Last Updated: Apr 18, 2024
This guide is for Beam users and developers who want to change or test Beam code. Specifically, this guide provides information about:
Testing code changes locally
Building Beam artifacts with modified Beam code and using the modified code for pipelines
The guide contains the following sections:
Repository structure: A description of the Apache Beam GitHub repository, including steps for setting up your Gradle project and for verifying the configuration of your develoment environment.
Java Guide: Guidance for setting up a Java environment, running and writing integration tests, and running a pipeline with modified Beam code.
Python Guide: Guidance for configuring your console for Python development, running unit and integration tests, and running a pipeline with modified Beam code.
The Apache Beam GitHub repository (Beam repo) is, for the most part, a “mono repo”. It contains everything in the Beam project, including the SDK, test infrastructure, dashboards, the Beam website, and the Beam Playground.
The following example code paths in the Beam repo are relevant for SDK development.
Java code paths are mainly found in two directories: sdks/java
and runners
. The following list provides notes about the contents of these directories and some of the subdirectories.
sdks/java
- Java SDK
sdks/java/core
- Java coresdks/java/harness
- SDK harness (entrypoint of SDK container)runners
- Java runner supports, including the following items:
runners/direct-java
- Java direct runnerrunners/flink-java
- Java Flink runnerrunners/google-cloud-dataflow-java
- Dataflow runner (job submission, translation, and so on)runners/google-cloud-dataflow-java/worker
- Worker for Dataflow jobs that don't use Runner v2For SDKs in other languages, the sdks/LANG
directory contains the relevant files. The following list provides notes about the contents of some of the subdirectories.
sdks/python
- Setup file and scripts to trigger test-suites
sdks/python/apache_beam
- The Beam packagesdks/python/apache_beam/runners/worker
- SDK worker harness entrypoint and state samplersdks/python/apache_beam/io
- I/O connectorssdks/python/apache_beam/transforms
- Most core componentssdks/python/apache_beam/ml
- Beam ML codesdks/python/apache_beam/runners
- Runner implementations and wrapperssdks/go
- Go SDK
.github/workflow
- GitHub action workflows, such as the tests that run during a pull request. Most workflows run a single Gradle command. To learn which command to run locally during development, during tests, check which command is running.
The Beam repo is a single Gradle project that contains all components, including Java, Python, Go, and the website. Before you begin development, familiarize yourself with the Gradle project structure by reviewing Structuring Projects with Gradle in the Gradle documentation.
Grade uses the following key concepts:
build.gradle
filebuild.gradle
filebuild.gradle
fileCommon tasks for a Java project or subproject include:
compileJava
- compiles the Java source filescompileTestJava
- compiles the Java test source filestest
- runs unit testsintegrationTest
- runs integration testsTo run a Gradle task, use the command ./gradlew -p <PROJECT_PATH> <TASK>
or the command ./gradlew :<PROJECT>:<PATH>:<TASK>
. For example:
./gradlew -p sdks/java/core compileJava ./gradlew :sdks:java:harness:test
For Apache Beam, one plugin manages everything: buildSrc/src/main/groovy/org/apache/beam/gradle/BeamModulePlugin
. The BeamModulePlugin
is used for the following tasks:
applyJavaNature
; for Python, use applyPythonNature
test
: run Java unit testsspotlessApply
: format Java codeIn every Java project or subproject, the build.gradle
file starts with the following code:
apply plugin: 'org.apache.beam.module' applyJavaNature( ... )
To set up a local development environment, first review the Contribution guide. If you plan to use Dataflow, you need to set up gcloud
credentials. To set up gcloud
credentials, see Create a Dataflow pipeline using Java in the Google Cloud documentation.
Depending on the languages involved, your PATH
file needs to have the following elements configured.
A Java environment that uses a supported Java version, preferably Java 8.
A Python environment that uses any supported Python version.
pyenv
and a virtual environment.A Go environment that uses latest Go version.
A Docker environment. This environment is needed for the following tasks:
The following list provides examples of when you need specific environemnts.
sdks/java/io/google-cloud-platform
, you need a Java environment.sdks/java/harness
, you need a Java environment, a Go environment, and Docker environment. You need the Docker environment to compile and build the Java SDK harness container image.sdks/python/apache_beam
, you need a Python environment.This section provides guidance for setting up your environment to modify or test Java code.
