workaround the need to source activate.sh

templates/tools/dockerfile/interoptest/grpc_interop_aspnetcore/build_interop.sh.template

@@ -28,8 +28,17 @@
 
   # If needed, update dotnet SDK and put it on path
   ./build/get-dotnet.sh
-  source ./activate.sh
-
+  # Normally we would source ./activate.sh
+  # to add dotnet to PATH, but that would only
+  # work for the build and not for a subsequent
+  # dotnet run from a different shell,
+  # so we create a symlink instead.
+  # TODO(jtattermusch): Come up with a cleaner solution.
+  if [ -f $(pwd)/.dotnet/dotnet ]
+  then
+    ln -s $(pwd)/.dotnet/dotnet /usr/local/bin/dotnet
+  fi
+  
   ./build/get-grpc.sh
 
   cd testassets/InteropTestsWebsite

tools/dockerfile/interoptest/grpc_interop_aspnetcore/build_interop.sh

@@ -26,7 +26,16 @@ cd /var/local/git/grpc-dotnet
 
 # If needed, update dotnet SDK and put it on path
 ./build/get-dotnet.sh
-source ./activate.sh
+# Normally we would source ./activate.sh
+# to add dotnet to PATH, but that would only
+# work for the build and not for a subsequent
+# dotnet run from a different shell,
+# so we create a symlink instead.
+# TODO(jtattermusch): Come up with a cleaner solution.
+if [ -f $(pwd)/.dotnet/dotnet ]
+then
+  ln -s $(pwd)/.dotnet/dotnet /usr/local/bin/dotnet
+fi
 
 ./build/get-grpc.sh