Add semantic meaning to gelf decoded data.

changelog.d/22003-gelf-semantic-meaning.enhancement.md

@@ -0,0 +1 @@
+Set the semantic meaning for `host`, `service` & `timestamp` when decoding gelf messages.

lib/codecs/src/decoding/format/gelf.rs

@@ -64,12 +64,12 @@ impl GelfDeserializerConfig {
             [log_namespace],
         )
         .with_event_field(&owned_value_path!(VERSION), Kind::bytes(), None)
-        .with_event_field(&owned_value_path!(HOST), Kind::bytes(), None)
+        .with_event_field(&owned_value_path!(HOST), Kind::bytes(), Some("host"))
         .with_event_field(&owned_value_path!(SHORT_MESSAGE), Kind::bytes(), None)
         .optional_field(&owned_value_path!(FULL_MESSAGE), Kind::bytes(), None)
-        .optional_field(&owned_value_path!(TIMESTAMP), Kind::timestamp(), None)
+        .optional_field(&owned_value_path!(TIMESTAMP), Kind::timestamp(), Some("timestamp"))
         .optional_field(&owned_value_path!(LEVEL), Kind::integer(), None)
-        .optional_field(&owned_value_path!(FACILITY), Kind::bytes(), None)
+        .optional_field(&owned_value_path!(FACILITY), Kind::bytes(), Some("service"))
         .optional_field(&owned_value_path!(LINE), Kind::integer(), None)
         .optional_field(&owned_value_path!(FILE), Kind::bytes(), None)
         // Every field with an underscore (_) prefix will be treated as an additional field.
@@ -287,6 +287,7 @@ mod tests {
             log.get(HOST),
             Some(&Value::Bytes(Bytes::from_static(b"example.org")))
         );
+        assert_eq!(log.get_by_meaning("host"), Some(&Value::Bytes(Bytes::from_static(b"example.org"))));
         assert_eq!(
             log.get(log_schema().message_key_target_path().unwrap()),
             Some(&Value::Bytes(Bytes::from_static(
@@ -301,11 +302,13 @@ mod tests {
         );
         let dt = DateTime::from_timestamp(1385053862, 307_200_000).expect("invalid timestamp");
         assert_eq!(log.get(TIMESTAMP), Some(&Value::Timestamp(dt)));
+        assert_eq!(log.get_by_meaning("timestamp"), Some(&Value::Timestamp(dt)));
         assert_eq!(log.get(LEVEL), Some(&Value::Integer(1)));
         assert_eq!(
             log.get(FACILITY),
             Some(&Value::Bytes(Bytes::from_static(b"foo")))
         );
+        assert_eq!(log.get_by_meaning("service"), Some(&Value::Bytes(Bytes::from_static(b"foo"))));
         assert_eq!(
             log.get(LINE),
             Some(&Value::Float(ordered_float::NotNan::new(42.0).unwrap()))