[OpAMP] Add remote config settings and ensure correct capabilities

src/OpenTelemetry.OpAmp.Client/.publicApi/PublicAPI.Unshipped.txt

@@ -56,8 +56,14 @@ OpenTelemetry.OpAmp.Client.Settings.OpAmpClientSettings.Identification.set -> vo
 OpenTelemetry.OpAmp.Client.Settings.OpAmpClientSettings.InstanceUid.get -> System.Guid
 OpenTelemetry.OpAmp.Client.Settings.OpAmpClientSettings.InstanceUid.set -> void
 OpenTelemetry.OpAmp.Client.Settings.OpAmpClientSettings.OpAmpClientSettings() -> void
+OpenTelemetry.OpAmp.Client.Settings.OpAmpClientSettings.RemoteConfiguration.get -> OpenTelemetry.OpAmp.Client.Settings.RemoteConfigSettings!
+OpenTelemetry.OpAmp.Client.Settings.OpAmpClientSettings.RemoteConfiguration.set -> void
 OpenTelemetry.OpAmp.Client.Settings.OpAmpClientSettings.ServerUrl.get -> System.Uri!
 OpenTelemetry.OpAmp.Client.Settings.OpAmpClientSettings.ServerUrl.set -> void
+OpenTelemetry.OpAmp.Client.Settings.RemoteConfigSettings
+OpenTelemetry.OpAmp.Client.Settings.RemoteConfigSettings.AcceptsRemoteConfig.get -> bool
+OpenTelemetry.OpAmp.Client.Settings.RemoteConfigSettings.AcceptsRemoteConfig.set -> void
+OpenTelemetry.OpAmp.Client.Settings.RemoteConfigSettings.RemoteConfigSettings() -> void
 override OpenTelemetry.OpAmp.Client.Settings.AnyValueUnion.Equals(object? obj) -> bool
 override OpenTelemetry.OpAmp.Client.Settings.AnyValueUnion.GetHashCode() -> int
 static OpenTelemetry.OpAmp.Client.Settings.AnyValueUnion.operator !=(OpenTelemetry.OpAmp.Client.Settings.AnyValueUnion left, OpenTelemetry.OpAmp.Client.Settings.AnyValueUnion right) -> bool

src/OpenTelemetry.OpAmp.Client/CHANGELOG.md

@@ -15,6 +15,9 @@
 * Expose public `RemoteConfigMessage`.
   ([#3614](https://github.com/open-telemetry/opentelemetry-dotnet-contrib/pull/3614))
 
+* Add settings for remote configuration and update advertised capabilities.
+  ([#3618](https://github.com/open-telemetry/opentelemetry-dotnet-contrib/pull/3618))
+
 ## 0.1.0-alpha.3
 
 Released 2025-Nov-13

src/OpenTelemetry.OpAmp.Client/Internal/FrameBuilder.cs

@@ -132,9 +132,20 @@ IFrameBuilder IFrameBuilder.AddCapabilities()
         this.EnsureInitialized();
 
         // TODO: Update the actual capabilities when features are implemented.
-        this.currentMessage.Capabilities = (ulong)(AgentCapabilities.ReportsStatus
-            | AgentCapabilities.ReportsHealth
-            | AgentCapabilities.ReportsHeartbeat);
+
+        var capabilities = AgentCapabilities.ReportsStatus;
+
+        if (this.settings.Heartbeat.IsEnabled)
+        {
+            capabilities |= AgentCapabilities.ReportsHeartbeat | AgentCapabilities.ReportsHealth;
+        }
+
+        if (this.settings.RemoteConfiguration.AcceptsRemoteConfig)
+        {
+            capabilities |= AgentCapabilities.AcceptsRemoteConfig;
+        }
+
+        this.currentMessage.Capabilities = (ulong)capabilities;
 
         return this;
     }

src/OpenTelemetry.OpAmp.Client/Settings/OpAmpClientSettings.cs

@@ -100,6 +100,11 @@ public Uri ServerUrl
     /// </summary>
     public HeartbeatSettings Heartbeat { get; set; } = new();
 
+    /// <summary>
+    /// Gets or sets the remote configuration settings.
+    /// </summary>
+    public RemoteConfigSettings RemoteConfiguration { get; set; } = new();
+
     /// <summary>
     /// Gets or sets the factory function called to create the <see
     /// cref="HttpClient"/> instance that will be used at runtime to

src/OpenTelemetry.OpAmp.Client/Settings/RemoteConfigSettings.cs

@@ -0,0 +1,19 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+namespace OpenTelemetry.OpAmp.Client.Settings;
+
+/// <summary>
+/// Configuration settings for the remote configuration capability of the client.
+/// </summary>
+public sealed class RemoteConfigSettings
+{
+    /// <summary>
+    /// Gets or sets a value indicating whether the client accepts remote configuration.
+    /// </summary>
+    /// <value>
+    /// <c>true</c> if remote configuration is accepted and should be sent by the server; otherwise, <c>false</c>.
+    /// Default is <c>false</c>.
+    /// </value>
+    public bool AcceptsRemoteConfig { get; set; }
+}

test/OpenTelemetry.OpAmp.Client.Tests/OpAmpClientTests.cs

@@ -1,7 +1,9 @@
 // Copyright The OpenTelemetry Authors
 // SPDX-License-Identifier: Apache-2.0
 
