Limit number of console log messages retained in dashboard process (#4936)

* Add LogEntries.MaximumEntryCount

Inserting log entries such that the total exceeds this amount results in the earliest log entry being dropped.

* Fix typo

* Use compound assignment

* Remove redundant arguments

These always have the same value and can be captured along with other captured state.

* Remove redundant using alias

* Control console log history limit via configuration

* Rename symbol

* Update doc comment

* Use CircularBuffer and inject config

* Define and use central value for config key name

Author: drewnoakes

src/Aspire.Dashboard/Authentication/OpenIdConnect/AuthorizationPolicyBuilderExtensions.cs

@@ -2,7 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using Microsoft.AspNetCore.Authorization;
-using OpenIdConnectOptions = Aspire.Dashboard.Configuration.OpenIdConnectOptions;
+using Aspire.Dashboard.Configuration;
 
 namespace Aspire.Dashboard.Authentication.OpenIdConnect;
 

src/Aspire.Dashboard/Components/Controls/LogViewer.razor.cs

@@ -73,10 +73,7 @@ internal async Task SetLogSourceAsync(string resourceName, IAsyncEnumerable<IRea
             {
                 // Keep track of the base line number to ensure that we can calculate the line number of each log entry.
                 // This becomes important when the total number of log entries exceeds the limit and is truncated.
-                if (ViewModel.LogEntries.BaseLineNumber is null)
-                {
-                    ViewModel.LogEntries.BaseLineNumber = lineNumber;
-                }
+                ViewModel.LogEntries.BaseLineNumber ??= lineNumber;
 
                 ViewModel.LogEntries.InsertSorted(logParser.CreateLogEntry(content, isErrorOutput));
             }

src/Aspire.Dashboard/Components/Pages/ConsoleLogs.razor.cs

@@ -120,7 +120,7 @@ async Task TrackResourceSnapshotsAsync()
             {
                 await foreach (var changes in subscription.WithCancellation(_resourceSubscriptionCancellation.Token).ConfigureAwait(false))
                 {
-                    // TODO: This could be updated to be more efficent.
+                    // TODO: This could be updated to be more efficient.
                     // It should apply on the resource changes in a batch and then update the UI.
                     foreach (var (changeType, resource) in changes)
                     {

src/Aspire.Dashboard/Configuration/DashboardOptions.cs

@@ -131,6 +131,16 @@ public sealed class FrontendOptions
     public string? EndpointUrls { get; set; }
     public FrontendAuthMode? AuthMode { get; set; }
     public string? BrowserToken { get; set; }
+
+    /// <summary>
+    /// Gets and sets an optional limit on the number of console log messages to be retained in the viewer.
+    /// </summary>
+    /// <remarks>
+    /// The viewer will retain at most this number of log messages. When the limit is reached, the oldest messages will be removed.
+    /// Defaults to 10,000, which matches the default used in the app host's circular buffer, on the publish side.
+    /// </remarks>
+    public int MaxConsoleLogCount { get; set; } = 10_000;
+
     public OpenIdConnectOptions OpenIdConnect { get; set; } = new();
 
     public byte[]? GetBrowserTokenBytes() => _browserTokenBytes;

src/Aspire.Dashboard/Configuration/ValidateDashboardOptions.cs

@@ -55,6 +55,11 @@ public ValidateOptionsResult Validate(string? name, DashboardOptions options)
                 break;
         }
 
+        if (options.Frontend.MaxConsoleLogCount <= 0)
+        {
+            errorMessages.Add($"{DashboardConfigNames.DashboardFrontendMaxConsoleLogCountName.ConfigKey} must be greater than zero.");
+        }
+
         if (!options.Otlp.TryParseOptions(out var otlpParseErrorMessage))
         {
             errorMessages.Add(otlpParseErrorMessage);

src/Aspire.Dashboard/ConsoleLogs/LogEntries.cs

@@ -3,12 +3,13 @@
 
 using System.Diagnostics;
 using Aspire.Dashboard.Model;
+using Aspire.Dashboard.Otlp.Storage;
 
 namespace Aspire.Dashboard.ConsoleLogs;
 
