Use MSBuild project extensions instead of importing the users project

Implicit imports prevents using <Import> on a project file that has the Sdk attribute. This change instead generates a file in the MSBuildProjectExtensionsPath to inject targets require to find the UserSecretsId property in a project.

Resolves #242

Author: Nate McMaster

src/Microsoft.Extensions.SecretManager.Tools/Internal/ProjectIdResolver.cs

@@ -5,19 +5,16 @@
 using System.Collections.Generic;
 using System.Diagnostics;
 using System.IO;
-using System.Linq;
 using System.Reflection;
 using Microsoft.Extensions.Tools.Internal;
 
 namespace Microsoft.Extensions.SecretManager.Tools.Internal
 {
-    public class ProjectIdResolver : IDisposable
+    public class ProjectIdResolver
     {
-        private const string TargetsFileName = "FindUserSecretsProperty.targets";
         private const string DefaultConfig = "Debug";
         private readonly IReporter _reporter;
         private readonly string _workingDirectory;
-        private readonly List<string> _tempFiles = new List<string>();
 
         public ProjectIdResolver(IReporter reporter, string workingDirectory)
         {
@@ -29,83 +26,82 @@ public string Resolve(string project, string configuration)
         {
             var finder = new MsBuildProjectFinder(_workingDirectory);
             var projectFile = finder.FindMsBuildProject(project);
+            EnsureProjectExtensionTargetsExist(projectFile);
 
             _reporter.Verbose(Resources.FormatMessage_Project_File_Path(projectFile));
 
-            var targetFile = GetTargetFile();
-            var outputFile = Path.GetTempFileName();
-            _tempFiles.Add(outputFile);
-
             configuration = !string.IsNullOrEmpty(configuration)
                 ? configuration
                 : DefaultConfig;
 
-            var args = new[]
-            {
-                "msbuild",
-                targetFile,
-                "/nologo",
-                "/t:_FindUserSecretsProperty",
-                $"/p:Project={projectFile}",
-                $"/p:OutputFile={outputFile}",
-                $"/p:Configuration={configuration}"
-            };
-            var psi = new ProcessStartInfo
+            var outputFile = Path.GetTempFileName();
+            try
             {
-                FileName = DotNetMuxer.MuxerPathOrDefault(),
-                Arguments = ArgumentEscaper.EscapeAndConcatenate(args),
-                RedirectStandardOutput = true,
-                RedirectStandardError = true
-            };
+                var args = new[]
+                {
+                    "msbuild",
+                    projectFile,
+                    "/nologo",
+                    "/t:_ExtractUserSecretsMetadata", // defined in ProjectIdResolverTargets.xml
+                    $"/p:_UserSecretsMetadataFile={outputFile}",
+                    $"/p:Configuration={configuration}"
+                };
+                var psi = new ProcessStartInfo
+                {
+                    FileName = DotNetMuxer.MuxerPathOrDefault(),
+                    Arguments = ArgumentEscaper.EscapeAndConcatenate(args),
+                    RedirectStandardOutput = true,
+                    RedirectStandardError = true
+                };
 
 #if DEBUG
-            _reporter.Verbose($"Invoking '{psi.FileName} {psi.Arguments}'");
+                _reporter.Verbose($"Invoking '{psi.FileName} {psi.Arguments}'");
 #endif
 
-            var process = Process.Start(psi);
-            process.WaitForExit();
+                var process = Process.Start(psi);
+                process.WaitForExit();
 
-            if (process.ExitCode != 0)
-            {
-                _reporter.Verbose(process.StandardOutput.ReadToEnd());
-                _reporter.Verbose(process.StandardError.ReadToEnd());
-                throw new InvalidOperationException(Resources.FormatError_ProjectFailedToLoad(projectFile));
-            }
-
-            var id = File.ReadAllText(outputFile)?.Trim();
-            if (string.IsNullOrEmpty(id))
-            {
-                throw new InvalidOperationException(Resources.FormatError_ProjectMissingId(projectFile));
-            }
-
-            return id;
-        }
+                if (process.ExitCode != 0)
+                {
+                    _reporter.Verbose(process.StandardOutput.ReadToEnd());
+                    _reporter.Verbose(process.StandardError.ReadToEnd());
+                    throw new InvalidOperationException(Resources.FormatError_ProjectFailedToLoad(projectFile));
+                }
 
-        private string GetTargetFile()
-        {
-            var assemblyDir = Path.GetDirectoryName(GetType().GetTypeInfo().Assembly.Location);
+                var id = File.ReadAllText(outputFile)?.Trim();
+                if (string.IsNullOrEmpty(id))
+                {
+                    throw new InvalidOperationException(Resources.FormatError_ProjectMissingId(projectFile));
+                }
+                return id;
 
-            // targets should be in one of these locations, depending on test setup and tools installation
-            var searchPaths = new[]
+            }
+            finally
             {
-                AppContext.BaseDirectory,
-                assemblyDir, // next to assembly
-                Path.Combine(assemblyDir, "../../toolassets"), // inside the nupkg
-                Path.Combine(assemblyDir, "toolassets"), // for local builds
-                Path.Combine(AppContext.BaseDirectory, "../../toolassets"), // relative to packaged deps.json
-            };
-
-            return searchPaths
-                .Select(dir => Path.Combine(dir, TargetsFileName))
-                .Where(File.Exists)
-                .First();
+                TryDelete(outputFile);
+            }
         }
 
