feat(cli): update csharp & fsharp template to net6.0 (#23926)

Update the csharp & fsharp templates to net6.0

NET Core 3.1 is EOL, see https://endoflife.date/dotnet

Closes #23921.

----

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

CONTRIBUTING.md

@@ -60,7 +60,7 @@ The following tools need to be installed on your system prior to installing the
 - [Node.js >= 14.15.0](https://nodejs.org/download/release/latest-v14.x/)
   - We recommend using a version in [Active LTS](https://nodejs.org/en/about/releases/)
 - [Yarn >= 1.19.1, < 2](https://yarnpkg.com/lang/en/docs/install)
-- [.NET Core SDK >= 3.1.x](https://www.microsoft.com/net/download)
+- [.NET SDK >= 6.0.x](https://www.microsoft.com/net/download)
 - [Python >= 3.6.5, < 4.0](https://www.python.org/downloads/release/python-365/)
 - [Docker >= 19.03](https://docs.docker.com/get-docker/)
   - the Docker daemon must also be running

README.md

@@ -25,7 +25,7 @@ The CDK is available in the following languages:
   - We recommend using a version in [Active LTS](https://nodejs.org/en/about/releases/)
 * Python ([Python ≥ 3.6](https://www.python.org/downloads/))
 * Java ([Java ≥ 8](https://www.oracle.com/technetwork/java/javase/downloads/index.html) and [Maven ≥ 3.5.4](https://maven.apache.org/download.cgi))
-* .NET ([.NET Core ≥ 3.1](https://dotnet.microsoft.com/download))
+* .NET ([.NET ≥ 6.0](https://dotnet.microsoft.com/download))
 * Go ([Go ≥ 1.16.4](https://golang.org/))
 
 Third-party Language Deprecation: language version is only supported until its EOL (End Of Life) shared by the vendor or community and is subject to change with prior notice.

packages/aws-cdk/lib/init-templates/app/csharp/README.md

@@ -4,7 +4,7 @@ This is a blank project for CDK development with C#.
 
 The `cdk.json` file tells the CDK Toolkit how to execute your app.
 
-It uses the [.NET Core CLI](https://docs.microsoft.com/dotnet/articles/core/) to compile and execute your project.
+It uses the [.NET CLI](https://docs.microsoft.com/dotnet/articles/core/) to compile and execute your project.
 
 ## Useful commands
 

packages/aws-cdk/lib/init-templates/app/csharp/src/%name.PascalCased%/%name.PascalCased%.template.csproj

@@ -2,7 +2,7 @@
 
   <PropertyGroup>
     <OutputType>Exe</OutputType>
-    <TargetFramework>netcoreapp3.1</TargetFramework>
+    <TargetFramework>net6.0</TargetFramework>
     <!-- Roll forward to future major versions of the netcoreapp as needed -->
     <RollForward>Major</RollForward>
   </PropertyGroup>

packages/aws-cdk/lib/init-templates/app/fsharp/src/%name.PascalCased%/%name.PascalCased%.template.fsproj

@@ -2,7 +2,7 @@
 
   <PropertyGroup>
     <OutputType>Exe</OutputType>
-    <TargetFramework>netcoreapp3.1</TargetFramework>
+    <TargetFramework>net6.0</TargetFramework>
     <!-- Roll forward to future major versions of the netcoreapp as needed -->
     <RollForward>Major</RollForward>
   </PropertyGroup>

packages/aws-cdk/lib/init-templates/sample-app/csharp/README.template.md

@@ -5,7 +5,7 @@ which contains an Amazon SQS queue that is subscribed to an Amazon SNS topic.
 
 The `cdk.json` file tells the CDK Toolkit how to execute your app.
 
-It uses the [.NET Core CLI](https://docs.microsoft.com/dotnet/articles/core/) to compile and execute your project.
+It uses the [.NET CLI](https://docs.microsoft.com/dotnet/articles/core/) to compile and execute your project.
 
 ## Useful commands
 

packages/aws-cdk/lib/init-templates/sample-app/csharp/src/%name.PascalCased%/%name.PascalCased%.template.csproj

@@ -2,7 +2,7 @@
 
   <PropertyGroup>
     <OutputType>Exe</OutputType>
-    <TargetFramework>netcoreapp3.1</TargetFramework>
+    <TargetFramework>net6.0</TargetFramework>
     <!-- Roll forward to future major versions of the netcoreapp as needed -->
     <RollForward>Major</RollForward>
   </PropertyGroup>

packages/aws-cdk/lib/init-templates/sample-app/fsharp/README.template.md

@@ -6,7 +6,7 @@ which contains an Amazon SQS queue that is subscribed to an Amazon SNS topic.
 
 The `cdk.json` file tells the CDK Toolkit how to execute your app.
 
