feat: Add TC host strategy

src/Testcontainers.Keycloak/KeycloakContainer.cs

@@ -4,8 +4,6 @@ namespace Testcontainers.Keycloak;
 [PublicAPI]
 public sealed class KeycloakContainer : DockerContainer
 {
-    private readonly KeycloakConfiguration _configuration;
-
     /// <summary>
     /// Initializes a new instance of the <see cref="KeycloakContainer" /> class.
     /// </summary>
@@ -14,7 +12,6 @@ public sealed class KeycloakContainer : DockerContainer
     public KeycloakContainer(KeycloakConfiguration configuration, ILogger logger)
         : base(configuration, logger)
     {
-        _configuration = configuration;
     }
 
     /// <summary>

src/Testcontainers/Builders/TestcontainersCloudEndpointAuthenticationProvider.cs

@@ -0,0 +1,155 @@
+namespace DotNet.Testcontainers.Builders
+{
+  using System;
+  using System.Text.Json;
+  using DotNet.Testcontainers.Configurations;
+  using DotNet.Testcontainers.Images;
+  using JetBrains.Annotations;
+
+  /// <summary>
+  /// When configuring the endpoint for a container runtime, the `DOCKER_HOST`
+  /// environment variable is commonly used. This approach can become messy due to
+  /// the variety of alternative container runtimes. Even though Testcontainers logs
+  /// the container runtime that is being used, developers find it difficult to
+  /// determine which runtime is driving the tests on their environment. If multiple
+  /// container runtimes are present in a development environment, we prioritize
+  /// Testcontainers Cloud if it is running.
+  /// </summary>
+  [PublicAPI]
+  internal sealed class TestcontainersHostEndpointAuthenticationProvider : DockerEndpointAuthenticationProvider, ICustomConfiguration
+  {
+    private readonly ICustomConfiguration _customConfiguration;
+
+    private readonly Uri _dockerEngine;
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="TestcontainersHostEndpointAuthenticationProvider" /> class.
+    /// </summary>
+    public TestcontainersHostEndpointAuthenticationProvider()
+    {
+      _customConfiguration = new TestcontainersHostConfiguration();
+      _dockerEngine = GetDockerHost();
+    }
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="TestcontainersHostEndpointAuthenticationProvider" /> class.
+    /// </summary>
+    /// <param name="lines">A list of Java properties file lines.</param>
+    public TestcontainersHostEndpointAuthenticationProvider(params string[] lines)
+    {
+      _customConfiguration = new TestcontainersHostConfiguration(lines);
+      _dockerEngine = GetDockerHost();
+    }
+
+    /// <inheritdoc />
+    public override bool IsApplicable()
+    {
+      return _dockerEngine != null && "tcp".Equals(_dockerEngine.Scheme, StringComparison.OrdinalIgnoreCase);
+    }
+
+    /// <inheritdoc />
+    public override IDockerEndpointAuthenticationConfiguration GetAuthConfig()
+    {
+      return new DockerEndpointAuthenticationConfiguration(_dockerEngine);
+    }
+
+    /// <inheritdoc />
+    public string GetDockerConfig()
+    {
+      return _customConfiguration.GetDockerConfig();
+    }
+
+    /// <inheritdoc />
+    public Uri GetDockerHost()
+    {
+      return _customConfiguration.GetDockerHost();
+    }
+
+    /// <inheritdoc />
+    public string GetDockerHostOverride()
+    {
+      return _customConfiguration.GetDockerHostOverride();
+    }
+
+    /// <inheritdoc />
+    public string GetDockerSocketOverride()
+    {
+      return _customConfiguration.GetDockerSocketOverride();
+    }
+
+    /// <inheritdoc />
+    public JsonDocument GetDockerAuthConfig()
+    {
+      return _customConfiguration.GetDockerAuthConfig();
+    }
+
+    /// <inheritdoc />
+    public string GetDockerCertPath()
+    {
+      return _customConfiguration.GetDockerCertPath();
+    }
+
+    /// <inheritdoc />
+    public bool GetDockerTls()
+    {
+      return _customConfiguration.GetDockerTls();
+    }
+
+    /// <inheritdoc />
+    public bool GetDockerTlsVerify()
+    {
+      return _customConfiguration.GetDockerTlsVerify();
+    }
+
+    /// <inheritdoc />
+    public bool GetRyukDisabled()
+    {
+      return _customConfiguration.GetRyukDisabled();
+    }
+
+    /// <inheritdoc />
+    public bool GetRyukContainerPrivileged()
+    {
+      return _customConfiguration.GetRyukContainerPrivileged();
+    }
+
+    /// <inheritdoc />
+    public IImage GetRyukContainerImage()
+    {
+      return _customConfiguration.GetRyukContainerImage();
+    }
+
+    /// <inheritdoc />
+    public string GetHubImageNamePrefix()
+    {
+      return _customConfiguration.GetHubImageNamePrefix();
+    }
+
+    private sealed class TestcontainersHostConfiguration : PropertiesFileConfiguration
+    {
+      public TestcontainersHostConfiguration()
+      {
+      }
+
+      public TestcontainersHostConfiguration(params string[] lines)
+        : base(lines)
+      {
+      }
+
+      protected override Uri GetDockerHost(string propertyName)
+      {
+        return base.GetDockerHost("tc.host");
+      }
+
+      protected override string GetDockerHostOverride(string propertyName)
+      {
+        return null;
+      }
+
+      protected override string GetDockerSocketOverride(string propertyName)
+      {
+        return null;
+      }
+    }
+  }
+}

