Add grpc keep alive

Signed-off-by: Jonathan Collinge <[email protected]>

Author: jjcollinge

src/Dapr.Workflow/DaprWorkflowClientBuilderFactory.cs

@@ -64,6 +64,8 @@ public void CreateClientBuilder(IServiceCollection services, Action<WorkflowRunt
                 HttpClient = httpClient
             };
 
+            GrpcKeepAlive.Configure(options, channelOptions);
+
             builder.UseGrpc(GrpcChannel.ForAddress(grpcEndpoint, channelOptions));
             builder.RegisterDirectly();
         });
@@ -90,6 +92,8 @@ public void CreateClientBuilder(IServiceCollection services, Action<WorkflowRunt
                     HttpClient = httpClient
                 };
 
+                GrpcKeepAlive.Configure(options, channelOptions);
+
                 builder.UseGrpc(GrpcChannel.ForAddress(grpcEndpoint, channelOptions));
             }
             else

src/Dapr.Workflow/GrpcKeepAlive.cs

@@ -0,0 +1,54 @@
+using System;
+using System.Net.Http;
+using Grpc.Net.Client;
+
+namespace Dapr.Workflow
+{
+    internal static class GrpcKeepAlive
+    {
+        public static void Configure(WorkflowRuntimeOptions options, GrpcChannelOptions channelOptions)
+        {
+            // We check whether the environment variables are set to override
+            // the options. The environment variables ensure consistency between
+            // the different Dapr SDKs.
+            string? enableKeepAlive = Environment.GetEnvironmentVariable("DAPR_ENABLE_KEEP_ALIVE");
+            if (enableKeepAlive != null)
+            {
+                options.EnableKeepAlive = bool.Parse(enableKeepAlive);
+            }
+            string? keepAliveTime = Environment.GetEnvironmentVariable("DAPR_KEEP_ALIVE_TIME");
+            if (keepAliveTime != null)
+            {
+                options.KeepAliveTime = TimeSpan.FromSeconds(int.Parse(keepAliveTime));
+            }
+            string? keepAliveTimeout = Environment.GetEnvironmentVariable("DAPR_KEEP_ALIVE_TIMEOUT");
+            if (keepAliveTimeout != null)
+            {
+                options.KeepAliveTimeout = TimeSpan.FromSeconds(int.Parse(keepAliveTimeout));
+            }
+            string? keepAliveWithoutCalls = Environment.GetEnvironmentVariable("DAPR_KEEP_ALIVE_WITHOUT_CALLS");
+            if (keepAliveWithoutCalls != null)
+            {
+                options.KeepAliveWithoutCalls = bool.Parse(keepAliveWithoutCalls);
+            }
+            if (!options.EnableKeepAlive)
+            {
+                return;
+            }
+
+            if (channelOptions.HttpHandler is not SocketsHttpHandler socketsHandler)
+            {
+                socketsHandler = new SocketsHttpHandler();
+                channelOptions.HttpHandler = socketsHandler;
+            }
+
+            socketsHandler.KeepAlivePingDelay = options.KeepAliveTime;
+            socketsHandler.KeepAlivePingTimeout = options.KeepAliveTimeout;
+#if NET8_0_OR_GREATER
+            socketsHandler.KeepAlivePingPolicy = options.KeepAliveWithoutCalls
+                ? HttpKeepAlivePingPolicy.Always
+                : HttpKeepAlivePingPolicy.WithActiveRequests;
+#endif
+        }
+    }
+}

src/Dapr.Workflow/WorkflowRuntimeOptions.cs

@@ -146,6 +146,26 @@ internal void AddWorkflowsAndActivitiesToRegistry(DurableTaskRegistry registry)
             }
         }
 
+        /// <summary>
+        /// Enables gRPC keepalive pings on all connections.
+        /// </summary>
+        public bool EnableKeepAlive { get; set; } = false;
+
+        /// <summary>
+        /// The delay between keepalive pings. Default is 60 seconds.
+        /// </summary>
+        public TimeSpan KeepAliveTime { get; set; } = TimeSpan.FromSeconds(60);
+
+        /// <summary>
+        /// The timeout for keepalive pings. Default is 20 seconds.
+        /// </summary>
+        public TimeSpan KeepAliveTimeout { get; set; } = TimeSpan.FromSeconds(20);
+
+        /// <summary>
+        /// Whether to send keepalive pings even with no active calls. Default is true.
+        /// </summary>
+        public bool KeepAliveWithoutCalls { get; set; } = true;
+
         /// <summary>
         /// Helper class that provides a Durable Task orchestrator wrapper for a workflow.
         /// </summary>