Add Python3.6 to build artifacts

tools/dockerfile/grpc_artifact_python_manylinux_x64/Dockerfile

@@ -53,6 +53,7 @@ RUN /opt/python/cp27-cp27m/bin/pip install cython
 RUN /opt/python/cp27-cp27mu/bin/pip install cython
 RUN /opt/python/cp34-cp34m/bin/pip install cython
 RUN /opt/python/cp35-cp35m/bin/pip install cython
+RUN /opt/python/cp36-cp36m/bin/pip install cython
 
 ####################################################
 # Install auditwheel with fix for namespace packages

tools/dockerfile/grpc_artifact_python_manylinux_x86/Dockerfile

@@ -53,6 +53,7 @@ RUN /opt/python/cp27-cp27m/bin/pip install cython
 RUN /opt/python/cp27-cp27mu/bin/pip install cython
 RUN /opt/python/cp34-cp34m/bin/pip install cython
 RUN /opt/python/cp35-cp35m/bin/pip install cython
+RUN /opt/python/cp36-cp36m/bin/pip install cython
 
 ####################################################
 # Install auditwheel with fix for namespace packages

tools/run_tests/artifacts/artifact_targets.py

@@ -40,7 +40,8 @@ import python_utils.jobset as jobset
 
 
 def create_docker_jobspec(name, dockerfile_dir, shell_command, environ={},
-                   flake_retries=0, timeout_retries=0, timeout_seconds=30*60):
+                   flake_retries=0, timeout_retries=0, timeout_seconds=30*60,
+                   docker_base_image=None):
   """Creates jobspec for a task running under docker."""
   environ = environ.copy()
   environ['RUN_COMMAND'] = shell_command
@@ -51,6 +52,9 @@ def create_docker_jobspec(name, dockerfile_dir, shell_command, environ={},
   docker_env = {'DOCKERFILE_DIR': dockerfile_dir,
                 'DOCKER_RUN_SCRIPT': 'tools/run_tests/dockerize/docker_run.sh',
                 'OUTPUT_DIR': 'artifacts'}
+
+  if docker_base_image is not None:
+    docker_env['DOCKER_BASE_IMAGE'] = docker_base_image
   jobspec = jobset.JobSpec(
           cmdline=['tools/run_tests/dockerize/build_and_run_docker.sh'] + docker_args,
           environ=docker_env,
@@ -116,7 +120,8 @@ class PythonArtifact:
           'tools/dockerfile/grpc_artifact_python_manylinux_%s' % self.arch,
           'tools/run_tests/artifacts/build_artifact_python.sh',
           environ=environ,
-          timeout_seconds=60*60)
+          timeout_seconds=60*60,
+          docker_base_image='quay.io/pypa/manylinux1_i686' if self.arch == 'x86' else 'quay.io/pypa/manylinux1_x86_64')
     elif self.platform == 'windows':
       if 'Python27' in self.py_version or 'Python34' in self.py_version:
         environ['EXT_COMPILER'] = 'mingw32'
@@ -336,19 +341,24 @@ def targets():
            PythonArtifact('linux', 'x86', 'cp27-cp27mu'),
            PythonArtifact('linux', 'x86', 'cp34-cp34m'),
            PythonArtifact('linux', 'x86', 'cp35-cp35m'),
+           PythonArtifact('linux', 'x86', 'cp36-cp36m'),
            PythonArtifact('linux', 'x64', 'cp27-cp27m'),
            PythonArtifact('linux', 'x64', 'cp27-cp27mu'),
            PythonArtifact('linux', 'x64', 'cp34-cp34m'),
            PythonArtifact('linux', 'x64', 'cp35-cp35m'),
+           PythonArtifact('linux', 'x64', 'cp36-cp36m'),
            PythonArtifact('macos', 'x64', 'python2.7'),
            PythonArtifact('macos', 'x64', 'python3.4'),
            PythonArtifact('macos', 'x64', 'python3.5'),
+           PythonArtifact('macos', 'x64', 'python3.6'),
            PythonArtifact('windows', 'x86', 'Python27_32bits'),
            PythonArtifact('windows', 'x86', 'Python34_32bits'),
            PythonArtifact('windows', 'x86', 'Python35_32bits'),
+           PythonArtifact('windows', 'x86', 'Python36_32bits'),
            PythonArtifact('windows', 'x64', 'Python27'),
            PythonArtifact('windows', 'x64', 'Python34'),
            PythonArtifact('windows', 'x64', 'Python35'),
+           PythonArtifact('windows', 'x64', 'Python36'),
            RubyArtifact('linux', 'x86'),
            RubyArtifact('linux', 'x64'),
            RubyArtifact('macos', 'x64'),

tools/run_tests/dockerize/build_and_run_docker.sh

@@ -42,11 +42,18 @@ cd -
 # DOCKER_RUN_SCRIPT - Script to run under docker (relative to grpc repo root)
 # OUTPUT_DIR - Directory that will be copied from inside docker after finishing.
 # DOCKERHUB_ORGANIZATION - If set, pull a prebuilt image from given dockerhub org.
+# DOCKER_BASE_IMAGE - If set, pull the latest base image.
 # $@ - Extra args to pass to docker run
 
 # Use image name based on Dockerfile location checksum
 DOCKER_IMAGE_NAME=$(basename $DOCKERFILE_DIR)_$(sha1sum $DOCKERFILE_DIR/Dockerfile | cut -f1 -d\ )
 
+# Pull the base image to force an update
+if [ "$DOCKER_BASE_IMAGE" != "" ]
+then
+  docker pull $DOCKER_BASE_IMAGE
+fi
+
 if [ "$DOCKERHUB_ORGANIZATION" != "" ]
 then
   DOCKER_IMAGE_NAME=$DOCKERHUB_ORGANIZATION/$DOCKER_IMAGE_NAME