src/Testcontainers/Configurations/CustomConfiguration.cs

@@ -14,27 +14,27 @@ protected CustomConfiguration(IReadOnlyDictionary<string, string> properties)
       _properties = properties;
     }
 
-    protected string GetDockerConfig(string propertyName)
+    protected virtual string GetDockerConfig(string propertyName)
     {
       return GetPropertyValue<string>(propertyName);
     }
 
-    protected Uri GetDockerHost(string propertyName)
+    protected virtual Uri GetDockerHost(string propertyName)
     {
       return _properties.TryGetValue(propertyName, out var propertyValue) && Uri.TryCreate(propertyValue, UriKind.RelativeOrAbsolute, out var dockerHost) ? dockerHost : null;
     }
 
-    protected string GetDockerHostOverride(string propertyName)
+    protected virtual string GetDockerHostOverride(string propertyName)
     {
       return GetPropertyValue<string>(propertyName);
     }
 
-    protected string GetDockerSocketOverride(string propertyName)
+    protected virtual string GetDockerSocketOverride(string propertyName)
     {
       return GetPropertyValue<string>(propertyName);
     }
 
-    protected JsonDocument GetDockerAuthConfig(string propertyName)
+    protected virtual JsonDocument GetDockerAuthConfig(string propertyName)
     {
       _ = _properties.TryGetValue(propertyName, out var propertyValue);
 
@@ -53,32 +53,32 @@ protected JsonDocument GetDockerAuthConfig(string propertyName)
       }
     }
 
-    protected string GetDockerCertPath(string propertyName)
+    protected virtual string GetDockerCertPath(string propertyName)
     {
       return GetPropertyValue<string>(propertyName);
     }
 
-    protected bool GetDockerTls(string propertyName)
+    protected virtual bool GetDockerTls(string propertyName)
     {
       return GetPropertyValue<bool>(propertyName);
     }
 
-    protected bool GetDockerTlsVerify(string propertyName)
+    protected virtual bool GetDockerTlsVerify(string propertyName)
     {
       return GetPropertyValue<bool>(propertyName);
     }
 
-    protected bool GetRyukDisabled(string propertyName)
+    protected virtual bool GetRyukDisabled(string propertyName)
     {
       return GetPropertyValue<bool>(propertyName);
     }
 
-    protected bool GetRyukContainerPrivileged(string propertyName)
+    protected virtual bool GetRyukContainerPrivileged(string propertyName)
     {
       return GetPropertyValue<bool>(propertyName);
     }
 
-    protected IImage GetRyukContainerImage(string propertyName)
+    protected virtual IImage GetRyukContainerImage(string propertyName)
     {
       _ = _properties.TryGetValue(propertyName, out var propertyValue);
 
