Support UtcTimestamp token in output template (new since Serilog 4.0)

src/Serilog.Sinks.Console/Sinks/SystemConsole/Output/OutputTemplateRenderer.cs

@@ -68,7 +68,11 @@ public OutputTemplateRenderer(ConsoleTheme theme, string outputTemplate, IFormat
                 }
                 else if (pt.PropertyName == OutputProperties.TimestampPropertyName)
                 {
-                    renderers.Add(new TimestampTokenRenderer(theme, pt, formatProvider));
+                    renderers.Add(new TimestampTokenRenderer(theme, pt, formatProvider, convertToUtc: false));
+                }
+                else if (pt.PropertyName == OutputProperties.UtcTimestampPropertyName)
+                {
+                    renderers.Add(new TimestampTokenRenderer(theme, pt, formatProvider, convertToUtc: true));
                 }
                 else if (pt.PropertyName == OutputProperties.PropertiesPropertyName)
                 {

src/Serilog.Sinks.Console/Sinks/SystemConsole/Output/TimestampTokenRenderer.cs

@@ -26,63 +26,85 @@ class TimestampTokenRenderer : OutputTemplateTokenRenderer
 {
     readonly ConsoleTheme _theme;
     readonly PropertyToken _token;
+    readonly string? _format;
     readonly IFormatProvider? _formatProvider;
+    readonly bool _convertToUtc;
 
-    public TimestampTokenRenderer(ConsoleTheme theme, PropertyToken token, IFormatProvider? formatProvider)
+    public TimestampTokenRenderer(ConsoleTheme theme, PropertyToken token, IFormatProvider? formatProvider, bool convertToUtc)
     {
-            _theme = theme;
-            _token = token;
-            _formatProvider = formatProvider;
-        }
+        _theme = theme;
+        _token = token;
+        _format = token.Format;
+        _formatProvider = formatProvider;
+        _convertToUtc = convertToUtc;
+    }
 
     public override void Render(LogEvent logEvent, TextWriter output)
     {
-            var sv = new DateTimeOffsetValue(logEvent.Timestamp);
-
-            var _ = 0;
-            using (_theme.Apply(output, ConsoleThemeStyle.SecondaryText, ref _))
+        var _ = 0;
+        using (_theme.Apply(output, ConsoleThemeStyle.SecondaryText, ref _))
+        {
+            if (_token.Alignment is null)
             {
-                if (_token.Alignment is null)
-                {
-                    sv.Render(output, _token.Format, _formatProvider);
-                }
-                else
-                {
-                    var buffer = new StringWriter();
-                    sv.Render(buffer, _token.Format, _formatProvider);
-                    var str = buffer.ToString();
-                    Padding.Apply(output, str, _token.Alignment);
-                }
+                Render(output, logEvent.Timestamp);
+            }
+            else
+            {
+                var buffer = new StringWriter();
+                Render(buffer, logEvent.Timestamp);
+                var str = buffer.ToString();
+                Padding.Apply(output, str, _token.Alignment);
             }
         }
+    }
 
-    readonly struct DateTimeOffsetValue
+    private void Render(TextWriter output, DateTimeOffset timestamp)
     {
-        public DateTimeOffsetValue(DateTimeOffset value)
-        {
-                Value = value;
-            }
+        // When a DateTimeOffset is converted to a string, the default format automatically adds the "+00:00" explicit offset to the output string.
+        // As the TimestampTokenRenderer is also used for rendering the UtcTimestamp which is always in UTC by definition, the +00:00 suffix should be avoided.
+        // This is done using the same approach as Serilog's MessageTemplateTextFormatter. In case output should be converted to UTC, in order to avoid a zone specifier,
+        // the DateTimeOffset is converted to a DateTime which then renders as expected.
 
-        public DateTimeOffset Value { get; }
+        var custom = (ICustomFormatter?)_formatProvider?.GetFormat(typeof(ICustomFormatter));
+        if (custom != null)
+        {
+            output.Write(custom.Format(_format, _convertToUtc ? timestamp.UtcDateTime : timestamp, _formatProvider));
+            return;
+        }
 
-        public void Render(TextWriter output, string? format = null, IFormatProvider? formatProvider = null)
+        if (_convertToUtc)
         {
-            var custom = (ICustomFormatter?)formatProvider?.GetFormat(typeof(ICustomFormatter));
-            if (custom != null)
-            {
-                output.Write(custom.Format(format, Value, formatProvider));
-                return;
-            }
+            RenderDateTime(output, timestamp.UtcDateTime);
+        }
+        else
+        {
+            RenderDateTimeOffset(output, timestamp);
+        }
+    }
 