-public sealed class LogEntries
+public sealed class LogEntries(int maximumEntryCount)
 {
-    private readonly List<LogEntry> _logEntries = new();
+    private readonly CircularBuffer<LogEntry> _logEntries = new(maximumEntryCount);
 
     public int? BaseLineNumber { get; set; }
 
@@ -28,7 +29,7 @@ public void InsertSorted(LogEntry logEntry)
 
                 if (current.Id == logEntry.ParentId && logEntry.LineIndex - 1 == current.LineIndex)
                 {
-                    InsertLogEntry(_logEntries, rowIndex + 1, logEntry);
+                    InsertAt(rowIndex + 1);
                     return;
                 }
             }
@@ -45,17 +46,17 @@ public void InsertSorted(LogEntry logEntry)
 
                 if (currentTimestamp != null && currentTimestamp <= logEntry.Timestamp)
                 {
-                    InsertLogEntry(_logEntries, rowIndex + 1, logEntry);
+                    InsertAt(rowIndex + 1);
                     return;
                 }
             }
         }
 
         // If we didn't find a place to insert then append it to the end. This happens with the first entry, but
         // could also happen if the logs don't have recognized timestamps.
-        InsertLogEntry(_logEntries, _logEntries.Count, logEntry);
+        InsertAt(_logEntries.Count);
 
-        void InsertLogEntry(List<LogEntry> logEntries, int index, LogEntry logEntry)
+        void InsertAt(int index)
         {
             // Set the line number of the log entry.
             if (index == 0)
@@ -65,15 +66,16 @@ void InsertLogEntry(List<LogEntry> logEntries, int index, LogEntry logEntry)
             }
             else
             {
-                logEntry.LineNumber = logEntries[index - 1].LineNumber + 1;
+                logEntry.LineNumber = _logEntries[index - 1].LineNumber + 1;
             }
 
-            logEntries.Insert(index, logEntry);
+            // Insert the entry.
+            _logEntries.Insert(index, logEntry);
 
             // If a log entry isn't inserted at the end then update the line numbers of all subsequent entries.
-            for (var i = index + 1; i < logEntries.Count; i++)
+            for (var i = index + 1; i < _logEntries.Count; i++)
             {
-                logEntries[i].LineNumber++;
+                _logEntries[i].LineNumber++;
             }
         }
     }

src/Aspire.Dashboard/Model/LogViewerViewModel.cs

@@ -1,13 +1,14 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using Aspire.Dashboard.Configuration;
 using Aspire.Dashboard.ConsoleLogs;
+using Microsoft.Extensions.Options;
 
 namespace Aspire.Dashboard.Model;
 
-public class LogViewerViewModel
+public class LogViewerViewModel(IOptions<DashboardOptions> options)
 {
-    public LogEntries LogEntries { get; } = new();
+    public LogEntries LogEntries { get; } = new(options.Value.Frontend.MaxConsoleLogCount);
     public string? ResourceName { get; set; }
-
 }

src/Aspire.Dashboard/README.md

@@ -63,6 +63,10 @@ Set `Dashboard:Frontend:AuthMode` to `OpenIdConnect`, then add the following con
 - `Dashboard:Frontend:OpenIdConnect:RequiredClaimType` specifies the (optional) claim that be present for authorized users. Defaults to empty.
 - `Dashboard:Frontend:OpenIdConnect:RequiredClaimValue` specifies the (optional) value of the required claim. Only used if `Dashboard:Frontend:OpenIdConnect:RequireClaimType` is also specified. Defaults to empty.
 