@@ -97,7 +97,7 @@ protected IImage GetRyukContainerImage(string propertyName)
       }
     }
 
-    protected string GetHubImageNamePrefix(string propertyName)
+    protected virtual string GetHubImageNamePrefix(string propertyName)
     {
       return GetPropertyValue<string>(propertyName);
     }

src/Testcontainers/Configurations/EnvironmentConfiguration.cs

@@ -8,7 +8,7 @@ namespace DotNet.Testcontainers.Configurations
   /// <summary>
   /// Reads and maps the custom configurations from the environment variables.
   /// </summary>
-  internal sealed class EnvironmentConfiguration : CustomConfiguration, ICustomConfiguration
+  internal class EnvironmentConfiguration : CustomConfiguration, ICustomConfiguration
   {
     private const string DockerConfig = "DOCKER_CONFIG";
 

src/Testcontainers/Configurations/PropertiesFileConfiguration.cs

@@ -9,7 +9,7 @@ namespace DotNet.Testcontainers.Configurations
   /// <summary>
   /// Reads and maps the custom configurations from the Testcontainers properties file.
   /// </summary>
-  internal sealed class PropertiesFileConfiguration : CustomConfiguration, ICustomConfiguration
+  internal class PropertiesFileConfiguration : CustomConfiguration, ICustomConfiguration
   {
     static PropertiesFileConfiguration()
     {

src/Testcontainers/Configurations/TestcontainersSettings.cs

@@ -21,9 +21,11 @@ public static class TestcontainersSettings
   {
     private static readonly ManualResetEventSlim ManualResetEvent = new ManualResetEventSlim(false);
 
-    private static readonly IDockerEndpointAuthenticationConfiguration DockerEndpointAuthConfig =
+    [CanBeNull]
+    private static readonly IDockerEndpointAuthenticationProvider DockerEndpointAuthProvider =
       new IDockerEndpointAuthenticationProvider[]
         {
+          new TestcontainersHostEndpointAuthenticationProvider(),
           new MTlsEndpointAuthenticationProvider(),
           new TlsEndpointAuthenticationProvider(),
           new EnvironmentEndpointAuthenticationProvider(),
@@ -32,9 +34,11 @@ public static class TestcontainersSettings
           new RootlessUnixEndpointAuthenticationProvider(),
         }
         .Where(authProvider => authProvider.IsApplicable())
-        .Where(authProvider => authProvider.IsAvailable())
-        .Select(authProvider => authProvider.GetAuthConfig())
-        .FirstOrDefault();
+        .FirstOrDefault(authProvider => authProvider.IsAvailable());
+
+    [CanBeNull]
+    private static readonly IDockerEndpointAuthenticationConfiguration DockerEndpointAuthConfig =
+      DockerEndpointAuthProvider?.GetAuthConfig();
 
     static TestcontainersSettings()
     {
@@ -103,14 +107,16 @@ static TestcontainersSettings()
     /// </summary>
     [CanBeNull]
     public static string DockerHostOverride { get; set; }
-      = PropertiesFileConfiguration.Instance.GetDockerHostOverride() ?? EnvironmentConfiguration.Instance.GetDockerHostOverride();
+      = DockerEndpointAuthProvider is ICustomConfiguration config
+        ? config.GetDockerHostOverride() : PropertiesFileConfiguration.Instance.GetDockerHostOverride() ?? EnvironmentConfiguration.Instance.GetDockerHostOverride();
 
     /// <summary>
     /// Gets or sets the Docker socket override value.
     /// </summary>
     [CanBeNull]
     public static string DockerSocketOverride { get; set; }
-      = PropertiesFileConfiguration.Instance.GetDockerSocketOverride() ?? EnvironmentConfiguration.Instance.GetDockerSocketOverride();
+      = DockerEndpointAuthProvider is ICustomConfiguration config
+        ? config.GetDockerSocketOverride() : PropertiesFileConfiguration.Instance.GetDockerSocketOverride() ?? EnvironmentConfiguration.Instance.GetDockerSocketOverride();
 
     /// <summary>
     /// Gets or sets a value indicating whether the <see cref="ResourceReaper" /> is enabled or not.

