Fix dashboard log parsing in host

src/Aspire.Hosting/Aspire.Hosting.csproj

@@ -37,6 +37,7 @@
     <Compile Include="$(SharedDir)LaunchProfile.cs" Link="LaunchProfile.cs" />
     <Compile Include="$(SharedDir)LaunchSettingsSerializerContext.cs" Link="LaunchSettingsSerializerContext.cs" />
     <Compile Include="$(SharedDir)SecretsStore.cs" Link="Utils\SecretsStore.cs" />
+    <Compile Include="$(SharedDir)ConsoleLogs\TimestampParser.cs" Link="Utils\ConsoleLogs\TimestampParser.cs" />
   </ItemGroup>
 
   <ItemGroup>

src/Aspire.Hosting/Dashboard/DashboardLifecycleHook.cs

@@ -6,6 +6,7 @@
 using System.Text.Json;
 using System.Text.Json.Nodes;
 using System.Text.Json.Serialization;
+using Aspire.Dashboard.ConsoleLogs;
 using Aspire.Dashboard.Model;
 using Aspire.Hosting.ApplicationModel;
 using Aspire.Hosting.Dcp;
@@ -300,7 +301,13 @@ private static async Task WatchResourceLogsAsync(string dashboardResourceId,
 
                     try
                     {
-                        logMessage = JsonSerializer.Deserialize(logLine.Content, DashboardLogMessageContext.Default.DashboardLogMessage);
+                        var content = logLine.Content;
+                        if (TimestampParser.TryParseConsoleTimestamp(content, out var result))
+                        {
+                            content = result.Value.ModifiedText;
+                        }
+
+                        logMessage = JsonSerializer.Deserialize(content, DashboardLogMessageContext.Default.DashboardLogMessage);
                     }
                     catch (JsonException)
                     {

src/Shared/ConsoleLogs/TimestampParser.cs

@@ -0,0 +1,79 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Diagnostics.CodeAnalysis;
+using System.Globalization;
+using System.Text.RegularExpressions;
+
+namespace Aspire.Dashboard.ConsoleLogs;
+
+internal static partial class TimestampParser
+{
+    private static readonly Regex s_rfc3339RegEx = GenerateRfc3339RegEx();
+
+    public static bool TryParseConsoleTimestamp(string text, [NotNullWhen(true)] out TimestampParserResult? result)
+    {
+        var match = s_rfc3339RegEx.Match(text);
+
+        if (match.Success)
+        {
+            var span = text.AsSpan();
+            var timestamp = span[match.Index..(match.Index + match.Length)];
+
+            ReadOnlySpan<char> content;
+            if (match.Index + match.Length >= span.Length)
+            {
+                content = "";
+            }
+            else
+            {
+                content = span[(match.Index + match.Length)..];
+
+                // Trim whitespace added by logging between timestamp and content.
+                if (char.IsWhiteSpace(content[0]))
+                {
+                    content = content.Slice(1);
+                }
+            }
+
+            result = new(content.ToString(), DateTimeOffset.Parse(timestamp.ToString(), CultureInfo.InvariantCulture));
+            return true;
+        }
+
+        result = default;
+        return false;
+    }
+
+    // Regular Expression for an RFC3339 timestamp, including RFC3339Nano
+    //
+    // Example timestamps:
+    // 2023-10-02T12:56:35.123456789Z
+    // 2023-10-02T13:56:35.123456789+10:00
+    // 2023-10-02T13:56:35.123456789-10:00
+    // 2023-10-02T13:56:35.123456789Z10:00
+    // 2023-10-02T13:56:35.123456Z
+    // 2023-10-02T13:56:35Z
+    //
+    // Explanation:
+    // ^                                                   - Starts the string
+    // (?:\\d{4})                                          - Four digits for the year
+    // -                                                   - Separator for the date
+    // (?:0[1-9]|1[0-2])                                   - Two digits for the month, restricted to 01-12
+    // -                                                   - Separator for the date
+    // (?:0[1-9]|[12][0-9]|3[01])                          - Two digits for the day, restricted to 01-31
+    // [T ]                                                - Literal, separator between date and time, either a T or a space
+    // (?:[01][0-9]|2[0-3])                                - Two digits for the hour, restricted to 00-23
+    // :                                                   - Separator for the time
+    // (?:[0-5][0-9])                                      - Two digits for the minutes, restricted to 00-59
+    // :                                                   - Separator for the time
+    // (?:[0-5][0-9])                                      - Two digits for the seconds, restricted to 00-59
+    // (?:\\.\\d{1,9})                                     - A period and up to nine digits for the partial seconds
+    // Z                                                   - Literal, same as +00:00
+    // (?:[Z+-](?:[01][0-9]|2[0-3]):(?:[0-5][0-9]))        - Time Zone offset, in the form ZHH:MM or +HH:MM or -HH:MM
+    //
+    // Note: (?:) is a non-capturing group, since we don't care about the values, we are just interested in whether or not there is a match
+    [GeneratedRegex("^(?:\\d{4})-(?:0[1-9]|1[0-2])-(?:0[1-9]|[12][0-9]|3[01])T(?:[01][0-9]|2[0-3]):(?:[0-5][0-9]):(?:[0-5][0-9])(?:\\.\\d{1,9})?(?:Z|(?:[Z+-](?:[01][0-9]|2[0-3]):(?:[0-5][0-9])))?")]
+    private static partial Regex GenerateRfc3339RegEx();
+
+    public readonly record struct TimestampParserResult(string ModifiedText, DateTimeOffset Timestamp);
+}

