add netcoreapp3.1 C# distribtest

test/distrib/csharp/DistribTest/DistribTestDotNet.csproj

@@ -7,6 +7,7 @@
     <TargetFrameworks></TargetFrameworks>
     <TargetFrameworks Condition="'$(SKIP_NET45_DISTRIBTEST)' == ''">$(TargetFrameworks);net45</TargetFrameworks>
     <TargetFrameworks Condition="'$(SKIP_NETCOREAPP21_DISTRIBTEST)' == ''">$(TargetFrameworks);netcoreapp2.1</TargetFrameworks>
+    <TargetFrameworks Condition="'$(SKIP_NETCOREAPP31_DISTRIBTEST)' == ''">$(TargetFrameworks);netcoreapp3.1</TargetFrameworks>
     <TargetFrameworks Condition="'$(SKIP_NET50_DISTRIBTEST)' == ''">$(TargetFrameworks);net5.0</TargetFrameworks>
 
     <GenerateAssemblyCompanyAttribute>false</GenerateAssemblyCompanyAttribute>

test/distrib/csharp/run_distrib_test_dotnetcli.sh

@@ -53,6 +53,17 @@ then
   dotnet exec bin/Debug/netcoreapp2.1/publish/DistribTestDotNet.dll
 fi
 
+if [ "${SKIP_NETCOREAPP31_DISTRIBTEST}" != "1" ]
+then
+  dotnet publish -f netcoreapp3.1 DistribTestDotNet.csproj
+
+  # .NET Core target after dotnet build
+  dotnet exec bin/Debug/netcoreapp3.1/DistribTestDotNet.dll
+
+  # .NET Core target after dotnet publish
+  dotnet exec bin/Debug/netcoreapp3.1/publish/DistribTestDotNet.dll
+fi
+
 if [ "${SKIP_NET50_DISTRIBTEST}" != "1" ]
 then
   dotnet publish -f net5.0 DistribTestDotNet.csproj

tools/dockerfile/distribtest/csharp_alpine_x64/Dockerfile

@@ -26,5 +26,8 @@ RUN apk add glibc-2.30-r0.apk
 
 # installing mono on alpine is hard and we don't really need it
 ENV SKIP_NET45_DISTRIBTEST=1
+# we have a separate distribtest for netcoreapp3.1
+ENV SKIP_NETCOREAPP31_DISTRIBTEST=1
 # we have a separate distribtest for net5.0
 ENV SKIP_NET50_DISTRIBTEST=1
+

tools/dockerfile/distribtest/csharp_dotnet31_x64/Dockerfile

@@ -0,0 +1,24 @@
+# Copyright 2019 The gRPC Authors
+#
+# 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.
+
+# "3.1" tag uses debian buster
+FROM mcr.microsoft.com/dotnet/core/sdk:3.1
+
+RUN apt-get update && apt-get install -y unzip && apt-get clean
+
+# we only want to test dotnet core 3.1 runtime. This also allows us to keep
+# this docker image minimal by not installing the other runtimes.
+ENV SKIP_NET45_DISTRIBTEST=1
+ENV SKIP_NETCOREAPP21_DISTRIBTEST=1
+ENV SKIP_NET50_DISTRIBTEST=1

tools/dockerfile/distribtest/csharp_dotnet5_x64/Dockerfile

@@ -21,3 +21,4 @@ RUN apt-get update && apt-get install -y unzip && apt-get clean
 # this docker image minimal by not installing the other runtimes.
 ENV SKIP_NET45_DISTRIBTEST=1
 ENV SKIP_NETCOREAPP21_DISTRIBTEST=1
+ENV SKIP_NETCOREAPP31_DISTRIBTEST=1

tools/dockerfile/distribtest/csharp_stretch_x64/Dockerfile

@@ -40,5 +40,7 @@ RUN apt-get update && apt-get install -y unzip && apt-get clean
 RUN apt-get update && apt-get install -y curl && apt-get clean
 RUN curl https://curl.haxx.se/ca/cacert.pem > ~/cacert.pem && cert-sync ~/cacert.pem && rm -f ~/cacert.pem
 
+# we have a separate distribtest for netcoreapp3.1
+ENV SKIP_NETCOREAPP31_DISTRIBTEST=1
 # we have a separate distribtest for net5.0
 ENV SKIP_NET50_DISTRIBTEST=1

tools/dockerfile/distribtest/csharp_ubuntu1604_x64/Dockerfile

@@ -40,5 +40,7 @@ RUN apt-get update && apt-get install -y unzip && apt-get clean
 RUN apt-get update && apt-get install -y curl && apt-get clean
 RUN curl https://curl.haxx.se/ca/cacert.pem > ~/cacert.pem && cert-sync ~/cacert.pem && rm -f ~/cacert.pem
 
+# we have a separate distribtest for netcoreapp3.1
+ENV SKIP_NETCOREAPP31_DISTRIBTEST=1
 # we have a separate distribtest for net5.0
 ENV SKIP_NET50_DISTRIBTEST=1

tools/run_tests/artifacts/distribtest_targets.py

@@ -334,6 +334,7 @@ def targets():
         CSharpDistribTest('linux', 'x64', 'ubuntu1604'),
         CSharpDistribTest('linux', 'x64', 'ubuntu1604', use_dotnet_cli=True),
         CSharpDistribTest('linux', 'x64', 'alpine', use_dotnet_cli=True),
+        CSharpDistribTest('linux', 'x64', 'dotnet31', use_dotnet_cli=True),
         CSharpDistribTest('linux', 'x64', 'dotnet5', use_dotnet_cli=True),
         CSharpDistribTest('macos', 'x64'),
         CSharpDistribTest('windows', 'x86'),