Pub/Sub to Avro Files on Cloud Storage template

The Pub/Sub to Avro files on Cloud Storage template is a streaming pipeline that reads data from a Pub/Sub topic and writes Avro files into the specified Cloud Storage bucket.

Pipeline requirements

• The input Pub/Sub topic must exist prior to pipeline execution.

Template parameters

Parameter	Description
inputTopic	Pub/Sub topic to subscribe for message consumption. The topic name must be in the format of projects/<project-id>/topics/<topic-name>.
outputDirectory	Output directory where output Avro files are archived. Must contain / at the end. For example: gs://example-bucket/example-directory/.
avroTempDirectory	Directory for temporary Avro files. Must contain / at the end. For example: gs://example-bucket/example-directory/.
outputFilenamePrefix	(Optional) Output filename prefix for the Avro files.
outputFilenameSuffix	(Optional) Output filename suffix for the Avro files.
outputShardTemplate	(Optional) The shard template of the output file. It is specified as repeating sequences of the letters S or N. For example, SSS-NNN. These are replaced with either the shard number or the total number of shards, respectively. When this parameter is not specified, the default template format is W-P-SS-of-NN.

Run the template

Console

1. Go to the Dataflow Create job from template page.
Go to Create job from template
2. In the Job name field, enter a unique job name.
3. Optional: For Regional endpoint, select a value from the drop-down menu. The default region is us-central1.

   For a list of regions where you can run a Dataflow job, see Dataflow locations.

4. From the Dataflow template drop-down menu, select the Pub/Sub to Avro Files on Cloud Storage template.
5. In the provided parameter fields, enter your parameter values.
6. Click Run job.

gcloud

Note: To use the Google Cloud CLI to run classic templates, you must have Google Cloud CLI version 138.0.0 or later.

In your shell or terminal, run the template:

gcloud dataflow jobs run JOB_NAME \
    --gcs-location gs://dataflow-templates-REGION_NAME/VERSION/Cloud_PubSub_to_Avro \
    --region REGION_NAME \
    --staging-location STAGING_LOCATION \
    --parameters \
inputTopic=projects/PROJECT_ID/topics/TOPIC_NAME,\
outputDirectory=gs://BUCKET_NAME/output/,\
outputFilenamePrefix=FILENAME_PREFIX,\
outputFilenameSuffix=FILENAME_SUFFIX,\
outputShardTemplate=SHARD_TEMPLATE,\
avroTempDirectory=gs://BUCKET_NAME/temp/

Replace the following:

• JOB_NAME: a unique job name of your choice
• REGION_NAME: the region where you want to deploy your Dataflow job—for example, us-central1
• VERSION: the version of the template that you want to use

  You can use the following values:

  • latest to use the latest version of the template, which is available in the non-dated parent folder in the bucket— gs://dataflow-templates-REGION_NAME/latest/
  • the version name, like 2023-09-12-00_RC00, to use a specific version of the template, which can be found nested in the respective dated parent folder in the bucket— gs://dataflow-templates-REGION_NAME/
  Caution: The latest version of templates might update with breaking changes. Your production environments should use templates kept in the most recent dated parent folder to prevent these breaking changes from affecting your production workflows.
• STAGING_LOCATION: the location for staging local files (for example, gs://your-bucket/staging)
• TOPIC_NAME: the Pub/Sub topic name
• BUCKET_NAME: the name of your Cloud Storage bucket
• FILENAME_PREFIX: the preferred output filename prefix
• FILENAME_SUFFIX: the preferred output filename suffix
• SHARD_TEMPLATE: the preferred output shard template

API

To run the template using the REST API, send an HTTP POST request. For more information on the API and its authorization scopes, see projects.templates.launch.