tests/Aspire.Hosting.Tests/Dashboard/DashboardLifecycleHookTests.cs

@@ -0,0 +1,143 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Globalization;
+using System.Text.Json;
+using System.Threading.Channels;
+using Aspire.Hosting.Dashboard;
+using Aspire.Hosting.Dcp;
+using Microsoft.Extensions.Configuration;
+using Microsoft.Extensions.Hosting;
+using Microsoft.Extensions.Logging;
+using Microsoft.Extensions.Logging.Abstractions;
+using Microsoft.Extensions.Logging.Testing;
+using Microsoft.Extensions.Options;
+using Xunit;
+
+namespace Aspire.Hosting.Tests.Dashboard;
+
+public class DashboardLifecycleHookTests
+{
+    [Theory]
+    [MemberData(nameof(Data))]
+    public async Task WatchDashboardLogs_WrittenToHostLoggerFactory(string logMessage, string expectedMessage, string expectedCategory, LogLevel expectedLevel)
+    {
+        // Arrange
+        var testSink = new TestSink();
+        var factory = LoggerFactory.Create(b =>
+        {
+            b.SetMinimumLevel(LogLevel.Trace);
+            b.AddProvider(new TestLoggerProvider(testSink));
+        });
+        var logChannel = Channel.CreateUnbounded<WriteContext>();
+        testSink.MessageLogged += c => logChannel.Writer.TryWrite(c);
+
+        var resourceLoggerService = new ResourceLoggerService();
+        var resourceNotificationService = new ResourceNotificationService(NullLogger<ResourceNotificationService>.Instance, new TestHostApplicationLifetime());
+        var configuration = new ConfigurationBuilder().Build();
+        var hook = new DashboardLifecycleHook(
+            configuration,
+            Options.Create(new DashboardOptions { DashboardPath = "test.dll" }),
+            NullLogger<DistributedApplication>.Instance,
+            new TestDashboardEndpointProvider(),
+            new DistributedApplicationExecutionContext(DistributedApplicationOperation.Run),
+            resourceNotificationService,
+            resourceLoggerService,
+            factory);
+
+        var model = new DistributedApplicationModel(new ResourceCollection());
+        await hook.BeforeStartAsync(model, CancellationToken.None);
+
+        await resourceNotificationService.PublishUpdateAsync(model.Resources.Single(), s => s);
+
+        await foreach (var item in resourceLoggerService.WatchAnySubscribersAsync())
+        {
+            if (item.Name == KnownResourceNames.AspireDashboard && item.AnySubscribers)
+            {
+                break;
+            }
+        }
+
+        // Act
+        var dashboardLogger = resourceLoggerService.GetLogger(KnownResourceNames.AspireDashboard);
+        dashboardLogger.LogError(logMessage);
+
+        // Assert
+        var logContext = await logChannel.Reader.ReadAsync();
+        Assert.Equal(expectedCategory, logContext.LoggerName);
+        Assert.Equal(expectedMessage, logContext.Message);
+        Assert.Equal(expectedLevel, logContext.LogLevel);
+    }
+
+    public static IEnumerable<object[]> Data()
+    {
+        var timestamp = new DateTime(2001, 12, 29, 23, 59, 59, DateTimeKind.Utc);
+        var message = new DashboardLogMessage
+        {
+            LogLevel = LogLevel.Error,
+            Category = "TestCategory",
+            Message = "Hello world",
+            Timestamp = timestamp.ToString(KnownFormats.ConsoleLogsTimestampFormat, CultureInfo.InvariantCulture),
+        };
+        var messageJson = JsonSerializer.Serialize(message, DashboardLogMessageContext.Default.DashboardLogMessage);
+
+        yield return new object[]
+        {
+            $"{DateTime.UtcNow.ToString(KnownFormats.ConsoleLogsTimestampFormat, CultureInfo.InvariantCulture)} {messageJson}",
+            "Hello world",
+            "Aspire.Hosting.Dashboard.TestCategory",
+            LogLevel.Error
+        };
+        yield return new object[]
+        {
+            $"{DateTime.UtcNow.ToString(KnownFormats.ConsoleLogsTimestampFormat, CultureInfo.InvariantCulture)}{messageJson}",
+            "Hello world",
+            "Aspire.Hosting.Dashboard.TestCategory",
+            LogLevel.Error
+        };
+        yield return new object[]
+        {
+            messageJson,
+            "Hello world",
+            "Aspire.Hosting.Dashboard.TestCategory",
+            LogLevel.Error
+        };
+
+        message = new DashboardLogMessage
+        {
+            LogLevel = LogLevel.Critical,
+            Category = "TestCategory.TestSubCategory",
+            Message = "Error message",
+            Exception = new InvalidOperationException("Error!").ToString(),
+            Timestamp = timestamp.ToString(KnownFormats.ConsoleLogsTimestampFormat, CultureInfo.InvariantCulture),
+        };
+        messageJson = JsonSerializer.Serialize(message, DashboardLogMessageContext.Default.DashboardLogMessage);
+
+        yield return new object[]
+        {
+            messageJson,
+            $"Error message{Environment.NewLine}System.InvalidOperationException: Error!",
+            "Aspire.Hosting.Dashboard.TestCategory.TestSubCategory",
+            LogLevel.Critical
+        };
+    }
+
+    private sealed class TestDashboardEndpointProvider : IDashboardEndpointProvider
+    {
+        public Task<string> GetResourceServiceUriAsync(CancellationToken cancellationToken = default)
+        {
+            throw new NotImplementedException();
+        }
+    }
+
+    private sealed class TestHostApplicationLifetime : IHostApplicationLifetime
+    {
+        public CancellationToken ApplicationStarted { get; }
+        public CancellationToken ApplicationStopped { get; }
+        public CancellationToken ApplicationStopping { get; }
+
+        public void StopApplication()
+        {
+        }
+    }
+}