To set up IntelliJ, follow these steps. The IDE isn't required for changing the code and testing. You can run tests can by using a Gradle command line, as described in the Console setup section.
From IntelliJ, open /beam
(Important: Open the repository root directory, not sdks/java
).
Wait for indexing. Indexing might take a few minutes.
Because Gradle is a self-contained build tool, if the prerequisites are met, the environment setup is complete.
To verify whether the load is successful, follow these steps:
examples/java/build.gradle
.To run tests by using the Gradle command line (shell), in the command-line environment, run the following command. This command compiles the Apache Beam SDK, the WordCount pipeline, and a Hello-world program for data processing. It then runs the pipeline on the Direct Runner.
$ cd beam $ ./gradlew :examples:java:wordCount
When the command completes successfully, the following text appears in the Gradle build log:
... BUILD SUCCESSFUL in 2m 32s 96 actionable tasks: 9 executed, 87 up-to-date 3:41:06 PM: Execution finished 'wordCount'.
In addition, the following text appears in the output file:
$ head /tmp/output.txt* ==> /tmp/output.txt-00000-of-00003 <== should: 38 bites: 1 depraved: 1 gauntlet: 1 battle: 6 sith: 2 cools: 1 natures: 1 hedge: 1 words: 9 ==> /tmp/output.txt-00001-of-00003 <== elements: 1 Advise: 2 fearful: 2 towards: 4 ready: 8 pared: 1 left: 8 safe: 4 canst: 7 warrant: 2 ==> /tmp/output.txt-00002-of-00003 <== chanced: 1 ...
This section explains how to run unit tests locally after you make a code change in the Java SDK, for example, in sdks/java/io/jdbc
.
Tests are stored in the src/test/java
folder of each project. Unit tests have the filename .../**Test.java
. Integration tests have the filename .../**IT.java
.
To run all unit tests under a project, use the following command:
./gradlew :sdks:java:harness:test
Find the JUnit report in an HTML file in the file path <invoked_project>/build/reports/tests/test/index.html
.
To run a specific test, use the following commands:
./gradlew :sdks:java:harness:test --tests org.apache.beam.fn.harness.CachesTest ./gradlew :sdks:java:harness:test --tests *CachesTest ./gradlew :sdks:java:harness:test --tests *CachesTest.testClearableCache
To run tests using IntelliJ, click the ticks to run either a whole test class or a specific test. To debug the test, set breakpoints.
These steps don‘t apply to sdks:java:core
tests. To invoke those unit tests, use the command :runners:direct-java:needsRunnerTest
. Java core doesn’t depend on a runner. Therefore, unit tests that run a pipeline require the Direct Runner.
To run integration tests, use the Direct Runner.
Integration tests have the filename .../**IT.java
. They use TestPipeline
. Set options by using TestPipelineOptions
.
Integration tests differ from standard pipelines in the following ways:
TestDataflowRunner
).beamTestPipelineOptions
.To configure the test, you need to set the property -DbeamTestPipelineOptions=[...]
. This property sets the runner that the test uses.
The following example demonstrates how to run an integration test by using the command line. This example includes the options required to run the pipeline on the Dataflow runner.
-DbeamTestPipelineOptions='["--runner=TestDataflowRunner","--project=mygcpproject","--region=us-central1","--stagingLocation=gs://mygcsbucket/path"]'
To set up a TestPipeline
object in an integration test, use the following code:
@Rule public TestPipeline pipelineWrite = TestPipeline.create(); @Test public void testSomething() { pipeline.apply(...); pipeline.run().waitUntilFinish(); }
The task that runs the test needs to specify the runner. The following examples demonstrate how to specify the runner:
:sdks:java:io:google-cloud-platform:integrationTest
.:runners:google-cloud-dataflow-java:googleCloudPlatformLegacyWorkerIntegrationTest
.:runners:google-cloud-dataflow-java:googleCloudPlatformRunnerV2IntegrationTest
.To see how to run your workflow locally, refer to the Gradle command that the GitHub Action workflow runs.