POST https://dataflow.googleapis.com/v1b3/projects/PROJECT_ID/locations/LOCATION/templates:launch?gcsPath=gs://dataflow-templates-LOCATION/VERSION/Cloud_PubSub_to_Avro
{
   "jobName": "JOB_NAME",
   "environment": {
       "ipConfiguration": "WORKER_IP_UNSPECIFIED",
       "additionalExperiments": []
    },
   "parameters": {
       "inputTopic": "projects/PROJECT_ID/topics/TOPIC_NAME",
       "outputDirectory": "gs://BUCKET_NAME/output/",
       "avroTempDirectory": "gs://BUCKET_NAME/temp/",
       "outputFilenamePrefix": "FILENAME_PREFIX",
       "outputFilenameSuffix": "FILENAME_SUFFIX",
       "outputShardTemplate": "SHARD_TEMPLATE"
   }
}

Replace the following:

• PROJECT_ID: the Google Cloud project ID where you want to run the Dataflow job
• JOB_NAME: a unique job name of your choice
• LOCATION: the region where you want to deploy your Dataflow job—for example, us-central1
• VERSION: the version of the template that you want to use

  You can use the following values:

  • latest to use the latest version of the template, which is available in the non-dated parent folder in the bucket— gs://dataflow-templates-REGION_NAME/latest/
  • the version name, like 2023-09-12-00_RC00, to use a specific version of the template, which can be found nested in the respective dated parent folder in the bucket— gs://dataflow-templates-REGION_NAME/
  Caution: The latest version of templates might update with breaking changes. Your production environments should use templates kept in the most recent dated parent folder to prevent these breaking changes from affecting your production workflows.
• STAGING_LOCATION: the location for staging local files (for example, gs://your-bucket/staging)
• TOPIC_NAME: the Pub/Sub topic name
• BUCKET_NAME: the name of your Cloud Storage bucket
• FILENAME_PREFIX: the preferred output filename prefix
• FILENAME_SUFFIX: the preferred output filename suffix
• SHARD_TEMPLATE: the preferred output shard template

This template uses a fixed window, and data that arrives outside of the window might be discarded. To modify the template to change this behavior, see Extend templates.

Template source code

Java

/*
 * Copyright (C) 2018 Google LLC
 *
 * 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.
 */
package com.google.cloud.teleport.templates;

import com.google.cloud.teleport.avro.AvroPubsubMessageRecord;
import com.google.cloud.teleport.io.WindowedFilenamePolicy;
import com.google.cloud.teleport.metadata.Template;
import com.google.cloud.teleport.metadata.TemplateCategory;
import com.google.cloud.teleport.metadata.TemplateCreationParameter;
import com.google.cloud.teleport.metadata.TemplateParameter;
import com.google.cloud.teleport.options.WindowedFilenamePolicyOptions;
import com.google.cloud.teleport.templates.PubsubToAvro.Options;
import com.google.cloud.teleport.util.DurationUtils;
import org.apache.beam.sdk.Pipeline;
import org.apache.beam.sdk.PipelineResult;
import org.apache.beam.sdk.extensions.avro.io.AvroIO;
import org.apache.beam.sdk.io.FileBasedSink;
import org.apache.beam.sdk.io.fs.ResourceId;
import org.apache.beam.sdk.io.gcp.pubsub.PubsubIO;
import org.apache.beam.sdk.io.gcp.pubsub.PubsubMessage;
import org.apache.beam.sdk.options.Default;
import org.apache.beam.sdk.options.Description;
import org.apache.beam.sdk.options.PipelineOptions;
import org.apache.beam.sdk.options.PipelineOptionsFactory;
import org.apache.beam.sdk.options.StreamingOptions;
import org.apache.beam.sdk.options.Validation.Required;
import org.apache.beam.sdk.options.ValueProvider;
import org.apache.beam.sdk.options.ValueProvider.NestedValueProvider;
import org.apache.beam.sdk.transforms.DoFn;
import org.apache.beam.sdk.transforms.ParDo;
import org.apache.beam.sdk.transforms.SerializableFunction;
import org.apache.beam.sdk.transforms.windowing.FixedWindows;
import org.apache.beam.sdk.transforms.windowing.Window;
import org.apache.beam.sdk.values.PCollection;