+    private void RenderDateTimeOffset(TextWriter output, DateTimeOffset timestamp)
+    {
 #if FEATURE_SPAN
-                Span<char> buffer = stackalloc char[32];
-                if (Value.TryFormat(buffer, out int written, format, formatProvider ?? CultureInfo.InvariantCulture))
-                    output.Write(buffer.Slice(0, written));
-                else
-                    output.Write(Value.ToString(format, formatProvider ?? CultureInfo.InvariantCulture));
+        Span<char> buffer = stackalloc char[32];
+        if (timestamp.TryFormat(buffer, out int written, _format, _formatProvider ?? CultureInfo.InvariantCulture))
+            output.Write(buffer.Slice(0, written));
+        else
+            output.Write(timestamp.ToString(_format, _formatProvider ?? CultureInfo.InvariantCulture));
 #else
-            output.Write(Value.ToString(format, formatProvider ?? CultureInfo.InvariantCulture));
+            output.Write(timestamp.ToString(_format, _formatProvider ?? CultureInfo.InvariantCulture));
+#endif
+    }
+
+    private void RenderDateTime(TextWriter output, DateTime utcTimestamp)
+    {
+#if FEATURE_SPAN
+        Span<char> buffer = stackalloc char[32];
+        if (utcTimestamp.TryFormat(buffer, out int written, _format, _formatProvider ?? CultureInfo.InvariantCulture))
+            output.Write(buffer.Slice(0, written));
+        else
+            output.Write(utcTimestamp.ToString(_format, _formatProvider ?? CultureInfo.InvariantCulture));
+#else
+            output.Write(utcTimestamp.ToString(_format, _formatProvider ?? CultureInfo.InvariantCulture));
 #endif
-        }
     }
 }

test/Serilog.Sinks.Console.Tests/Output/OutputTemplateRendererTests.cs

@@ -400,4 +400,36 @@ public void TraceAndSpanAreIncludedWhenPresent()
         formatter.Format(evt, sw);
         Assert.Equal($"{traceId}/{spanId}", sw.ToString());
     }
+
+    [Theory]
+    [InlineData("{Timestamp}", "09/03/2024 14:15:16 +02:00")] // Default Format
+    [InlineData("{Timestamp:o}", "2024-09-03T14:15:16.0790000+02:00")] // Round-trip Standard Format String
+    [InlineData("{Timestamp:yyyy-MM-dd HH:mm:ss}", "2024-09-03 14:15:16")] // Custom Format String
+    public void TimestampTokenRendersLocalTime(string actualToken, string expectedOutput)
+    {
+        var logTimestampWithTimeZoneOffset = DateTimeOffset.Parse("2024-09-03T14:15:16.079+02:00", CultureInfo.InvariantCulture);
+        var formatter = new OutputTemplateRenderer(ConsoleTheme.None, actualToken, CultureInfo.InvariantCulture);
+        var evt = new LogEvent(logTimestampWithTimeZoneOffset, LogEventLevel.Debug, null,
+            new MessageTemplate(Enumerable.Empty<MessageTemplateToken>()), Enumerable.Empty<LogEventProperty>());
+        var sw = new StringWriter();
+        formatter.Format(evt, sw);
+        // expect time in local time, unchanged from the input, the +02:00 offset should not affect the output
+        Assert.Equal(expectedOutput, sw.ToString());
+    }
+
+    [Theory]
+    [InlineData("{UtcTimestamp}", "09/03/2024 12:15:16")] // Default Format
+    [InlineData("{UtcTimestamp:o}", "2024-09-03T12:15:16.0790000Z")] // Round-trip Standard Format String
+    [InlineData("{UtcTimestamp:yyyy-MM-dd HH:mm:ss}", "2024-09-03 12:15:16")] // Custom Format String
+    public void UtcTimestampTokenRendersUtcTime(string actualToken, string expectedOutput)
+    {
+        var logTimestampWithTimeZoneOffset = DateTimeOffset.Parse("2024-09-03T14:15:16.079+02:00", CultureInfo.InvariantCulture);
+        var formatter = new OutputTemplateRenderer(ConsoleTheme.None, actualToken, CultureInfo.InvariantCulture);
+        var evt = new LogEvent(logTimestampWithTimeZoneOffset, LogEventLevel.Debug, null,
+            new MessageTemplate(Enumerable.Empty<MessageTemplateToken>()), Enumerable.Empty<LogEventProperty>());
+        var sw = new StringWriter();
+        formatter.Format(evt, sw);
+        // expect time in UTC, the +02:00 offset must be applied to adjust the hour
+        Assert.Equal(expectedOutput, sw.ToString());
+    }
 }