add debian stretch distribtest

tools/dockerfile/distribtest/csharp_stretch_x64/Dockerfile

@@ -0,0 +1,41 @@
+# 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.
+
+FROM debian:stretch
+
+RUN apt-get update && apt-get install -y apt-transport-https dirmngr gnupg ca-certificates && apt-get clean
+
+RUN apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys 3FA7E0328081BFF6A14DA29AA6A19B38D3D831EF
+RUN echo "deb https://download.mono-project.com/repo/debian stable-stretch main" | tee /etc/apt/sources.list.d/mono-official-stable.list
+
+RUN apt-get update && apt-get install -y \
+    mono-devel \
+    nuget \
+    && apt-get clean
+
+RUN apt-get update && apt-get install -y curl && apt-get clean
+
+# Install dotnet SDK
+ENV DOTNET_SDK_VERSION 2.1.500
+RUN curl -sSL -o dotnet.tar.gz https://dotnetcli.blob.core.windows.net/dotnet/Sdk/$DOTNET_SDK_VERSION/dotnet-sdk-$DOTNET_SDK_VERSION-linux-x64.tar.gz \
+    && mkdir -p /usr/share/dotnet \
+    && tar -zxf dotnet.tar.gz -C /usr/share/dotnet \
+    && rm dotnet.tar.gz \
+    && ln -s /usr/share/dotnet/dotnet /usr/bin/dotnet
+
+RUN apt-get update && apt-get install -y unzip && apt-get clean
+
+# Make sure the mono certificate store is up-to-date to prevent issues with nuget restore
+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

tools/run_tests/artifacts/distribtest_targets.py

@@ -305,6 +305,8 @@ def targets():
         CppDistribTest('windows', 'x86', testcase='cmake_as_externalproject'),
         CSharpDistribTest('linux', 'x64', 'jessie'),
         CSharpDistribTest('linux', 'x86', 'jessie'),
+        CSharpDistribTest('linux', 'x64', 'stretch'),
+        CSharpDistribTest('linux', 'x64', 'stretch', use_dotnet_cli=True),
         CSharpDistribTest('linux', 'x64', 'centos7'),
         CSharpDistribTest('linux', 'x64', 'ubuntu1604'),
         CSharpDistribTest('linux', 'x64', 'ubuntu1604', use_dotnet_cli=True),