The following commands demonstrate an example invocation:
./gradlew :runners:google-cloud-dataflow-java:examplesJavaRunnerV2IntegrationTest \ -PdisableSpotlessCheck=true -PdisableCheckStyle=true -PskipCheckerFramework \ -PgcpProject=<your_gcp_project> -PgcpRegion=us-central1 \ -PgcsTempRoot=gs://<your_gcs_bucket>/tmp
To apply code changes to your pipeline, we recommend that you start with a separate branch.
If you're making a pull request or want to test a change with the dev branch, start from Beam HEAD (master).
If you're making a patch on released Beam (2.xx.0), start from a tag, such as v2.55.0. Then, in the Beam repo, use the following command to compile the project that includes the code change. This example modifies sdks/java/io/kafka
.
./gradlew -Ppublishing -p sdks/java/io/kafka publishToMavenLocal
By default, this command publishes the artifact with modified code to the Maven Local repository (~/.m2/repository
). The change is picked up when the user pipeline runs.
If your code change is made in a development branch, such as on Beam master or a PR, the artifact is produced under version 2.xx.0-SNAPSHOT
instead of on a release tag. To pick up this dependency, you need to make additional configurations in your pipeline project. The following examples provide guidance for making configurations in Maven and Gradle.
Follow these steps for Maven projects.
Recommended: Use the WordCount maven-archetype
as a template to set up your project (https://beam.apache.org/get-started/quickstart-java/).
To add a snapshot repository, include the following elements:
<repository> <id>Maven-Snapshot</id> <name>maven snapshot repository</name> <url>https://repository.apache.org/content/groups/snapshots/</url> </repository>
In the pom.xml
file, modify the value of beam.version
:
<properties> <beam.version>2.XX.0-SNAPSHOT</beam.version>
Follow these steps for Gradle projects.
In the build.gradle
file, add the following code:
repositories { maven { url "https://repository.apache.org/content/groups/snapshots" } }
Set the Beam dependency versions to the following value: 2.XX.0-SNAPSHOT
.
This configuration directs the build system to download Beam nightly builds from the Maven Snapshot Repository. The local build that you edited isn‘t downloaded. You usually don’t need to build all Beam artifacts locally. If you do need to build all Beam artifacts locally, use the following command for all projects ./gradlew -Ppublishing publishToMavenLocal
.
The following situations require additional consideration.
If you're using the standard Dataflow runner (not Runner v2), and the worker harness has changed, do the following:
Use the following command to compile dataflowWorkerJar
:
./gradlew :runners:google-cloud-dataflow-java:worker:shadowJar
The jar is located in the build output.
Use the following command to pass pipelineOption
:
--dataflowWorkerJar=/.../beam-runners-google-cloud-dataflow-java-legacy-worker-2.XX.0-SNAPSHOT.jar
If you're using Dataflow Runner v2 and sdks/java/harness
or its dependencies (like sdks/java/core
) have changed, do the following:
Use the following command to build the SDK harness container:
./gradlew :sdks:java:container:java8:docker # java8, java11, java17, etc
docker tag apache/beam_java8_sdk:2.49.0.dev
“us.gcr.io/apache-beam-testing/beam_java11_sdk:2.49.0-custom” # change to your container registry docker push “us.gcr.io/apache-beam-testing/beam_java11_sdk:2.49.0-custom” ```
--experiments=use_runner_v2 \ --sdkContainerImage="us.gcr.io/apache-beam-testing/beam_java11_sdk:2.49.0-custom"
The Beam Python SDK is distributed as a single wheel, which is more straightforward than the Java SDK.
These instructions explain how to configure your console (shell) for Python development. In this example, the working directory is set to sdks/python
.
Recommended: Install the Python interpreter by using pyenv
. Use the following commands:
install prerequisites
curl https://pyenv.run | bash
pyenv install 3.X
(a supported Python version; see python_version
in project property
Use the following commands to set up and activate the virtual environment:
pyenv virtualenv 3.X ENV_NAME
pyenv activate ENV_NAME
Install the apache_beam
package in editable mode: pip install -e .[gcp, test]
For development that uses an SDK container image, do the following:
Install Docker Desktop.
Install Go.
If you're going to submit PRs, use the following command to precommit the hook for Python code changes (nobody likes lint failures!!):
# enable pre-commit (env) $ pip install pre-commit (env) $ pre-commit install # disable pre-commit (env) $ pre-commit uninstall
Although the tests can be triggered with a Gradle command, that method sets up a new virtualenv
and installs dependencies before each run, which takes minutes. Therefore, it's useful to have a persistent virtualenv
.
