propagate shared-config and library-option changes between instances

Add a Redis pub/sub invalidation bus, publish from the configuration and library-option write paths, and drop the matching local cache entry on the instances that did not write. No-op without a Redis connection string, and fails open when it is unreachable.
2026-09-20 23:47:21 +10:00
parent ec581b5e5f
commit b662ffa48f
16 changed files with 919 additions and 1 deletions
@@ -0,0 +1,104 @@
+using System;
+using System.Threading.Tasks;
+using Emby.Server.Implementations.Configuration;
+using MediaBrowser.Common.Configuration;
+using Microsoft.Extensions.Logging.Abstractions;
+using StackExchange.Redis;
+using Testcontainers.Redis;
+using Xunit;
+
+namespace Jellyfin.Server.Implementations.Tests.Configuration;
+
+/// <summary>
+/// Round-trips <see cref="RedisConfigurationInvalidationBus"/> through a real Redis, the transport two
+/// replicas actually use to tell each other that the shared configuration directory has changed.
+/// </summary>
+[Trait("Category", "RequiresDocker")]
+public sealed class RedisConfigurationInvalidationBusTests : IAsyncLifetime
+{
+    private readonly RedisContainer _container;
+    private IConnectionMultiplexer? _redis;
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="RedisConfigurationInvalidationBusTests"/> class.
+    /// </summary>
+    public RedisConfigurationInvalidationBusTests()
+    {
+        _container = new RedisBuilder("redis:7-alpine").Build();
+    }
+
+    /// <inheritdoc />
+    public async ValueTask InitializeAsync()
+    {
+        await _container.StartAsync();
+        _redis = await ConnectionMultiplexer.ConnectAsync(_container.GetConnectionString());
+    }
+
+    /// <inheritdoc />
+    public async ValueTask DisposeAsync()
+    {
+        if (_redis is not null)
+        {
+            await _redis.DisposeAsync();
+        }
+
+        await _container.DisposeAsync();
+    }
+
+    /// <summary>
+    /// A notice published by one replica reaches the other, carrying enough to invalidate one entry.
+    /// </summary>
+    /// <returns>A <see cref="Task"/> representing the asynchronous operation.</returns>
+    [Fact]
+    public async Task Publish_ReachesTheOtherInstance()
+    {
+        var received = new TaskCompletionSource<ConfigurationInvalidation>();
+        var instanceA = CreateBus("pod-a");
+        var instanceB = CreateBus("pod-b");
+
+        instanceB.Subscribe(invalidation => received.TrySetResult(invalidation));
+
+        instanceA.Publish(ConfigurationInvalidationScope.LibraryOptions, "/media/movies");
+
+        var invalidation = await received.Task.WaitAsync(TimeSpan.FromSeconds(10), TestContext.Current.CancellationToken);
+        Assert.Equal(ConfigurationInvalidationScope.LibraryOptions, invalidation.Scope);
+        Assert.Equal("/media/movies", invalidation.Target);
+        Assert.Equal("pod-a", invalidation.OriginId);
+    }
+
+    /// <summary>
+    /// The publishing replica has already applied the change to its own cache, so it must not act on its
+    /// own notice and reload what it just wrote.
+    /// </summary>
+    /// <returns>A <see cref="Task"/> representing the asynchronous operation.</returns>
+    [Fact]
+    public async Task Publish_IsNotDeliveredToThePublisher()
+    {
+        var ownNotice = new TaskCompletionSource<ConfigurationInvalidation>();
+        var otherNotice = new TaskCompletionSource<ConfigurationInvalidation>();
+        var instanceA = CreateBus("pod-a");
+        var instanceB = CreateBus("pod-b");
+
+        instanceA.Subscribe(invalidation => ownNotice.TrySetResult(invalidation));
+        instanceB.Subscribe(invalidation => otherNotice.TrySetResult(invalidation));
+
+        instanceA.Publish(ConfigurationInvalidationScope.SystemConfiguration, null);
+
+        // Ordering is per channel, so B having the notice means A would have had it too.
+        await otherNotice.Task.WaitAsync(TimeSpan.FromSeconds(10), TestContext.Current.CancellationToken);
+        Assert.False(ownNotice.Task.IsCompleted);
+    }
+
+    private RedisConfigurationInvalidationBus CreateBus(string originId)
+    {
+        Environment.SetEnvironmentVariable("JELLYFIN_INSTANCE_ID", originId);
+        try
+        {
+            return new RedisConfigurationInvalidationBus(_redis!, NullLogger<RedisConfigurationInvalidationBus>.Instance);
+        }
+        finally
+        {
+            Environment.SetEnvironmentVariable("JELLYFIN_INSTANCE_ID", null);
+        }
+    }
+}