Automate release process using CircleCI (#320)

Author: liyanhui1228

.circleci/config.yml

@@ -38,3 +38,12 @@ jobs:
           name: Run tests - opencensus
           command: |
             nox -f nox.py
+      - deploy:
+          name: Push to PyPI (if this is a release tag).
+          command: scripts/twine_upload.sh
+
+deployment:
+  tag_build_for_cci2:
+    tag: /(([a-z]+)-)*([0-9]+)\.([0-9]+)\.([0-9]+)/
+    commands:
+      - true

RELEASING.md

@@ -2,20 +2,10 @@
 
 ## Steps
 
-### Create a Github release
-
 ### Update the version number in `setup.py`
 
 ### Update the version number in `stackdriver_exporter.py`
 
-### Build the Python wheel
-
-```
-python setup.py bdist_wheel
-```
-
-### Upload the package to PyPI using twine
+### Create a Github release
 
-```
-twine upload dist/*
-```
+Then the Circle CI will build the package and upload it to PyPI automatically.

scripts/twine_upload.sh

@@ -0,0 +1,32 @@
+# Copyright 2018, OpenCensus 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.
+
+set -ev
+
+# If this is not a CircleCI tag, no-op.
+if [[ -z "$CIRCLE_TAG" ]]; then
+  echo "This is not a release tag. Doing nothing."
+  exit 0
+fi
+
+echo -e "[pypi]" >> ~/.pypirc
+echo -e "username = $PYPI_USERNAME" >> ~/.pypirc
+echo -e "password = $PYPI_PASSWORD" >> ~/.pypirc
+
+# Ensure that we have the latest versions of Twine, Wheel, and Setuptools.
+python3 -m pip install --upgrade twine wheel setuptools
+
+# Build the distribution and upload.
+python3 setup.py bdist_wheel
+twine upload dist/*