 use string_cache::DefaultAtom as Atom;
@@ -120,7 +121,7 @@ impl Transform for RegexParser {
             } else {
                 warn!(
                     message = "Regex pattern failed to match",
-                    field = &String::from_utf8_lossy(&value)[..],
+                    field = &truncate_string_at(&String::from_utf8_lossy(&value), 60)[..],
                 );
             }
         } else {
@@ -138,6 +139,14 @@ impl Transform for RegexParser {
     }
 }
 
+fn truncate_string_at<'a>(s: &'a str, maxlen: usize) -> Cow<'a, str> {
+    if s.len() >= maxlen {
+        format!("{}[...]", &s[..maxlen - 5]).into()
+    } else {
+        s.into()
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::RegexParserConfig;