-It uses the [.NET Core CLI](https://docs.microsoft.com/dotnet/articles/core/) to compile and execute your project.
+It uses the [.NET CLI](https://docs.microsoft.com/dotnet/articles/core/) to compile and execute your project.
 
 ## Useful commands
 

packages/aws-cdk/lib/init-templates/sample-app/fsharp/src/%name.PascalCased%/%name.PascalCased%.template.fsproj

@@ -2,7 +2,7 @@
 
   <PropertyGroup>
     <OutputType>Exe</OutputType>
-    <TargetFramework>netcoreapp3.1</TargetFramework>
+    <TargetFramework>net6.0</TargetFramework>
     <!-- Roll forward to future major versions of the netcoreapp as needed -->
     <RollForward>Major</RollForward>
   </PropertyGroup>

packages/aws-cdk/test/init.test.ts

@@ -58,6 +58,7 @@ describe('constructs version', () => {
     const sln = (await fs.readFile(slnFile, 'utf8')).split(/\r?\n/);
 
     expect(csproj).toContainEqual(expect.stringMatching(/\<PackageReference Include="Constructs" Version="\[10\..*,11\..*\)"/));
+    expect(csproj).toContainEqual(expect.stringMatching(/\<TargetFramework>net6.0<\/TargetFramework>/));
     expect(sln).toContainEqual(expect.stringMatching(/\"AwsCdkTest[a-zA-Z0-9]{6}\\AwsCdkTest[a-zA-Z0-9]{6}.csproj\"/));
   });
 
@@ -73,6 +74,7 @@ describe('constructs version', () => {
     const sln = (await fs.readFile(slnFile, 'utf8')).split(/\r?\n/);
 
     expect(fsproj).toContainEqual(expect.stringMatching(/\<PackageReference Include="Constructs" Version="\[10\..*,11\..*\)"/));
+    expect(fsproj).toContainEqual(expect.stringMatching(/\<TargetFramework>net6.0<\/TargetFramework>/));
     expect(sln).toContainEqual(expect.stringMatching(/\"AwsCdkTest[a-zA-Z0-9]{6}\\AwsCdkTest[a-zA-Z0-9]{6}.fsproj\"/));
   });
 
@@ -85,6 +87,7 @@ describe('constructs version', () => {
     const csproj = (await fs.readFile(csprojFile, 'utf8')).split(/\r?\n/);
 
     expect(csproj).toContainEqual(expect.stringMatching(/\<PackageReference Include="Constructs" Version="\[10\..*,11\..*\)"/));
+    expect(csproj).toContainEqual(expect.stringMatching(/\<TargetFramework>net6.0<\/TargetFramework>/));
   });
 
   cliTestWithDirSpaces('fsharp app with spaces', async (workDir) => {
@@ -96,6 +99,7 @@ describe('constructs version', () => {
     const fsproj = (await fs.readFile(fsprojFile, 'utf8')).split(/\r?\n/);
 
     expect(fsproj).toContainEqual(expect.stringMatching(/\<PackageReference Include="Constructs" Version="\[10\..*,11\..*\)"/));
+    expect(fsproj).toContainEqual(expect.stringMatching(/\<TargetFramework>net6.0<\/TargetFramework>/));
   });
 
   cliTest('create a Python app project', async (workDir) => {

scripts/check-build-prerequisites.sh

@@ -121,13 +121,13 @@ else
     fi
 fi
 
-# [.NET == 3.1.x, == 5.x]
+# [.NET == 6.0.x]
 app="dotnet"
-app_min="3.1.0"
+app_min="6.0.100"
 check_which $app $app_min
 app_v=$(${app} --list-sdks)
 echo -e "Checking dotnet version... \c"
-if [ $(echo $app_v | grep -c -E "(3\.1\.[0-9]+|[5-7]\.[0-9]+\.[0-9]+)") -eq 1 ]
+if [ $(echo $app_v | grep -c -E "6\.[0-9]+\.[0-9]+") -eq 1 ]
 then
     echo "Ok"
 else

scripts/check-pack-prerequisites.sh

@@ -79,13 +79,13 @@ else
     wrong_version
 fi
 
-# [.NET Core SDK 3.1.*]
+# [.NET SDK 6.0.*]
 app="dotnet"
-app_min="3.1.0"
+app_min="6.0.100"
 check_which $app $app_min
 app_v=$(${app} --list-sdks)
 echo -e "Checking $app version... \c"
-if [ $(echo $app_v | grep -c -E "3\.1\.[0-9].*|[4-9]\..*") -eq 1 ]
+if [ $(echo $app_v | grep -c -E "6\.0\.[0-9].*|[4-9]\..*") -eq 1 ]
 then
     echo "Ok"
 else