Unit tests have the filename **_test.py
.
To run all tests in a file, use the following command:
pytest -v apache_beam/io/textio_test.py
To run all tests in a class, use the following command:
pytest -v apache_beam/io/textio_test.py::TextSourceTest
To run a specific test, use the following command:
pytest -v apache_beam/io/textio_test.py::TextSourceTest::test_progress
Integration tests have the filename **_it_test.py
.
To run an integration test on the Direct Runner, use the following command:
python -m pytest -o log_cli=True -o log_level=Info \ apache_beam/ml/inference/pytorch_inference_it_test.py::PyTorchInference \ --test-pipeline-options='--runner=TestDirectRunner’
If you're preparing a PR, for test-suites to run in PostCommit Python, add tests paths under batchTests
in the common.gradle
file.
To run an integration test on the Dataflow Runner, follow these steps:
cd sdks/python pip install build && python -m build --sdist
The tarball file is generated in the sdks/python/sdist/
directory.
--test-pipeline-options
parameter. Use the location --sdk_location=dist/apache-beam-2.53.0.dev0.tar.gz
. The following example shows the complete command:python -m pytest -o log_cli=True -o log_level=Info \ apache_beam/ml/inference/pytorch_inference_it_test.py::PyTorchInference \ --test-pipeline-options='--runner=TestDataflowRunner --project=<project> --temp_location=gs://<bucket>/tmp --sdk_location=dist/apache-beam-2.35.0.dev0.tar.gz --region=us-central1’
@pytest.mark.it_postcommit
.To build containers for modified SDK code, follow these steps.
./gradlew :sdks:python:container:py39:docker \ -Pdocker-repository-root=<gcr.io/location> -Pdocker-tag=<tag>
--sdk_container_image
option.The following example shows a complete command:
python -m pytest -o log_cli=True -o log_level=Info \ apache_beam/ml/inference/pytorch_inference_it_test.py::PyTorchInference \ --test-pipeline-options='--runner=TestDataflowRunner --project=<project> --temp_location=gs://<bucket>/tmp --sdk_container_image=us.gcr.io/apache-beam-testing/beam-sdk/beam:dev --region=us-central1’
This section provides two options for specifying additional test dependencies.
Use the --requirements_file
options. The following example demonstrates how to use the --requirements_file
options:
python -m pytest -o log_cli=True -o log_level=Info \ apache_beam/ml/inference/pytorch_inference_it_test.py::PyTorchInference \ --test-pipeline-options='--runner=TestDataflowRunner --project=<project> --temp_location=gs://<bucket>/tmp --sdk_location=us.gcr.io/apache-beam-testing/beam-sdk/beam:dev --region=us-central1 –requirements_file=requirements.txt’
If you're using the Dataflow runner, use custom containers. You can use the official Beam SDK container image as a base and then apply your changes.
To run your pipeline with modified beam code, follow these steps:
Build the Beam SDK tarball. Under sdks/python
, run python -m build --sdist
. For more details, see Run an integration test on this page.
Install the Apache Beam Python SDK in your Python virtual environment with the necessary extensions. Use a command similar to the following example: pip install /path/to/apache-beam.tar.gz[gcp]
.
Initiate your Python script. To run your pipeline, use a command similar to the following example:
python my_pipeline.py --runner=DataflowRunner --sdk_location=/path/to/apache-beam.tar.gz --project=my_project --region=us-central1 --temp_location=gs://my-bucket/temp ...
Tips for using the Dataflow runner:
The Python worker installs the Apache Beam SDK before processing work items. Therefore, you don‘t usually need to provide a custom worker container. If your Google Cloud VM doesn’t have internet access and transient dependencies are changed from the officially released container images, you do need to provide a custom worker container. In this case, see Build containers for modified SDK code on this page.
Installing the Beam Python SDK from source can be slow (3.5 minutes for an1-standard-1
machine). As an alternative, if the host machine uses amd64 architecture, you can build a wheel instead of a tarball by using a command similar to ./gradle :sdks:python:bdistPy311linux
(for Python 3.11). To pass the built wheel, use the --sdk_location
option. That installation completes in seconds.
save_main_session
NameError
when running DoFn
on remote runner--save_main_session
pipeline option to enable it