Apache Beam streaming pipeline workshop

Step by step development of a streaming pipeline in Python using Apace Beam.

In this workshop we will develop a streaming pipeline, showing how to get data in JSON format and parse it (using Beam schemas), how to aggregate it and write out to files.

We will apply complex analytics to the stream, calculating properties of a session for different users, grouping together events of the same session by using windowing.

As a bonus point, we will explore how to use the parameters of a DoFn to inspect the properties of the window, adding information about the window and the trigger, to understand the concepts of windowing, triggering and accumulation mode.

Choosing the correct code branch

The "main" branch has the complete code for the streaming pipeline.

The "workshop" branch has code with gaps that are to be completed live in the workshop.

Checkout the "workshop" branch and challenge yourself !

git checkout workshop

Setting up your environment

Python 3.10

This is a hands on workshop, please come ready with Python 3.10 installed:

use the Python official downloads
use pyenv
follow the instructions for Google Cloud
...or whatever you prefer !

Development Environment

This is a hands on workshop, please come ready with a development environment:

VSCode
PyCharm
GCP cloud shell
GCP cloud shell editor
GCP workstation
...or whatever you prefer !

Python Virtual Env

With python pointing at python 3.10 run the following.

Create a virtual environment

python -m venv venv

Activate the virtual environment.

source venv/bin/activate

While activated, your python and pip commands will point to the virtual environment, so any changes or install dependencies are self-contained.

Initialize pipeline code

Execute form the root of this repo to initialze the pipeline code.

First, update pip before installing dependencies, it's always a good idea to do this.

pip install -U pip

Install the project as a local package, this installs all the dependencies as well.

pip install -e .

The taxi ride dataset being used in this workshop

The taxi tycoon dataset was created for this codelab:

https://github.com/googlecodelabs/cloud-dataflow-nyc-taxi-tycoon

It is a public pub/sub topic which is continuously updated. It is found here:

projects/pubsub-public-data/topics/taxirides-realtime

To save time, samples of this pub/sub topic have already been downloaded for you.

The following samples have been taking:

01_complete_ride*.txt are messages from rides with pickup,enroute & dropoff events
All other files differ according to how long we spent downlading the pubs/sub msgs
- 05min_of_rides.txt
- 10min_of_rides.txt
- 20min_of_rides.txt

Unzip the taxi ride datasets before executing the beam pipeline

To get around GitHub 100MB upload limit the samples of ride data messages were zip.

Unzip them before proceeding.

Execute form the root of this repo:

unzip data/input/05min_of_rides.zip -d data/input/
unzip data/input/10min_of_rides.zip -d data/input/
unzip data/input/20min_of_rides.zip -d data/input/

TESTS - Running the test suite for the pipeline

To run the all the tests

python -m unittest -v

To run just a single test

python -m unittest test.test_pipeline.TestTaxiPointCreation.test_task_1_taxi_point_creation

python -m unittest test.test_pipeline.TestAddTimestampDoFn.test_task_2_add_timestamp_dofn

python -m unittest test.test_pipeline.TestAddingKeysToTaxiRides.test_task_3_adding_keys_to_taxi_rides

python -m unittest test.test_pipeline.TestTaxiRideSessions.test_task_4_taxi_ride_sessions

python -m unittest test.test_pipeline.TestStatsCalculation.test_task_5_stats_calculation

python -m unittest test.test_pipeline.TestEndToEndPipeline.test_task_6_end_to_end_pipeline

DirectRunner - BATCH MODE - Executing beam pipeline to process taxi ride data

It is possible to run the pipeline using the DirectRunner in batch mode.

# batch mode
python main.py  \
  --runner DirectRunner \
  --save_main_session \
  --setup_file ./setup.py \
  --input_filename=data/input/01_complete_ride_277278c9-9e5e-4aa9-b1b9-3e38e2133e5f.txt \
  --output_filename=data/output/01_complete_ride_ride_analysis

DirectRunner - STREAMING MODE - Executing beam pipeline to process taxi ride data

It is possible to run the pipeline using the DirectRunner in streaming mode.