/**
 * This pipeline ingests incoming data from a Cloud Pub/Sub topic and outputs the raw data into
 * windowed Avro files at the specified output directory.
 *
 * <p>Files output will have the following schema:
 *
 * <pre>
 *   {
 *      "type": "record",
 *      "name": "AvroPubsubMessageRecord",
 *      "namespace": "com.google.cloud.teleport.avro",
 *      "fields": [
 *        {"name": "message", "type": {"type": "array", "items": "bytes"}},
 *        {"name": "attributes", "type": {"type": "map", "values": "string"}},
 *        {"name": "timestamp", "type": "long"}
 *      ]
 *   }
 * </pre>
 *
 * <p>Check out <a
 * href="https://github.com/GoogleCloudPlatform/DataflowTemplates/blob/main/v1/README_Cloud_PubSub_to_Avro.md">README</a>
 * for instructions on how to use or modify this template.
 */
@Template(
    name = "Cloud_PubSub_to_Avro",
    category = TemplateCategory.STREAMING,
    displayName = "Pub/Sub to Avro Files on Cloud Storage",
    description =
        "The Pub/Sub to Avro files on Cloud Storage template is a streaming pipeline that reads data from a Pub/Sub "
            + "topic and writes Avro files into the specified Cloud Storage bucket.",
    optionsClass = Options.class,
    skipOptions = "inputSubscription",
    documentation =
        "https://cloud.google.com/dataflow/docs/guides/templates/provided/pubsub-to-avro",
    contactInformation = "https://cloud.google.com/support",
    requirements = {"The input Pub/Sub topic must exist prior to pipeline execution."},
    streaming = true,
    supportsAtLeastOnce = true)
public class PubsubToAvro {

  /**
   * Options supported by the pipeline.
   *
   * <p>Inherits standard configuration options.
   */
  public interface Options
      extends PipelineOptions, StreamingOptions, WindowedFilenamePolicyOptions {
    @TemplateParameter.PubsubSubscription(
        order = 1,
        description = "Pub/Sub input subscription",
        helpText =
            "Pub/Sub subscription to read the input from, in the format of"
                + " 'projects/your-project-id/subscriptions/your-subscription-name'",
        example = "projects/your-project-id/subscriptions/your-subscription-name")
    ValueProvider<String> getInputSubscription();

    void setInputSubscription(ValueProvider<String> value);

    @TemplateParameter.PubsubTopic(
        order = 2,
        description = "Pub/Sub input topic",
        helpText =
            "Pub/Sub topic to read the input from, in the format of "
                + "'projects/your-project-id/topics/your-topic-name'")
    ValueProvider<String> getInputTopic();

    void setInputTopic(ValueProvider<String> value);

    @TemplateCreationParameter(value = "false")
    @Description(
        "This determines whether the template reads from " + "a pub/sub subscription or a topic")
    @Default.Boolean(false)
    Boolean getUseSubscription();

    void setUseSubscription(Boolean value);

    @TemplateParameter.GcsWriteFolder(
        order = 4,
        description = "Output file directory in Cloud Storage",
        helpText =
            "The path and filename prefix for writing output files. Must end with a slash. DateTime"
                + " formatting is used to parse directory path for date & time formatters.")
    @Required
    ValueProvider<String> getOutputDirectory();

    void setOutputDirectory(ValueProvider<String> value);

    @TemplateParameter.Text(
        order = 5,
        optional = true,
        description = "Output filename prefix of the files to write",
        helpText = "The prefix to place on each windowed file.",
        regexes = "^[a-zA-Z\\-]+$")
    @Default.String("output")
    ValueProvider<String> getOutputFilenamePrefix();

    void setOutputFilenamePrefix(ValueProvider<String> value);

    @TemplateParameter.Text(
        order = 6,
        optional = true,
        description = "Output filename suffix of the files to write",
        helpText =
            "The suffix to place on each windowed file. Typically a file extension such "
                + "as .txt or .csv.")
    @Default.String("")
    ValueProvider<String> getOutputFilenameSuffix();

    void setOutputFilenameSuffix(ValueProvider<String> value);

