Allow using Docker actions when running within a Docker container

src/Runner.Common/Constants.cs

@@ -118,6 +118,7 @@ public static class Commands
                 //validFlags array as well present in the CommandSettings.cs
                 public static class Flags
                 {
+                    public static readonly string AllowDockerInDocker = "allow-docker-in-docker";
                     public static readonly string Commit = "commit";
                     public static readonly string Help = "help";
                     public static readonly string Replace = "replace";

src/Runner.Common/HostContext.cs

@@ -36,6 +36,7 @@ public interface IHostContext : IDisposable
         event EventHandler Unloading;
         void ShutdownRunner(ShutdownReason reason);
         void WritePerfCounter(string counter);
+        bool AllowDockerInDocker { get; set; }
     }
 
     public enum StartupType
@@ -65,6 +66,7 @@ public sealed class HostContext : EventListener, IObserver<DiagnosticListener>,
         private IDisposable _httpTraceSubscription;
         private IDisposable _diagListenerSubscription;
         private StartupType _startupType;
+        private bool _allowDockerInDocker;
         private string _perfFile;
         private RunnerWebProxy _webProxy = new RunnerWebProxy();
 
@@ -440,6 +442,18 @@ public StartupType StartupType
             }
         }
 
+        public bool AllowDockerInDocker
+        {
+            get
+            {
+                return _allowDockerInDocker;
+            }
+            set
+            {
+                _allowDockerInDocker = value;
+            }
+        }
+
         public void WritePerfCounter(string counter)
         {
             if (!string.IsNullOrEmpty(_perfFile))

src/Runner.Listener/CommandSettings.cs

@@ -27,6 +27,7 @@ public sealed class CommandSettings
 
         private readonly string[] validFlags =
         {
+            Constants.Runner.CommandLine.Flags.AllowDockerInDocker,
             Constants.Runner.CommandLine.Flags.Commit,
             Constants.Runner.CommandLine.Flags.Help,
             Constants.Runner.CommandLine.Flags.Replace,
@@ -65,6 +66,8 @@ public sealed class CommandSettings
 
         public bool RunOnce => TestFlag(Constants.Runner.CommandLine.Flags.Once);
 
+        public bool AllowDockerInDocker => TestFlag(Constants.Runner.CommandLine.Flags.AllowDockerInDocker);
+
         // Constructor.
         public CommandSettings(IHostContext context, string[] args)
         {

src/Runner.Listener/Runner.cs

@@ -192,6 +192,9 @@ public async Task<int> ExecuteCommand(CommandSettings command)
                     Trace.Info($"Set runner startup type - {startType}");
                     HostContext.StartupType = startType;
 
+                    Trace.Info($"Set runner allowDockerInDocker - {command.AllowDockerInDocker}");
+                    HostContext.AllowDockerInDocker = command.AllowDockerInDocker;
+
                     // Run the runner interactively or as service
                     return await RunAsync(settings, command.RunOnce);
                 }

src/Runner.Worker/ContainerOperationProvider.cs

@@ -25,10 +25,12 @@ public interface IContainerOperationProvider : IRunnerService
     public class ContainerOperationProvider : RunnerService, IContainerOperationProvider
     {
         private IDockerCommandManager _dockerManger;
+        private bool _allowDockerInDocker;
 
         public override void Initialize(IHostContext hostContext)
         {
             base.Initialize(hostContext);
+            _allowDockerInDocker = hostContext.AllowDockerInDocker;
             _dockerManger = HostContext.GetService<IDockerCommandManager>();
         }
 
@@ -57,13 +59,13 @@ public async Task StartContainersAsync(IExecutionContext executionContext, objec
 #if OS_WINDOWS
             // service CExecSvc is Container Execution Agent.
             ServiceController[] scServices = ServiceController.GetServices();
-            if (scServices.Any(x => String.Equals(x.ServiceName, "cexecsvc", StringComparison.OrdinalIgnoreCase) && x.Status == ServiceControllerStatus.Running))
+            if (!_allowDockerInDocker && scServices.Any(x => String.Equals(x.ServiceName, "cexecsvc", StringComparison.OrdinalIgnoreCase) && x.Status == ServiceControllerStatus.Running))
             {
                 throw new NotSupportedException("Container feature is not supported when runner is already running inside container.");
             }
 #else
             var initProcessCgroup = File.ReadLines("/proc/1/cgroup");
-            if (initProcessCgroup.Any(x => x.IndexOf(":/docker/", StringComparison.OrdinalIgnoreCase) >= 0))
+            if (!_allowDockerInDocker && initProcessCgroup.Any(x => x.IndexOf(":/docker/", StringComparison.OrdinalIgnoreCase) >= 0))
             {
                 throw new NotSupportedException("Container feature is not supported when runner is already running inside container.");
             }

src/Test/L0/TestHostContext.cs

@@ -29,6 +29,7 @@ public sealed class TestHostContext : IHostContext, IDisposable
         private AssemblyLoadContext _loadContext;
         private string _tempDirectoryRoot = Path.Combine(Path.GetTempPath(), Guid.NewGuid().ToString("D"));
         private StartupType _startupType;
+        private bool _allowDockerInDocker;
         public event EventHandler Unloading;
         public CancellationToken RunnerShutdownToken => _runnerShutdownTokenSource.Token;
         public ShutdownReason RunnerShutdownReason { get; private set; }
@@ -86,6 +87,18 @@ public StartupType StartupType
             }
         }
 
+        public bool AllowDockerInDocker
+        {
+            get
+            {
+                return _allowDockerInDocker;
+            }
+            set
+            {
+                _allowDockerInDocker = value;
+            }
+        }
+
         public ProductInfoHeaderValue UserAgent => new ProductInfoHeaderValue("L0Test", "0.0");
 
         public RunnerWebProxy WebProxy => new RunnerWebProxy();