+using OpAmp.Proto.V1;
 using OpenTelemetry.OpAmp.Client.Internal.Services.Heartbeat;
+using OpenTelemetry.OpAmp.Client.Settings;
 using OpenTelemetry.OpAmp.Client.Tests.Mocks;
 using OpenTelemetry.OpAmp.Client.Tests.Tools;
 using Xunit;
@@ -74,4 +76,80 @@ static ulong GetCurrentTimeInNanoseconds()
             return (ulong)DateTimeOffset.UtcNow.ToUnixTimeMilliseconds() * 1_000_000; // Convert to nanoseconds
         }
     }
+
+    [Fact]
+    public async Task DoesNotEmitHeartbeat_WhenDisabled()
+    {
+        using var opAmpServer = new OpAmpFakeHttpServer(false);
+        var opAmpEndpoint = opAmpServer.Endpoint;
+
+        using var mockListener = new MockListener();
+        using var client = new OpAmpClient(o =>
+        {
+            o.ServerUrl = opAmpEndpoint;
+            o.Heartbeat.IsEnabled = false;
+        });
+        client.Subscribe(mockListener);
+
+        await client.StartAsync();
+
+        mockListener.WaitForMessages(TimeSpan.FromSeconds(2));
+
+        var frames = opAmpServer.GetFrames();
+
+        // Only the identification message should be received
+        Assert.Single(frames);
+        Assert.Single(mockListener.Messages);
+
+        await client.StopAsync();
+    }
+
+    [Theory]
+    [ClassData(typeof(CapabilityTestData))]
+    internal async Task SendsExpectedCapabilities(
+        Action<OpAmpClientSettings> configure,
+        IEnumerable<AgentCapabilities> expectedCapabilities,
+        IEnumerable<AgentCapabilities> notExpectedCapabilities)
+    {
+        using var opAmpServer = new OpAmpFakeHttpServer(false);
+        var opAmpEndpoint = opAmpServer.Endpoint;
+        configure += o => o.ServerUrl = opAmpEndpoint;
+
+        using var mockListener = new MockListener();
+        using var client = new OpAmpClient(configure);
+        client.Subscribe(mockListener);
+
+        await client.StartAsync();
+
+        var frames = opAmpServer.GetFrames();
+
+        Assert.True(frames.Count >= 1, "Expecting at least one server frame.");
+
+        var identificationFrame = frames[0];
+        var capabilities = (AgentCapabilities)identificationFrame.Capabilities;
+
+        foreach (var expectedCapability in expectedCapabilities)
+        {
+            Assert.True(capabilities.HasFlag(expectedCapability), $"Expected capabilities to include {expectedCapability}.");
+        }
+
+        foreach (var notExpectedCapability in notExpectedCapabilities)
+        {
+            Assert.False(capabilities.HasFlag(notExpectedCapability), $"Expected capabilities not to include {notExpectedCapability}.");
+        }
+
+        await client.StopAsync();
+    }
+
+    internal class CapabilityTestData
+        : TheoryData<Action<OpAmpClientSettings>, IEnumerable<AgentCapabilities>, IEnumerable<AgentCapabilities>>
+    {
+        public CapabilityTestData()
+        {
+            this.Add(o => o.Heartbeat.IsEnabled = false, [], [AgentCapabilities.ReportsHeartbeat, AgentCapabilities.ReportsHealth]);
+            this.Add(o => o.Heartbeat.IsEnabled = true, [AgentCapabilities.ReportsHeartbeat, AgentCapabilities.ReportsHealth], []);
+            this.Add(o => o.RemoteConfiguration.AcceptsRemoteConfig = true, [AgentCapabilities.AcceptsRemoteConfig], []);
+            this.Add(o => o.RemoteConfiguration.AcceptsRemoteConfig = false, [], [AgentCapabilities.AcceptsRemoteConfig]);
+        }
+    }
 }

test/OpenTelemetry.OpAmp.Client.Tests/PlainHttpTransportTests.cs

@@ -42,8 +42,8 @@ public async Task PlainHttpTransport_SendReceiveCommunication(bool useSmallPacke
         var clientReceivedFrames = mockListener.Messages;
         var receivedTextData = clientReceivedFrames.First().CustomMessage.Data.ToStringUtf8();
 
-        Assert.Single(serverReceivedFrames);
-        Assert.Equal(mockFrame.Uid, serverReceivedFrames.First().InstanceUid);
+        var frame = Assert.Single(serverReceivedFrames);
+        Assert.Equal(mockFrame.Uid, frame.InstanceUid);
 
         Assert.Single(clientReceivedFrames);
         Assert.StartsWith("This is a mock server frame for testing purposes.", receivedTextData);
@@ -71,7 +71,6 @@ public async Task PlainHttpTransport_UsesConfiguredHttpClientFactory()
         frameProcessor.Subscribe(mockListener);
 
         var httpTransport = new PlainHttpTransport(settings, frameProcessor);
-
         var mockFrame = FrameGenerator.GenerateMockAgentFrame(false);
 
         // Act

test/OpenTelemetry.OpAmp.Client.Tests/Tools/OpAmpFakeHttpServer.cs

@@ -45,7 +45,7 @@ public OpAmpFakeHttpServer(bool useSmallPackets)
 
     public Uri Endpoint { get; }
 
-    public IReadOnlyCollection<AgentToServer> GetFrames()
+    public IReadOnlyList<AgentToServer> GetFrames()
     {
         return this.frames.ToArray();
     }