    @TemplateParameter.GcsWriteFolder(
        order = 7,
        description = "Temporary Avro write directory",
        helpText = "Directory for temporary Avro files.")
    @Required
    ValueProvider<String> getAvroTempDirectory();

    void setAvroTempDirectory(ValueProvider<String> value);
  }

  /**
   * Main entry point for executing the pipeline.
   *
   * @param args The command-line arguments to the pipeline.
   */
  public static void main(String[] args) {

    Options options = PipelineOptionsFactory.fromArgs(args).withValidation().as(Options.class);
    options.setStreaming(true);

    run(options);
  }

  /**
   * Runs the pipeline with the supplied options.
   *
   * @param options The execution parameters to the pipeline.
   * @return The result of the pipeline execution.
   */
  public static PipelineResult run(Options options) {
    // Create the pipeline
    Pipeline pipeline = Pipeline.create(options);

    PCollection<PubsubMessage> messages = null;

    /*
     * Steps:
     *   1) Read messages from PubSub
     *   2) Window the messages into minute intervals specified by the executor.
     *   3) Output the windowed data into Avro files, one per window by default.
     */

    if (options.getUseSubscription()) {
      messages =
          pipeline.apply(
              "Read PubSub Events",
              PubsubIO.readMessagesWithAttributes()
                  .fromSubscription(options.getInputSubscription()));
    } else {
      messages =
          pipeline.apply(
              "Read PubSub Events",
              PubsubIO.readMessagesWithAttributes().fromTopic(options.getInputTopic()));
    }
    messages
        .apply("Map to Archive", ParDo.of(new PubsubMessageToArchiveDoFn()))
        .apply(
            options.getWindowDuration() + " Window",
            Window.into(FixedWindows.of(DurationUtils.parseDuration(options.getWindowDuration()))))

        // Apply windowed file writes. Use a NestedValueProvider because the filename
        // policy requires a resourceId generated from the input value at runtime.
        .apply(
            "Write File(s)",
            AvroIO.write(AvroPubsubMessageRecord.class)
                .to(
                    WindowedFilenamePolicy.writeWindowedFiles()
                        .withOutputDirectory(options.getOutputDirectory())
                        .withOutputFilenamePrefix(options.getOutputFilenamePrefix())
                        .withShardTemplate(options.getOutputShardTemplate())
                        .withSuffix(options.getOutputFilenameSuffix())
                        .withYearPattern(options.getYearPattern())
                        .withMonthPattern(options.getMonthPattern())
                        .withDayPattern(options.getDayPattern())
                        .withHourPattern(options.getHourPattern())
                        .withMinutePattern(options.getMinutePattern()))
                .withTempDirectory(
                    NestedValueProvider.of(
                        options.getAvroTempDirectory(),
                        (SerializableFunction<String, ResourceId>)
                            input -> FileBasedSink.convertToFileResourceIfPossible(input)))
                /*.withTempDirectory(FileSystems.matchNewResource(
                options.getAvroTempDirectory(),
                Boolean.TRUE))
                */
                .withWindowedWrites()
                .withNumShards(options.getNumShards()));

    // Execute the pipeline and return the result.
    return pipeline.run();
  }

  /**
   * Converts an incoming {@link PubsubMessage} to the {@link AvroPubsubMessageRecord} class by
   * copying its fields and the timestamp of the message.
   */
  static class PubsubMessageToArchiveDoFn extends DoFn<PubsubMessage, AvroPubsubMessageRecord> {
    @ProcessElement
    public void processElement(ProcessContext context) {
      PubsubMessage message = context.element();
      context.output(
          new AvroPubsubMessageRecord(
              message.getPayload(), message.getAttributeMap(), context.timestamp().getMillis()));
    }
  }
}

What's next

• Learn about Dataflow templates.
• See the list of Google-provided templates.