New mode that allows you to disable all external message listeners. Closes GH-2007

Author: jeremydmiller

docs/guide/messaging/listeners.md

@@ -162,5 +162,15 @@ This option does a couple things:
 * Sets any local execution of the listener's internal, local queue to be strictly sequential and only process messages with
   a single thread
 
+## Disabling All External Listeners
 
+In some cases, you may want to disable all message processing for messages received from external
+transports like Rabbit MQ or AWS SQS. To do that, simply set:
+
+snippet: sample_disable_all_listeners
+
+The original use case for this flag was a command line tool that needed to publish messages to
+a system through Rabbit MQ then exit. Having that process also trying to publish messages received
+from Rabbit MQ kept the command line tool from quitting quickly as Wolverine had to "drain" ongoing
+work. For that kind of tool, we recommend this setting.
 

src/Testing/CoreTests/WolverineOptionsTests.cs

@@ -27,6 +27,12 @@ public void publish_agent_events_should_be_false_by_default()
         new WolverineOptions().Policies.PublishAgentEvents.ShouldBeFalse();
     }
 
+    [Fact]
+    public void do_not_disable_external_listeners_by_default()
+    {
+        new WolverineOptions().DisableAllExternalListeners.ShouldBeFalse();
+    }
+
     [Fact]
     public void default_dead_letter_queue_behavior_is_discard()
     {

src/Transports/RabbitMQ/Wolverine.RabbitMQ.Tests/disable_external_listeners.cs

@@ -0,0 +1,37 @@
+using Microsoft.Extensions.Hosting;
+using Shouldly;
+using Wolverine.ComplianceTests;
+using Wolverine.Tracking;
+using Xunit;
+
+namespace Wolverine.RabbitMQ.Tests;
+
+public class disable_external_listeners
+{
+    [Fact]
+    public async Task listeners_are_not_active()
+    {
+        using var host = await Host.CreateDefaultBuilder()
+
+            #region sample_disable_all_listeners
+
+            .UseWolverine(opts =>
+            {
+                // This will disable all message listening to
+                // external message brokers
+                opts.DisableAllExternalListeners = true;
+                
+                opts.DisableConventionalDiscovery();
+
+                // This could never, ever work
+                opts.UseRabbitMq().AutoProvision();
+                opts.ListenToRabbitQueue("incoming");
+            }).StartAsync();
+
+        #endregion
+
+        var activeListeners = host.GetRuntime().Endpoints.ActiveListeners().ToArray();
+        activeListeners
+            .Any().ShouldBeFalse();
+    }
+}

src/Wolverine/Configuration/EndpointCollection.cs

@@ -237,6 +237,8 @@ public IReadOnlyList<Endpoint> LeaderPinnedListeners()
 
     public async Task StartListenersAsync()
     {
+        if (_options.DisableAllExternalListeners) return;
+        
         var listeningEndpoints = _options.Transports.SelectMany(x => x.Endpoints())
             .Where(x => x is not LocalQueue)
             .Where(x => x.ShouldAutoStartAsListener(_options.Durability));

src/Wolverine/WolverineOptions.cs

@@ -294,6 +294,13 @@ public AutoCreate AutoBuildMessageStorageOnStartup
     ///     to latch all outgoing message sending
     /// </summary>
     internal bool ExternalTransportsAreStubbed { get; set; }
+    
+    /// <summary>
+    /// Should all listeners for external transports be disabled in
+    /// this process? You may want to use this for command line applications
+    /// that publish outbound messages
+    /// </summary>
+    public bool DisableAllExternalListeners { get; set; }
 
     [IgnoreDescription]
     internal LocalTransport LocalRouting => Transports.GetOrCreate<LocalTransport>();