[release/7.0] Do not override content root with default

src/libraries/Microsoft.Extensions.Hosting/src/HostApplicationBuilder.cs

@@ -88,7 +88,12 @@ public HostApplicationBuilder(HostApplicationBuilderSettings? settings)
 
             if (!settings.DisableDefaults)
             {
-                HostingHostBuilderExtensions.ApplyDefaultHostConfiguration(Configuration, settings.Args);
+                if (settings.ContentRootPath is null && Configuration[HostDefaults.ContentRootKey] is null)
+                {
+                    HostingHostBuilderExtensions.SetDefaultContentRoot(Configuration);
+                }
+
+                HostingHostBuilderExtensions.AddDefaultHostConfigurationSources(Configuration, settings.Args);
             }
 
             // HostApplicationBuilderSettings override all other config sources.

src/libraries/Microsoft.Extensions.Hosting/src/HostingHostBuilderExtensions.cs

@@ -198,7 +198,13 @@ public static IHostBuilder ConfigureDefaults(this IHostBuilder builder, string[]
                           .UseServiceProviderFactory(context => new DefaultServiceProviderFactory(CreateDefaultServiceProviderOptions(context)));
         }
 
-        internal static void ApplyDefaultHostConfiguration(IConfigurationBuilder hostConfigBuilder, string[]? args)
+        private static void ApplyDefaultHostConfiguration(IConfigurationBuilder hostConfigBuilder, string[]? args)
+        {
+            SetDefaultContentRoot(hostConfigBuilder);
+            AddDefaultHostConfigurationSources(hostConfigBuilder, args);
+        }
+
+        internal static void SetDefaultContentRoot(IConfigurationBuilder hostConfigBuilder)
         {
             // If we're running anywhere other than C:\Windows\system32, we default to using the CWD for the ContentRoot.
             // However, since many things like Windows services and MSIX installers have C:\Windows\system32 as there CWD which is not likely
@@ -216,7 +222,10 @@ internal static void ApplyDefaultHostConfiguration(IConfigurationBuilder hostCon
                     new KeyValuePair<string, string?>(HostDefaults.ContentRootKey, cwd),
                 });
             }
+        }
 
+        internal static void AddDefaultHostConfigurationSources(IConfigurationBuilder hostConfigBuilder, string[]? args)
+        {
             hostConfigBuilder.AddEnvironmentVariables(prefix: "DOTNET_");
             if (args is { Length: > 0 })
             {

src/libraries/Microsoft.Extensions.Hosting/src/Microsoft.Extensions.Hosting.csproj

@@ -6,6 +6,8 @@
     <EnableAOTAnalyzer>true</EnableAOTAnalyzer>
     <IsPackable>true</IsPackable>
     <PackageDescription>Hosting and startup infrastructures for applications.</PackageDescription>
+    <GeneratePackageOnBuild>true</GeneratePackageOnBuild>
+    <ServicingVersion>1</ServicingVersion>
   </PropertyGroup>
 
   <ItemGroup>

src/libraries/Microsoft.Extensions.Hosting/tests/UnitTests/HostApplicationBuilderTests.cs

@@ -229,66 +229,128 @@ public void DisableDefaultIHostEnvironmentValues()
             Assert.IsAssignableFrom<PhysicalFileProvider>(env.ContentRootFileProvider);
         }
 
-        [Fact]
-        public void ConfigurationSettingCanInfluenceEnvironment()
+        [Theory]
+        [InlineData(true)]
+        [InlineData(false)]
+        public void ConfigurationSettingCanInfluenceEnvironment(bool disableDefaults)
         {
-            using var config = new ConfigurationManager();
+            var tempPath = CreateTempSubdirectory();
 
-            config.AddInMemoryCollection(new KeyValuePair<string, string>[]
+            try
             {
-                new(HostDefaults.ApplicationKey, "AppA" ),
-                new(HostDefaults.EnvironmentKey, "EnvA" ),
-            });
+                using var config = new ConfigurationManager();
 
-            var builder = new HostApplicationBuilder(new HostApplicationBuilderSettings
-            {
-                DisableDefaults = true,
-                Configuration = config,
-            });
+                config.AddInMemoryCollection(new KeyValuePair<string, string>[]
+                {
+                    new(HostDefaults.ApplicationKey, "AppA" ),
+                    new(HostDefaults.EnvironmentKey, "EnvA" ),
+                    new(HostDefaults.ContentRootKey, tempPath)
+                });
+
+                var builder = new HostApplicationBuilder(new HostApplicationBuilderSettings
+                {
+                    DisableDefaults = disableDefaults,
+                    Configuration = config,
+                });
 
-            Assert.Equal("AppA", builder.Configuration[HostDefaults.ApplicationKey]);
-            Assert.Equal("EnvA", builder.Configuration[HostDefaults.EnvironmentKey]);
+                Assert.Equal("AppA", builder.Configuration[HostDefaults.ApplicationKey]);
+                Assert.Equal("EnvA", builder.Configuration[HostDefaults.EnvironmentKey]);
+                Assert.Equal(tempPath, builder.Configuration[HostDefaults.ContentRootKey]);
 
-            Assert.Equal("AppA", builder.Environment.ApplicationName);
-            Assert.Equal("EnvA", builder.Environment.EnvironmentName);
+                Assert.Equal("AppA", builder.Environment.ApplicationName);
+                Assert.Equal("EnvA", builder.Environment.EnvironmentName);
+                Assert.Equal(tempPath, builder.Environment.ContentRootPath);
+                var fileProviderFromBuilder = Assert.IsType<PhysicalFileProvider>(builder.Environment.ContentRootFileProvider);
+                Assert.Equal(tempPath, fileProviderFromBuilder.Root);
 
