Display warning when the agent is run in PowerShell Core

src/Agent.Listener/Agent.cs

@@ -19,6 +19,7 @@
 using Microsoft.VisualStudio.Services.Agent.Listener.Telemetry;
 using System.Collections.Generic;
 using Newtonsoft.Json;
+using Agent.Sdk.Knob;
 
 namespace Microsoft.VisualStudio.Services.Agent.Listener
 {
@@ -326,6 +327,18 @@ private async Task<int> RunAsync(AgentSettings settings, bool runOnce = false)
             try
             {
                 Trace.Info(nameof(RunAsync));
+
+                if (PlatformUtil.RunningOnWindows && AgentKnobs.CheckPsModulesLocations.GetValue(HostContext).AsBoolean())
+                {
+                    string psModulePath = Environment.GetEnvironmentVariable("PSModulePath");
+                    bool containsPwshLocations = PsModulePathUtil.ContainsPowershellCoreLocations(psModulePath);
+
+                    if (containsPwshLocations)
+                    {
+                        _term.WriteLine(StringUtil.Loc("PSModulePathLocations"));
+                    }
+                }
+
                 _listener = HostContext.GetService<IMessageListener>();
                 if (!await _listener.CreateSessionAsync(HostContext.AgentShutdownToken))
                 {

src/Agent.Sdk/Knob/AgentKnobs.cs

@@ -678,13 +678,6 @@ public class AgentKnobs
             new EnvironmentKnobSource("AGENT_KEY_USE_CNG"),
             new BuiltInDefaultKnobSource("false"));
 
-        public static readonly Knob UseInteropToFindParentProcess = new Knob(
-            nameof(UseInteropToFindParentProcess),
-            "Uses native Windows function to find parent processes of a process.",
-            new RuntimeKnobSource("AZP_AGENT_USE_INTEROP_TO_FIND_PARENT_PROCESS"),
-            new EnvironmentKnobSource("AZP_AGENT_USE_INTEROP_TO_FIND_PARENT_PROCESS"),
-            new BuiltInDefaultKnobSource("false"));
-
         public static readonly Knob RsaKeyGetConfigFromFF = new Knob(
             nameof(RsaKeyGetConfigFromFF),
             "Get config from FF.",
@@ -705,5 +698,11 @@ public class AgentKnobs
             new EnvironmentKnobSource("ROSETTA2_WARNING"),
             new PipelineFeatureSource("Rosetta2Warning"),
             new BuiltInDefaultKnobSource("false"));
+
+        public static readonly Knob CheckPsModulesLocations = new Knob(
+            nameof(CheckPsModulesLocations),
+            "Checks if the PSModulePath environment variable contains locations specific to PowerShell Core.",
+            new EnvironmentKnobSource("AZP_AGENT_CHECK_PSMODULES_LOCATIONS"),
+            new BuiltInDefaultKnobSource("false"));
     }
 }

src/Agent.Sdk/Util/PsModulePathUtil.cs

@@ -0,0 +1,38 @@
+using Microsoft.IdentityModel.Tokens;
+using System;
+using System.IO;
+using System.Linq;
+using System.Runtime.Versioning;
+
+namespace Agent.Sdk.Util
+{
+    public static class PsModulePathUtil
+    {
+        [SupportedOSPlatform("windows")]
+        public static bool ContainsPowershellCoreLocations(string psModulePath)
+        {
+            if (psModulePath.IsNullOrEmpty())
+            {
+                return false;
+            }
+
+            string programFilesPath = Environment.GetFolderPath(Environment.SpecialFolder.ProgramFiles);
+            string programFilesPath86 = Environment.GetFolderPath(Environment.SpecialFolder.ProgramFilesX86);
+
+            string psHomeModuleLocation = Path.Combine(programFilesPath, "PowerShell", "Modules");
+            string psHomeModuleLocation86 = Path.Combine(programFilesPath86, "PowerShell", "Modules");
+
+            string programFilesModuleLocation = Path.Combine(programFilesPath.ToLower(), "powershell", "7", "Modules");
+            string programFilesModuleLocation86 = Path.Combine(programFilesPath86.ToLower(), "powershell", "7", "Modules");
+
+            string[] wellKnownLocations = new[]
+            {
+                psHomeModuleLocation, psHomeModuleLocation86, programFilesModuleLocation, programFilesModuleLocation86
+            };
+
+            bool containsPwshLocations = wellKnownLocations.Any(location => psModulePath.Contains(location, StringComparison.OrdinalIgnoreCase));
+
+            return containsPwshLocations;
+        }
+    }
+}

src/Agent.Sdk/Util/WindowsProcessUtil.cs

@@ -0,0 +1,79 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+using System;
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.Linq;
+using System.Management;
+
+namespace Microsoft.VisualStudio.Services.Agent.Util
+{
+    internal record ProcessInfo(int ProcessId, string ProcessName);
+
+    public static class WindowsProcessUtil
+    {
+        internal static ProcessInfo GetParentProcessInformation(int processId)
+        {
+            using var query = new ManagementObjectSearcher($"SELECT ParentProcessId FROM Win32_Process WHERE ProcessId={processId}");
+
+            using ManagementObjectCollection queryResult = query.Get();
+
+            using ManagementObject foundProcess = queryResult.OfType<ManagementObject>().FirstOrDefault();
+
+            if (foundProcess == null)
+            {
+                return null;
+            }
+
+            int parentProcessId = (int)(uint)foundProcess["ParentProcessId"];
+
+            try
+            {
+                using var parentProcess = Process.GetProcessById(parentProcessId);
+                return new(parentProcess.Id, parentProcess.ProcessName);
+            }
+            catch (InvalidOperationException)
+            {
+                return null;
+            }
+            catch (ArgumentException)
+            {
+                return null;
+            }
+        }
+
+        internal static List<ProcessInfo> GetProcessList()
+        {
+            using var currentProcess = Process.GetCurrentProcess();
+            var currentProcessInfo = new ProcessInfo(currentProcess.Id, currentProcess.ProcessName);
+
+            var processes = new List<ProcessInfo>() { new(currentProcessInfo.ProcessId, currentProcessInfo.ProcessName) };
+
+            const int maxSearchDepthForProcess = 10;
+
+            while (processes.Count < maxSearchDepthForProcess)
+            {
+                ProcessInfo lastProcessInfo = processes.Last();
+                ProcessInfo parentProcessInfo = GetParentProcessInformation(lastProcessInfo.ProcessId);
+
+                if (parentProcessInfo == null)
+                {
+                    return processes;
+                }
+
+                processes.Add(parentProcessInfo);
+            }
+
+            return processes;
+        }
+
+        public static bool IsAgentRunningInPowerShellCore()
+        {
+            List<ProcessInfo> processList = GetProcessList();
+
+            bool isProcessRunningInPowerShellCore = processList.Exists(process => process.ProcessName == "pwsh");
+
+            return isProcessRunningInPowerShellCore;
+        }
+    }
+}