-        public void Dispose()
+        private void EnsureProjectExtensionTargetsExist(string projectFile)
         {
-            foreach (var file in _tempFiles)
+            // relies on MSBuildProjectExtensionsPath and Microsoft.Common.targets to import this file
+            // into the target project
+            var projectExtensionsPath = Path.Combine(
+                Path.GetDirectoryName(projectFile),
+                "obj",
+                $"{Path.GetFileName(projectFile)}.usersecrets.targets");
+
+            Directory.CreateDirectory(Path.GetDirectoryName(projectExtensionsPath));
+
+            // should overwrite the file always. Hypothetically, another version of the user-secrets tool
+            // could have already put a file here. We want to ensure the target file matches the currently
+            // running tool
+            using (var resource = GetType().GetTypeInfo().Assembly.GetManifestResourceStream("ProjectIdResolverTargets.xml"))
+            using (var stream = new FileStream(projectExtensionsPath, FileMode.Create))
+            using (var writer = new StreamWriter(stream))
             {
-                TryDelete(file);
+                writer.WriteLine("<!-- Auto-generated by dotnet-user-secrets. This file can be deleted and should not be commited to source control. -->");
+                resource.CopyTo(stream);
             }
         }
 

src/Microsoft.Extensions.SecretManager.Tools/Microsoft.Extensions.SecretManager.Tools.nuspec

@@ -23,7 +23,6 @@
   </metadata>
   <files>
     <file src="prefercliruntime" target="\prefercliruntime" />
-    <file src="toolassets\FindUserSecretsProperty.targets" target="toolassets\" />
     <file src="dotnet-user-secrets.dll" target="lib\netcoreapp1.0\" />
     <file src="dotnet-user-secrets.deps.json" target="lib\netcoreapp1.0\" />
     <file src="dotnet-user-secrets.runtimeconfig.json" target="lib\netcoreapp1.0\" />

src/Microsoft.Extensions.SecretManager.Tools/Program.cs

@@ -124,10 +124,8 @@ internal string ResolveId(CommandLineOptions options, IReporter reporter)
                 return options.Id;
             }
 
-            using (var resolver = new ProjectIdResolver(reporter, _workingDirectory))
-            {
-                return resolver.Resolve(options.Project, options.Configuration);
-            }
+            var resolver = new ProjectIdResolver(reporter, _workingDirectory);
+            return resolver.Resolve(options.Project, options.Configuration);
         }
     }
 }

src/Microsoft.Extensions.SecretManager.Tools/project.json

@@ -5,16 +5,17 @@
     "emitEntryPoint": true,
     "warningsAsErrors": true,
     "keyFile": "../../tools/Key.snk",
-    "copyToOutput": "toolassets/*.targets",
+    "embed": {
+      "mappings": {
+        "ProjectIdResolverTargets.xml": "./resources/ProjectIdResolverTargets.xml"
+      }
+    },
     "compile": {
       "include": "../Shared/**/*.cs"
     }
   },
   "publishOptions": {
-    "include": [
-      "toolassets/*.targets",
-      "prefercliruntime"
-    ]
+    "include": "prefercliruntime"
   },
   "dependencies": {
     "Microsoft.Extensions.Configuration.UserSecrets": "1.0.0",

src/Microsoft.Extensions.SecretManager.Tools/resources/ProjectIdResolverTargets.xml

@@ -0,0 +1,5 @@
+<Project>
+    <Target Name="_ExtractUserSecretsMetadata">
+        <WriteLinesToFile File="$(_UserSecretsMetadataFile)" Lines="$(UserSecretsId)" />
+    </Target>
+</Project>

src/Microsoft.Extensions.SecretManager.Tools/toolassets/FindUserSecretsProperty.targets

@@ -32,9 +32,7 @@ public string GetTempSecretProject()
             return GetTempSecretProject(out userSecretsId);
         }
 
-        private const string ProjectTemplate = @"<Project ToolsVersion=""14.0"" xmlns=""http://schemas.microsoft.com/developer/msbuild/2003"">
-  <Import Project=""$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props"" />
-
+        private const string ProjectTemplate = @"<Project ToolsVersion=""15.0"" Sdk=""Microsoft.NET.Sdk"">
   <PropertyGroup>
     <OutputType>Exe</OutputType>
     <TargetFrameworks>netcoreapp1.0</TargetFrameworks>
@@ -43,12 +41,8 @@ public string GetTempSecretProject()
 
   <ItemGroup>
     <Compile Include=""**\*.cs"" Exclude=""Excluded.cs"" />
-
-    <PackageReference Include=""Microsoft.NET.Sdk"" Version=""1.0.0-*"" PrivateAssets=""All"" />
     <PackageReference Include=""Microsoft.NETCore.App"" Version=""1.0.1"" />
   </ItemGroup>
-
-  <Import Project=""$(MSBuildToolsPath)\Microsoft.CSharp.targets"" />
 </Project>";
 
         public string GetTempSecretProject(out string userSecretsId)