# streaming mode
python main.py  \
  --runner DirectRunner \
  --streaming \
  --save_main_session \
  --setup_file ./setup.py \
  --input_filename=data/input/01_complete_ride_277278c9-9e5e-4aa9-b1b9-3e38e2133e5f.txt \
  --output_filename=data/output/01_complete_ride_ride_analysis

However, because of this bug:

apache/beam#19070

Certain code will fail when using the DirectRunner in STREAMING mode.

For example, printing to stdout locally when trying to debug the pipeline.

DirectRunner - Details of each command line flag used:

Flag	Description
runner	Apache Beam execution engine or "runner", e.g. DirectRunner or DataflowRunner
streaming	If present, pipeline executes in streaming mode otherwise in batch mode
save_main_session	Make global imports availabe to all dataflow workers details
setup_file	To hanle Multiple File Dependencies details
input-filename	Custom. The input file to the pipeline.
output-filename	Custom. The output file of the pipeline

DataflowRunner - Executing beam pipeline to process taxi ride data

It is possible to run the pipeline using the Dataflow runner.

First create some evironmental variables as follows:

export GCP_PROJECT_ID=$(gcloud config list core/project --format="value(core.project)")

export GCP_PROJECT_NUM=$(gcloud projects describe $GCP_PROJECT_ID --format="value(projectNumber)")

export GCP_BUCKET_REGION="US"

export GCP_DATAFLOW_REGION="us-east4"

export GCS_BUCKET=gs://${GCP_PROJECT_ID}-beamsummit2023

export GCS_BUCKET_TMP=${GCS_BUCKET}/tmp/

export GCS_BUCKET_INPUT=${GCS_BUCKET}/input

export GCS_BUCKET_OUTPUT=${GCS_BUCKET}/output

export [email protected]

Next create a GCS bucket for temp, input & output data.

gcloud storage buckets create ${GCS_BUCKET} \
  --project=${GCP_PROJECT_ID} \
  --location=${GCP_BUCKET_REGION} \
  --uniform-bucket-level-access

gcloud storage buckets add-iam-policy-binding ${GCS_BUCKET} \
--member=allUsers \
--role=roles/storage.objectViewer

Next upload our taxi data into the newly created bucket

gcloud storage cp 01_complete_ride_277278c9-9e5e-4aa9-b1b9-3e38e2133e5f.txt ${GCS_BUCKET_INPUT}
gcloud storage cp 05min_of_rides.txt ${GCS_BUCKET_INPUT}
gcloud storage cp 10min_of_rides.txt ${GCS_BUCKET_INPUT}
gcloud storage cp 20min_of_rides.txt ${GCS_BUCKET_INPUT}

Next create authentication details for your Google account

gcloud auth application-default login

To successfully run Dataflow jobs, your user must have permissions to do so.

Run the following commands to update the permissions on your user.

gcloud projects add-iam-policy-binding ${GCP_PROJECT_ID} \
--member="user:${EMAIL_ADDRESS}" \
--role=roles/iam.serviceAccountUser

To successfully run Dataflow jobs, Dataflow service account must have resource access.

The Dataflow service account is the default GCP Project Compute Engine service account:

it executes dataflow, e.g. launching jobs
it accesses resources from dataflow workers, e.g. GCS buckets

Run the following commands to update permissions on this service account for dataflow:

gcloud projects add-iam-policy-binding ${GCP_PROJECT_ID} \
 --member="serviceAccount:${GCP_PROJECT_NUM}[email protected]" \
--role=roles/dataflow.admin

gcloud projects add-iam-policy-binding ${GCP_PROJECT_ID} \
 --member="serviceAccount:${GCP_PROJECT_NUM}[email protected]" \
--role=roles/dataflow.worker

gcloud projects add-iam-policy-binding ${GCP_PROJECT_ID} \
 --member="serviceAccount:${GCP_PROJECT_NUM}[email protected]" \
--role=roles/storage.objectAdmin

Using these environmental variables, the pipeline can be executed as follows:

# batch mode
python main.py  \
  --runner DataflowRunner \
  --save_main_session \
  --setup_file ./setup.py \
  --project ${GCP_PROJECT_ID} \
  --region ${GCP_DATAFLOW_REGION} \
  --temp_location ${GCS_BUCKET_TMP} \
  --input_filename=${GCS_BUCKET_INPUT}/01_complete_ride_277278c9-9e5e-4aa9-b1b9-3e38e2133e5f.txt \
  --output_filename=${GCS_BUCKET_OUTPUT}/01_complete_ride_analysis

# streaming mode
python main.py  \
  --runner DataflowRunner \
  --streaming \
  --save_main_session \
  --setup_file ./setup.py \
  --project ${GCP_PROJECT_ID} \
  --region ${GCP_DATAFLOW_REGION} \
  --temp_location ${GCS_BUCKET_TMP} \
  --input_filename=${GCS_BUCKET_INPUT}/01_complete_ride_277278c9-9e5e-4aa9-b1b9-3e38e2133e5f.txt \
  --output_filename=${GCS_BUCKET_OUTPUT}/01_complete_ride_analysis

Details of each flag used:

Flag	Description
runner	Apache Beam execution engine or "runner", e.g. DirectRunner or DataflowRunner
streaming	If present, pipeline executes in streaming mode otherwise in batch mode
save_main_session	Make global imports availabe to all dataflow workers details
setup_file	To hanle Multiple File Dependencies details
project	The GCP project where dataflow will execute
region	The GCP region where dataflow will execute
temp_location	A Temporary location for dataflow to use during execution
input_filename	Custom. The input file to the pipeline.
output_filename	Custom. The output file of the pipeline

Debugging the beam pipeline

Use the AnalyzeElement DoFn for info on PCollection elements, timestamps & windows.

You can configure the minimum & maximum expected timestamps for your pipeline.

This DoFn will use these to flag suspicious timestamps & windows as per this example:

####### BEGIN details of this element #####

>>>> element
{'ride_id': '277278c9-9e5e-4aa9-b1b9-3e38e2133e5f', 'point_idx': 278, 'latitude': 40.74541000000001, 'longitude': -73.98677, 'timestamp': '2023-04-21T16:37:24.7316-04:00', 'meter_reading': 17.25, 'meter_increment': 0.06205036, 'ride_status': 'dropoff', 'passenger_count': 2}
<class 'dict'>

>>>> timestamp
type(timestamp) -> <class 'apache_beam.utils.timestamp.Timestamp'>
timestamp.micros -> -9223372036854775000
timestamps on elements look incorrect, did you assign?

>>>>window
type(window) -> <class 'apache_beam.transforms.window.GlobalWindow'>
window.start -> Timestamp(-9223372036854.775000)
window.end -> Timestamp(9223371950454.775000)
windows on elements look incorrect, did you assign?


####### END details of this element #####

If the timestamp & windows values look fine you will a full output as per this example:

####### BEGIN details of this element #####

>>>> element
('277278c9-9e5e-4aa9-b1b9-3e38e2133e5f', {'ride_id': '277278c9-9e5e-4aa9-b1b9-3e38e2133e5f', 'point_idx': 278, 'latitude': 40.74541000000001, 'longitude': -73.98677, 'timestamp': '2023-04-21T16:37:24.7316-04:00', 'meter_reading': 17.25, 'meter_increment': 0.06205036, 'ride_status': 'dropoff', 'passenger_count': 2})
<class 'tuple'>

>>>> timestamp
type(timestamp) -> <class 'apache_beam.utils.timestamp.Timestamp'>
timestamp.micros -> 1682109444731600
timestamp.to_rfc3339() -> '2023-04-21T20:37:24.731600Z'
timestamp.to_utc_datetime() -> datetime.datetime(2023, 4, 21, 20, 37, 24, 731600)

>>>>window
type(window) -> <class 'apache_beam.transforms.window.IntervalWindow'>
window.start -> Timestamp(1682109444.731600)
window.start (utc datetime) -> 2023-04-21 20:37:24.731600 
window.end -> Timestamp(1682109474.731600)
window.end (utc datetime) -> 2023-04-21 20:37:54.731600 
window.max_timestamp() -> Timestamp(1682109474.731599) 
window.max_timestamp() (utc datetime) -> 2023-04-21 20:37:54.731599 


####### END details of this element #####

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