tests/Testcontainers.Tests/Fixtures/Images/HealthCheckFixture.cs

@@ -3,7 +3,6 @@ namespace DotNet.Testcontainers.Tests.Fixtures
   using System.IO;
   using System.Threading.Tasks;
   using DotNet.Testcontainers.Builders;
-  using DotNet.Testcontainers.Containers;
   using DotNet.Testcontainers.Images;
   using JetBrains.Annotations;
   using Xunit;

tests/Testcontainers.Tests/Unit/Configurations/DockerEndpointAuthenticationProviderTest.cs

@@ -46,13 +46,30 @@ internal void AuthConfigShouldGetDockerClientEndpoint(IDockerEndpointAuthenticat
       }
     }
 
+    public sealed class TestcontainersHostEndpointAuthenticationProviderTest
+    {
+      [Fact]
+      public void GetDockerHostOverrideReturnsNull()
+      {
+        ICustomConfiguration customConfiguration = new TestcontainersHostEndpointAuthenticationProvider("host.override=host.docker.internal");
+        Assert.Null(customConfiguration.GetDockerHostOverride());
+      }
+
+      [Fact]
+      public void GetDockerSocketOverrideReturnsNull()
+      {
+        ICustomConfiguration customConfiguration = new TestcontainersHostEndpointAuthenticationProvider("docker.socket.override=/var/run/docker.sock");
+        Assert.Null(customConfiguration.GetDockerSocketOverride());
+      }
+    }
+
     private sealed class AuthProviderTestData : List<object[]>
     {
       public AuthProviderTestData()
       {
         var defaultConfiguration = new PropertiesFileConfiguration(Array.Empty<string>());
-        var dockerTlsConfiguration = new PropertiesFileConfiguration("docker.tls=true", $"docker.cert.path={CertificatesDirectoryPath}");
-        var dockerMTlsConfiguration = new PropertiesFileConfiguration("docker.tls.verify=true", $"docker.cert.path={CertificatesDirectoryPath}");
+        var dockerTlsConfiguration = new PropertiesFileConfiguration("docker.tls=true", "docker.cert.path=" + CertificatesDirectoryPath);
+        var dockerMTlsConfiguration = new PropertiesFileConfiguration("docker.tls.verify=true", "docker.cert.path=" + CertificatesDirectoryPath);
         Add(new object[] { new MTlsEndpointAuthenticationProvider(defaultConfiguration), false });
         Add(new object[] { new MTlsEndpointAuthenticationProvider(dockerMTlsConfiguration), true });
         Add(new object[] { new MTlsEndpointAuthenticationProvider(Array.Empty<ICustomConfiguration>()), false });
@@ -67,6 +84,8 @@ public AuthProviderTestData()
         Add(new object[] { new EnvironmentEndpointAuthenticationProvider(defaultConfiguration, DockerHostConfiguration), true });
         Add(new object[] { new NpipeEndpointAuthenticationProvider(), RuntimeInformation.IsOSPlatform(OSPlatform.Windows) });
         Add(new object[] { new UnixEndpointAuthenticationProvider(), !RuntimeInformation.IsOSPlatform(OSPlatform.Windows) });
+        Add(new object[] { new TestcontainersHostEndpointAuthenticationProvider(string.Empty), false });
+        Add(new object[] { new TestcontainersHostEndpointAuthenticationProvider("tc.host=" + DockerHost), true });
       }
     }
 
@@ -78,6 +97,7 @@ public AuthConfigTestData()
         Add(new object[] { new EnvironmentEndpointAuthenticationProvider(DockerHostConfiguration).GetAuthConfig(), new Uri(DockerHost) });
         Add(new object[] { new NpipeEndpointAuthenticationProvider().GetAuthConfig(), new Uri("npipe://./pipe/docker_engine") });
         Add(new object[] { new UnixEndpointAuthenticationProvider().GetAuthConfig(), new Uri("unix:///var/run/docker.sock") });
+        Add(new object[] { new TestcontainersHostEndpointAuthenticationProvider("tc.host=" + DockerHost).GetAuthConfig(), new Uri(DockerHost) });
       }
     }
   }