-            using IHost host = builder.Build();
+                using IHost host = builder.Build();
 
-            var hostEnvironmentFromServices = host.Services.GetRequiredService<IHostEnvironment>();
-            Assert.Equal("AppA", hostEnvironmentFromServices.ApplicationName);
-            Assert.Equal("EnvA", hostEnvironmentFromServices.EnvironmentName);
+                var hostEnvironmentFromServices = host.Services.GetRequiredService<IHostEnvironment>();
+                Assert.Equal("AppA", hostEnvironmentFromServices.ApplicationName);
+                Assert.Equal("EnvA", hostEnvironmentFromServices.EnvironmentName);
+                Assert.Equal(tempPath, hostEnvironmentFromServices.ContentRootPath);
+                var fileProviderFromServices = Assert.IsType<PhysicalFileProvider>(hostEnvironmentFromServices.ContentRootFileProvider);
+                Assert.Equal(tempPath, fileProviderFromServices.Root);
+            }
+            finally
+            {
+                Directory.Delete(tempPath);
+            }
         }
 
-        [Fact]
-        public void DirectSettingsOverrideConfigurationSetting()
+        [Theory]
+        [InlineData(true)]
+        [InlineData(false)]
+        public void DirectSettingsOverrideConfigurationSetting(bool disableDefaults)
         {
-            using var config = new ConfigurationManager();
+            var tempPath = CreateTempSubdirectory();
 
-            config.AddInMemoryCollection(new KeyValuePair<string, string>[]
+            try
             {
-                new(HostDefaults.ApplicationKey, "AppA" ),
-                new(HostDefaults.EnvironmentKey, "EnvA" ),
-            });
+                using var config = new ConfigurationManager();
 
-            var builder = new HostApplicationBuilder(new HostApplicationBuilderSettings
-            {
-                DisableDefaults = true,
-                Configuration = config,
-                ApplicationName = "AppB",
-                EnvironmentName = "EnvB",
-            });
+                config.AddInMemoryCollection(new KeyValuePair<string, string>[]
+                {
+                    new(HostDefaults.ApplicationKey, "AppA" ),
+                    new(HostDefaults.EnvironmentKey, "EnvA" ),
+                });
 
-            Assert.Equal("AppB", builder.Configuration[HostDefaults.ApplicationKey]);
-            Assert.Equal("EnvB", builder.Configuration[HostDefaults.EnvironmentKey]);
+                var builder = new HostApplicationBuilder(new HostApplicationBuilderSettings
+                {
+                    DisableDefaults = disableDefaults,
+                    Configuration = config,
+                    ApplicationName = "AppB",
+                    EnvironmentName = "EnvB",
+                    ContentRootPath = tempPath,
+                });
 
-            Assert.Equal("AppB", builder.Environment.ApplicationName);
-            Assert.Equal("EnvB", builder.Environment.EnvironmentName);
+                Assert.Equal("AppB", builder.Configuration[HostDefaults.ApplicationKey]);
+                Assert.Equal("EnvB", builder.Configuration[HostDefaults.EnvironmentKey]);
+                Assert.Equal(tempPath, builder.Configuration[HostDefaults.ContentRootKey]);
 
-            using IHost host = builder.Build();
+                Assert.Equal("AppB", builder.Environment.ApplicationName);
+                Assert.Equal("EnvB", builder.Environment.EnvironmentName);
+                Assert.Equal(tempPath, builder.Environment.ContentRootPath);
+                var fileProviderFromBuilder = Assert.IsType<PhysicalFileProvider>(builder.Environment.ContentRootFileProvider);
+                Assert.Equal(tempPath, fileProviderFromBuilder.Root);
 
-            var hostEnvironmentFromServices = host.Services.GetRequiredService<IHostEnvironment>();
-            Assert.Equal("AppB", hostEnvironmentFromServices.ApplicationName);
-            Assert.Equal("EnvB", hostEnvironmentFromServices.EnvironmentName);
+                using IHost host = builder.Build();
+
+                var hostEnvironmentFromServices = host.Services.GetRequiredService<IHostEnvironment>();
+                Assert.Equal("AppB", hostEnvironmentFromServices.ApplicationName);
+                Assert.Equal("EnvB", hostEnvironmentFromServices.EnvironmentName);
+                Assert.Equal(tempPath, hostEnvironmentFromServices.ContentRootPath);
+                var fileProviderFromServices = Assert.IsType<PhysicalFileProvider>(hostEnvironmentFromServices.ContentRootFileProvider);
+                Assert.Equal(tempPath, fileProviderFromServices.Root);
+            }
+            finally
+            {
+                Directory.Delete(tempPath);
+            }
+        }
+
+        private static string CreateTempSubdirectory()
+        {
+#if NETCOREAPP
+            DirectoryInfo directoryInfo = Directory.CreateTempSubdirectory();
+#else
+            DirectoryInfo directoryInfo = new DirectoryInfo(Path.Combine(Path.GetTempPath(), Path.GetRandomFileName()));
+            directoryInfo.Create();
+#endif
+
+            // PhysicalFileProvider will always ensure the path has a trailing slash
+            return EnsureTrailingSlash(directoryInfo.FullName);
+        }
+
+        private static string EnsureTrailingSlash(string path)
+        {
+            if (!string.IsNullOrEmpty(path) &&
+                path[path.Length - 1] != Path.DirectorySeparatorChar)
+            {
+                return path + Path.DirectorySeparatorChar;
+            }
+
+            return path;
         }
 
         [Fact]