+#### Memory limits
+
+- `Dashboard:Frontend:MaxConsoleLogCount` specifies the (optional) maximum number of console log messages to keep in memory. Defaults to 10,000. When the limit is reached, the oldest messages are removed.
+
 ### OTLP authentication
 
 The OTLP endpoint can be secured with [client certificate](https://learn.microsoft.com/aspnet/core/security/authentication/certauth) or API key authentication.

src/Shared/DashboardConfigNames.cs

@@ -17,6 +17,7 @@ internal static class DashboardConfigNames
     public static readonly ConfigName DashboardOtlpSecondaryApiKeyName = new("Dashboard:Otlp:SecondaryApiKey", "DASHBOARD__OTLP__SECONDARYAPIKEY");
     public static readonly ConfigName DashboardFrontendAuthModeName = new("Dashboard:Frontend:AuthMode", "DASHBOARD__FRONTEND__AUTHMODE");
     public static readonly ConfigName DashboardFrontendBrowserTokenName = new("Dashboard:Frontend:BrowserToken", "DASHBOARD__FRONTEND__BROWSERTOKEN");
+    public static readonly ConfigName DashboardFrontendMaxConsoleLogCountName = new("Dashboard:Frontend:MaxConsoleLogCount", "DASHBOARD__FRONTEND__MAXCONSOLELOGCOUNT");
     public static readonly ConfigName ResourceServiceClientAuthModeName = new("Dashboard:ResourceServiceClient:AuthMode", "DASHBOARD__RESOURCESERVICECLIENT__AUTHMODE");
     public static readonly ConfigName ResourceServiceClientApiKeyName = new("Dashboard:ResourceServiceClient:ApiKey", "DASHBOARD__RESOURCESERVICECLIENT__APIKEY");
 }

tests/Aspire.Dashboard.Tests/ConsoleLogsTests/LogEntriesTests.cs

@@ -13,7 +13,7 @@ public class LogEntriesTests
     public void InsertSorted_OutOfOrderWithSameTimestamp_ReturnInOrder()
     {
         // Arrange
-        var logEntries = new LogEntries();
+        var logEntries = new LogEntries(maximumEntryCount: int.MaxValue);
 
         var timestamp = new DateTimeOffset(2024, 6, 25, 15, 59, 0, TimeSpan.Zero);
 
@@ -31,4 +31,44 @@ public void InsertSorted_OutOfOrderWithSameTimestamp_ReturnInOrder()
             l => Assert.Equal("2", l.Content),
             l => Assert.Equal("3", l.Content));
     }
+
+    [Fact]
+    public void InsertSorted_TrimsToMaximumEntryCount_Ordered()
+    {
+        // Arrange
+        var logEntries = new LogEntries(maximumEntryCount: 2) { BaseLineNumber = 1 };
+
+        var timestamp = DateTimeOffset.UtcNow;
+
+        // Act
+        logEntries.InsertSorted(new LogEntry { Timestamp = timestamp.AddSeconds(1), Content = "1" });
+        logEntries.InsertSorted(new LogEntry { Timestamp = timestamp.AddSeconds(2), Content = "2" });
+        logEntries.InsertSorted(new LogEntry { Timestamp = timestamp.AddSeconds(3), Content = "3" });
+
+        // Assert
+        var entries = logEntries.GetEntries();
+        Assert.Collection(entries,
+            l => Assert.Equal("2", l.Content),
+            l => Assert.Equal("3", l.Content));
+    }
+
+    [Fact]
+    public void InsertSorted_TrimsToMaximumEntryCount_OutOfOrder()
+    {
+        // Arrange
+        var logEntries = new LogEntries(maximumEntryCount: 2) { BaseLineNumber = 1 };
+
+        var timestamp = DateTimeOffset.UtcNow;
+
+        // Act
+        logEntries.InsertSorted(new LogEntry { Timestamp = timestamp.AddSeconds(1), Content = "1" });
+        logEntries.InsertSorted(new LogEntry { Timestamp = timestamp.AddSeconds(3), Content = "3" });
+        logEntries.InsertSorted(new LogEntry { Timestamp = timestamp.AddSeconds(2), Content = "2" });
+
+        // Assert
+        var entries = logEntries.GetEntries();
+        Assert.Collection(entries,
+            l => Assert.Equal("2", l.Content),
+            l => Assert.Equal("3", l.Content));
+    }
 }