refactor: print timestamp in RFC 3339 format

CHANGELOG.md

@@ -40,6 +40,11 @@ All notable changes to this project will be documented in this file.
   * `EnvFilter`'s constructors (`from_env`, etc.) are moved to `EnvFilterBuilder`.
 * Upgrade to opentelemetry 0.31.0.
 
+### Notable changes
+
+* Timestamp format in `TextLayout`, `JsonLayout`, and `LogfmtLayout` is changed from RFC 9557 to RFC 3339 format.
+  * That is, from "2025-01-10T15:22:37.868815+08:00[Asia/Shanghai]" to "2025-01-10T15:22:37.868815+08:00".
+
 ## [0.27.0] 2025-08-18
 
 ### Notable changes

src/diagnostic/fastrace.rs

@@ -21,11 +21,11 @@ use crate::diagnostic::Visitor;
 /// Output format:
 ///
 /// ```text
-/// 2025-01-10T15:22:37.868815+08:00[Asia/Shanghai] ERROR fastrace: fastrace.rs:39 Hello syslog error! trace_id=37f9c45f918cbb477089afb0d7162e7e
-/// 2025-01-10T15:22:37.868890+08:00[Asia/Shanghai]  WARN fastrace: fastrace.rs:40 Hello syslog warn! trace_id=37f9c45f918cbb477089afb0d7162e7e
-/// 2025-01-10T15:22:37.868921+08:00[Asia/Shanghai]  INFO fastrace: fastrace.rs:41 Hello syslog info! trace_id=37f9c45f918cbb477089afb0d7162e7e
-/// 2025-01-10T15:22:37.868949+08:00[Asia/Shanghai] DEBUG fastrace: fastrace.rs:42 Hello syslog debug! trace_id=37f9c45f918cbb477089afb0d7162e7e
-/// 2025-01-10T15:22:37.868976+08:00[Asia/Shanghai] TRACE fastrace: fastrace.rs:43 Hello syslog trace! trace_id=37f9c45f918cbb477089afb0d7162e7e
+/// 2025-01-10T15:22:37.868815+08:00 ERROR fastrace: fastrace.rs:39 Hello syslog error! trace_id=37f9c45f918cbb477089afb0d7162e7e
+/// 2025-01-10T15:22:37.868890+08:00  WARN fastrace: fastrace.rs:40 Hello syslog warn! trace_id=37f9c45f918cbb477089afb0d7162e7e
+/// 2025-01-10T15:22:37.868921+08:00  INFO fastrace: fastrace.rs:41 Hello syslog info! trace_id=37f9c45f918cbb477089afb0d7162e7e
+/// 2025-01-10T15:22:37.868949+08:00 DEBUG fastrace: fastrace.rs:42 Hello syslog debug! trace_id=37f9c45f918cbb477089afb0d7162e7e
+/// 2025-01-10T15:22:37.868976+08:00 TRACE fastrace: fastrace.rs:43 Hello syslog trace! trace_id=37f9c45f918cbb477089afb0d7162e7e
 /// ```
 ///
 /// ## Example

src/layout/google_cloud_logging.rs

@@ -224,6 +224,8 @@ where
 
 impl Layout for GoogleCloudLoggingLayout {
     fn format(&self, record: &Record, diags: &[Box<dyn Diagnostic>]) -> Result<Vec<u8>, Error> {
+        let timestamp = jiff::Timestamp::now();
+
         let mut visitor = KvCollector {
             layout: self,
             payload_fields: BTreeMap::new(),
@@ -243,7 +245,7 @@ impl Layout for GoogleCloudLoggingLayout {
 
         let record_line = RecordLine {
             extra_fields: visitor.payload_fields,
-            timestamp: jiff::Timestamp::now(),
+            timestamp,
             severity: record.level().as_str(),
             message: record.args(),
             labels: visitor.labels,

src/layout/json.rs

@@ -16,9 +16,9 @@ use std::borrow::Cow;
 use std::collections::BTreeMap;
 use std::fmt::Arguments;
 
-use jiff::Timestamp;
 use jiff::Zoned;
 use jiff::tz::TimeZone;
+use jiff::{Timestamp, TimestampDisplayWithOffset};
 use log::Record;
 use serde::Serialize;
 use serde_json::Map;
@@ -102,8 +102,8 @@ impl Visitor for DiagsCollector<'_> {
 
 #[derive(Debug, Clone, Serialize)]
 struct RecordLine<'a> {
-    #[serde(serialize_with = "serialize_time_zone")]
-    timestamp: Zoned,
+    #[serde(serialize_with = "serialize_timestamp")]
+    timestamp: TimestampDisplayWithOffset,
     level: &'a str,
     target: &'a str,
     file: &'a str,
@@ -116,7 +116,10 @@ struct RecordLine<'a> {
     diags: BTreeMap<String, String>,
 }
 
-fn serialize_time_zone<S>(timestamp: &Zoned, serializer: S) -> Result<S::Ok, S::Error>
+fn serialize_timestamp<S>(
+    timestamp: &TimestampDisplayWithOffset,
+    serializer: S,
+) -> Result<S::Ok, S::Error>
 where
     S: serde::Serializer,
 {
@@ -134,6 +137,12 @@ impl Layout for JsonLayout {
     fn format(&self, record: &Record, diags: &[Box<dyn Diagnostic>]) -> Result<Vec<u8>, Error> {
         let diagnostics = diags;
 
+        let time = match self.tz.clone() {
+            None => Zoned::now(),
+            Some(tz) => Timestamp::now().to_zoned(tz),
+        };
+        let timestamp = time.timestamp().display_with_offset(time.offset());
+
         let mut kvs = Map::new();
         let mut kvs_visitor = KvCollector { kvs: &mut kvs };
         record
@@ -148,10 +157,7 @@ impl Layout for JsonLayout {
         }
 
         let record_line = RecordLine {
-            timestamp: match self.tz.clone() {
-                Some(tz) => Timestamp::now().to_zoned(tz),
-                None => Zoned::now(),
-            },
+            timestamp,
             level: record.level().as_str(),
             target: record.target(),
             file: record.file().unwrap_or_default(),

src/layout/logfmt.rs

@@ -117,9 +117,11 @@ impl Visitor for KvFormatter {
 impl Layout for LogfmtLayout {
     fn format(&self, record: &Record, diags: &[Box<dyn Diagnostic>]) -> Result<Vec<u8>, Error> {
         let time = match self.tz.clone() {
-            Some(tz) => Timestamp::now().to_zoned(tz),
             None => Zoned::now(),
+            Some(tz) => Timestamp::now().to_zoned(tz),
         };
+        let time = time.timestamp().display_with_offset(time.offset());
+
         let level = record.level().to_string();
         let target = record.target();
         let file = filename(record);

src/layout/text.rs

@@ -184,9 +184,11 @@ impl Visitor for KvWriter {
 impl Layout for TextLayout {
     fn format(&self, record: &Record, diags: &[Box<dyn Diagnostic>]) -> Result<Vec<u8>, Error> {
         let time = match self.tz.clone() {
-            Some(tz) => Timestamp::now().to_zoned(tz),
             None => Zoned::now(),
+            Some(tz) => Timestamp::now().to_zoned(tz),
         };
+        let time = time.timestamp().display_with_offset(time.offset());
+
         let level = self.format_record_level(record.level());
         let target = record.target();
         let file = filename(record);