Upgrade hello-world sample to .NET 8 (#2936)

run/helloworld/Dockerfile

@@ -1,4 +1,4 @@
-# Copyright 2022 Google Inc.
+# Copyright 2025 Google Inc.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -13,7 +13,7 @@
 # limitations under the License.
 
 # Use Microsoft's official build .NET image.
-FROM mcr.microsoft.com/dotnet/sdk:6.0 AS build-env
+FROM mcr.microsoft.com/dotnet/sdk:8.0 AS build-env
 WORKDIR /app
 
 # Copy csproj and restore as distinct layers
@@ -25,7 +25,7 @@ COPY . ./
 RUN dotnet publish -c Release -o out
 
 # Build runtime image
-FROM mcr.microsoft.com/dotnet/aspnet:6.0
+FROM mcr.microsoft.com/dotnet/aspnet:8.0
 WORKDIR /app
 COPY --from=build-env /app/out .
 

run/helloworld/Program.cs

@@ -1,4 +1,4 @@
-// Copyright 2022 Google Inc.
+// Copyright 2025 Google Inc.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.

run/helloworld/helloworld.csproj

@@ -1,9 +1,9 @@
 <Project Sdk="Microsoft.NET.Sdk.Web">
 
   <PropertyGroup>
-    <TargetFramework>net6.0</TargetFramework>
+    <TargetFramework>net8.0</TargetFramework>
     <Nullable>enable</Nullable>
     <ImplicitUsings>enable</ImplicitUsings>
   </PropertyGroup>
 
-</Project>
+</Project>

run/helloworld/runTests.ps1

@@ -0,0 +1,16 @@
+# Copyright 2025 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may not
+# use this file except in compliance with the License. You may obtain a copy of
+# the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations under
+# the License.
+
+dotnet restore --force
+dotnet publish --no-restore -c Release -f net8.0 2>&1 | %{ "$_" }