dataflow: workaround for beam base image bug (GoogleCloudPlatform#4899)

* dataflow: install libffi-dev explicitly

* Mention region explicitly in cleanup

Co-authored-by: Leah E. Cole <6719667+leahecole@users.noreply.github.com>

dataflow/flex-templates/streaming_beam/Dockerfile

@@ -18,6 +18,11 @@ ARG WORKDIR=/dataflow/template
 RUN mkdir -p ${WORKDIR}
 WORKDIR ${WORKDIR}
 
+# Due to a change in the Beam base image in version 2.24, we need to install
+# libffi-dev manually as a dependency. For more information:
+#   https://github.com/GoogleCloudPlatform/python-docs-samples/issues/4891
+RUN apt-get update && apt-get install -y libffi-dev && rm -rf /var/lib/apt/lists/*
+
 COPY requirements.txt .
 COPY streaming_beam.py .
 

dataflow/flex-templates/streaming_beam/README.md

@@ -224,7 +224,8 @@ The following sections describe how to delete or turn off these resources.
     gcloud dataflow jobs list \
         --filter 'NAME:streaming-beam AND STATE=Running' \
         --format 'value(JOB_ID)' \
-      | xargs gcloud dataflow jobs cancel
+        --region "$REGION" \
+      | xargs gcloud dataflow jobs cancel --region "$REGION"
     ```
 
 1. Delete the template spec file from Cloud Storage.