Prevent attempts to select PS7 on Functions v2 (#407)

Author: AnatoliB

src/RequestProcessor.cs

@@ -39,6 +39,12 @@ internal class RequestProcessor
 
         internal RequestProcessor(MessagingStream msgStream)
         {
+            var invalidVersionMessage = FunctionsWorkerRuntimeVersionValidator.GetErrorMessage();
+            if (invalidVersionMessage != null)
+            {
+                _initTerminatingError = new InvalidOperationException(invalidVersionMessage);
+            }
+
             _msgStream = msgStream;
             _powershellPool = new PowerShellManagerPool(msgStream);
 

src/Utility/FunctionsWorkerRuntimeVersionValidator.cs

@@ -0,0 +1,37 @@
+//
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+//
+
+namespace Microsoft.Azure.Functions.PowerShellWorker.Utility
+{
+    using System;
+    using System.Text.RegularExpressions;
+
+    internal static class FunctionsWorkerRuntimeVersionValidator
+    {
+        private const string VersionVariableName = "FUNCTIONS_WORKER_RUNTIME_VERSION";
+
+        public static string GetErrorMessage()
+        {
+            var requestedVersion = Environment.GetEnvironmentVariable(VersionVariableName);
+            return GetErrorMessage(requestedVersion);
+        }
+
+        internal static string GetErrorMessage(string requestedVersion)
+        {
+            if (!string.IsNullOrWhiteSpace(requestedVersion)
+                // Assuming this code is running on Functions runtime v2, allow
+                // PowerShell version 6 only (ignoring leading and trailing spaces, and the optional ~ in front of 6)
+                && !Regex.IsMatch(requestedVersion, @"^\s*~?6\s*$"))
+            {
+                return string.Format(
+                            PowerShellWorkerStrings.InvalidFunctionsWorkerRuntimeVersion,
+                            VersionVariableName,
+                            requestedVersion);
+            }
+
+            return null;
+        }
+    }
+}

src/Worker.cs

@@ -4,10 +4,10 @@
 //
 
 using System;
+using System.Text.RegularExpressions;
 using System.Threading.Tasks;
 
 using CommandLine;
-using Microsoft.Azure.Functions.PowerShellWorker.PowerShell;
 using Microsoft.Azure.Functions.PowerShellWorker.Messaging;
 using Microsoft.Azure.Functions.PowerShellWorker.Utility;
 using Microsoft.Azure.WebJobs.Script.Grpc.Messages;
@@ -30,6 +30,8 @@ public async static Task Main(string[] args)
                 LogLevel.Information,
                 string.Format(PowerShellWorkerStrings.PowerShellWorkerVersion, typeof(Worker).Assembly.GetName().Version));
 
+            ValidateFunctionsWorkerRuntimeVersion();
+
             WorkerArguments arguments = null;
             Parser.Default.ParseArguments<WorkerArguments>(args)
                 .WithParsed(ops => arguments = ops)
@@ -47,6 +49,15 @@ public async static Task Main(string[] args)
             msgStream.Write(startedMessage);
             await requestProcessor.ProcessRequestLoop();
         }
+
+        private static void ValidateFunctionsWorkerRuntimeVersion()
+        {
+            var message = FunctionsWorkerRuntimeVersionValidator.GetErrorMessage();
+            if (message != null)
+            {
+                RpcLogger.WriteSystemLog(LogLevel.Critical, message);
+            }
+        }
     }
 
     internal class WorkerArguments

src/resources/PowerShellWorkerStrings.resx

@@ -310,4 +310,7 @@
   <data name="CommandNotFoundException_Exception" xml:space="preserve">
     <value>CommandNotFoundException detected (exception).</value>
   </data>
+  <data name="InvalidFunctionsWorkerRuntimeVersion" xml:space="preserve">
+    <value>Invalid PowerShell version specified in the {0} environment variable: {1}. This version is not supported on Azure Functions Runtime v2.</value>
+  </data>
 </root>

test/Unit/DependencyManagement/NewerDependencySnapshotDetectorTests.cs

@@ -9,7 +9,7 @@ namespace Microsoft.Azure.Functions.PowerShellWorker.Test.DependencyManagement
     using Xunit;
 
     using PowerShellWorker.DependencyManagement;
-    using Utility;
+    using PowerShellWorker.Utility;
 
     public class NewerDependencySnapshotDetectorTests
     {

test/Unit/Utility/FunctionsWorkerRuntimeVersionValidatorTests.cs

@@ -0,0 +1,43 @@
+//
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+//
+
+namespace Microsoft.Azure.Functions.PowerShellWorker.Test.Utility
+{
+    using Xunit;
+
+    using Microsoft.Azure.Functions.PowerShellWorker.Utility;
+
+    public class FunctionsWorkerRuntimeVersionValidatorTests
+    {
+        [Theory]
+        [InlineData(null)]
+        [InlineData("")]
+        [InlineData(" ")]
+        [InlineData("6")]
+        [InlineData("~6")]
+        [InlineData("  6  ")]
+        [InlineData("  ~6  ")]
+        public void NoErrorOnValidVersion(string versionToCheck)
+        {
+            Assert.Null(FunctionsWorkerRuntimeVersionValidator.GetErrorMessage(versionToCheck));
+        }
+
+        [Theory]
+        [InlineData("7")]
+        [InlineData("~7")]
+        [InlineData("  7  ")]
+        [InlineData("  ~7  ")]
+        [InlineData("5")]
+        [InlineData("8")]
+        [InlineData("~")]
+        [InlineData("anything else")]
+        public void ErrorOnInvalidVersion(string versionToCheck)
+        {
+            var error = FunctionsWorkerRuntimeVersionValidator.GetErrorMessage(versionToCheck);
+            Assert.NotNull(error);
+            Assert.Contains(versionToCheck, error);
+        }
+    }
+}