Fixed regressions due to automated dependency updates

demo-app/Dockerfile

@@ -12,7 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-FROM python:3.8.0b1-stretch
+FROM python:3.8.2-buster
 
 RUN apt-get update \
  && apt-get clean \

demo-app/app.py

@@ -20,21 +20,23 @@
 from flask import Flask, render_template, request
 
 from opencensus.trace import execution_context
-from opencensus.trace.exporters import stackdriver_exporter
-from opencensus.trace.exporters.transports import background_thread
-from opencensus.trace.ext.flask.flask_middleware import FlaskMiddleware
+from opencensus.common.transports.async_ import AsyncTransport
+from opencensus.ext.stackdriver import trace_exporter as stackdriver_exporter
+from opencensus.ext.flask.flask_middleware import FlaskMiddleware
 from opencensus.trace.propagation import google_cloud_format
-from opencensus.trace.samplers import always_on
+from opencensus.trace import samplers
+
 
 app = Flask(__name__)
 
 topic_name = 'tracing-demo'
 
 # Configure Tracing
 exporter = stackdriver_exporter.StackdriverExporter(
-    transport=background_thread.BackgroundThreadTransport)
+    transport=AsyncTransport)
+
 propagator = google_cloud_format.GoogleCloudFormatPropagator()
-sampler = always_on.AlwaysOnSampler()
+sampler = samplers.AlwaysOnSampler()
 blacklist_paths = ['favicon.ico']
 
 # Instrument Flask to do tracing automatically

demo-app/requirements.txt

@@ -1,6 +1,7 @@
 google-cloud-monitoring==0.31.1
 google-cloud-pubsub==0.42.1
 google-cloud-trace==0.21.0
-gunicorn==19.9.0
-opencensus==0.6.0
+gunicorn==20.0.4
+opencensus-ext-stackdriver==0.7.2
+opencensus-ext-flask==0.7.3
 Flask==1.1.1