Java Database Connectivity (JDBC) to Pub/Sub template

Beta

This feature is subject to the "Pre-GA Offerings Terms" in the General Service Terms section of the Service Specific Terms. Pre-GA features are available "as is" and might have limited support. For more information, see the launch stage descriptions.

The Java Database Connectivity (JDBC) to Pub/Sub template is a batch pipeline that ingests data from JDBC source and writes the resulting records to a pre-existing Pub/Sub topic as a JSON string.

Pipeline requirements

• The JDBC source must exist prior to running the pipeline.
• The Pub/Sub output topic must exist prior to running the pipeline.

Template parameters

Required parameters

• driverClassName : The JDBC driver class name. (Example: com.mysql.jdbc.Driver).
• connectionUrl : The JDBC connection URL string. You can pass in this value as a string that's encrypted with a Cloud KMS key and then Base64-encoded. For example: 'echo -n "jdbc:mysql://some-host:3306/sampledb" | gcloud kms encrypt --location=
• driverJars : Comma-separated Cloud Storage paths for JDBC drivers. (Example: gs://your-bucket/driver_jar1.jar,gs://your-bucket/driver_jar2.jar).
• query : The query to run on the source to extract the data. (Example: select * from sampledb.sample_table).
• outputTopic : The Pub/Sub topic to publish to, in the format projects/<PROJECT_ID>/topics/<TOPIC_NAME>. (Example: projects/your-project-id/topics/your-topic-name).

Optional parameters

• username : The username to use for the JDBC connection. You can pass in this value as a string that's encrypted with a Cloud KMS key and then Base64-encoded. For example, echo -n 'some_username' | glcloud kms encrypt --location=my_location --keyring=mykeyring --key=mykey --plaintext-file=- --ciphertext-file=- | base64.
• password : The password to use for the JDBC connection. You can pass in this value as a string that's encrypted with a Cloud KMS key and then Base64-encoded. For example, echo -n 'some_password' | glcloud kms encrypt --location=my_location --keyring=mykeyring --key=mykey --plaintext-file=- --ciphertext-file=- | base64.
• connectionProperties : The properties string to use for the JDBC connection. The format of the string must be [propertyName=property;]*. (Example: unicode=true;characterEncoding=UTF-8).
• KMSEncryptionKey : The Cloud KMS Encryption Key to use to decrypt the username, password, and connection string. If a Cloud KMS key is passed in, the username, password, and connection string must all be passed in encrypted and base64 encoded. (Example: projects/your-project/locations/global/keyRings/your-keyring/cryptoKeys/your-key).
• disabledAlgorithms : Comma separated algorithms to disable. If this value is set to none, no algorithm is disabled. Use this parameter with caution, because the algorithms disabled by default might have vulnerabilities or performance issues. (Example: SSLv3, RC4).
• extraFilesToStage : Comma separated Cloud Storage paths or Secret Manager secrets for files to stage in the worker. These files are saved in the /extra_files directory in each worker. (Example: gs://

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 JDBC to Pub/Sub 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 flex templates, you must have Google Cloud CLI version 284.0.0 or later.

In your shell or terminal, run the template:

gcloud dataflow jobs run JOB_NAME \
    --gcs-location gs://dataflow-templates-REGION_NAME/VERSION/flex/Jdbc_to_PubSub \
    --region REGION_NAME \
    --parameters \
driverClassName=DRIVER_CLASS_NAME,\
connectionURL=JDBC_CONNECTION_URL,\
driverJars=DRIVER_PATHS,\
username=CONNECTION_USERNAME,\
password=CONNECTION_PASSWORD,\
connectionProperties=CONNECTION_PROPERTIES,\
query=SOURCE_SQL_QUERY,\
outputTopic=OUTPUT_TOPIC,\
KMSEncryptionKey=KMS_ENCRYPTION_KEY

Replace the following:

• JOB_NAME: a unique job name of your choice
• 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.
• REGION_NAME: the region where you want to deploy your Dataflow job—for example, us-central1
• DRIVER_CLASS_NAME: the driver class name
• JDBC_CONNECTION_URL: the JDBC connection URL
• DRIVER_PATHS: the comma-separated Cloud Storage path(s) of the JDBC driver(s)
• CONNECTION_USERNAME: the JDBC connection username
• CONNECTION_PASSWORD: the JDBC connection password
• CONNECTION_PROPERTIES: the JDBC connection properties, if necessary
• SOURCE_SQL_QUERY: the SQL query to be run on the source database
• OUTPUT_TOPIC: the Pub/Sub to publish to
• KMS_ENCRYPTION_KEY: the Cloud KMS Encryption Key

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/flexTemplates:launch
{
  "launchParameter": {
    "jobName": "JOB_NAME",
    "containerSpecGcsPath": "gs://dataflow-templates-LOCATION/VERSION/flex/Jdbc_to_PubSub"
    "parameters": {
      "driverClassName": "DRIVER_CLASS_NAME",
      "connectionURL": "JDBC_CONNECTION_URL",
      "driverJars": "DRIVER_PATHS",
      "username": "CONNECTION_USERNAME",
      "password": "CONNECTION_PASSWORD",
      "connectionProperties": "CONNECTION_PROPERTIES",
      "query": "SOURCE_SQL_QUERY",
      "outputTopic": "OUTPUT_TOPIC",
      "KMSEncryptionKey":"KMS_ENCRYPTION_KEY"
    },
    "environment": { "zone": "us-central1-f" }
  }
}

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
• 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.
• LOCATION: the region where you want to deploy your Dataflow job—for example, us-central1
• DRIVER_CLASS_NAME: the driver class name
• JDBC_CONNECTION_URL: the JDBC connection URL
• DRIVER_PATHS: the comma-separated Cloud Storage path(s) of the JDBC driver(s)
• CONNECTION_USERNAME: the JDBC connection username
• CONNECTION_PASSWORD: the JDBC connection password
• CONNECTION_PROPERTIES: the JDBC connection properties, if necessary
• SOURCE_SQL_QUERY: the SQL query to be run on the source database
• OUTPUT_TOPIC: the Pub/Sub to publish to
• KMS_ENCRYPTION_KEY: the Cloud KMS Encryption Key

Template source code

Java

/*
 * Copyright (C) 2021 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.v2.templates;

import static com.google.cloud.teleport.v2.utils.KMSUtils.maybeDecrypt;

import com.google.cloud.teleport.metadata.Template;
import com.google.cloud.teleport.metadata.TemplateCategory;
import com.google.cloud.teleport.v2.common.UncaughtExceptionLogger;
import com.google.cloud.teleport.v2.options.JdbcToPubsubOptions;
import java.sql.Clob;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import org.apache.beam.sdk.Pipeline;
import org.apache.beam.sdk.PipelineResult;
import org.apache.beam.sdk.coders.StringUtf8Coder;
import org.apache.beam.sdk.io.gcp.pubsub.PubsubIO;
import org.apache.beam.sdk.io.jdbc.JdbcIO;
import org.apache.beam.sdk.options.PipelineOptionsFactory;
import org.apache.beam.sdk.options.ValueProvider.StaticValueProvider;
import org.apache.beam.sdk.values.PCollection;
import org.json.JSONObject;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * The {@link JdbcToPubsub} batch pipeline reads data from JDBC and publishes to Google Cloud
 * PubSub.
 *
 * <p>Check out <a
 * href="https://github.com/GoogleCloudPlatform/DataflowTemplates/blob/main/v2/jdbc-to-googlecloud/README_Jdbc_to_PubSub.md">README</a>
 * for instructions on how to use or modify this template.
 */
@Template(
    name = "Jdbc_to_PubSub",
    category = TemplateCategory.BATCH,
    displayName = "JDBC to Pub/Sub",
    description =
        "The Java Database Connectivity (JDBC) to Pub/Sub template is a batch pipeline that ingests data from "
            + "JDBC source and writes the resulting records to a pre-existing Pub/Sub topic as a JSON string.",
    optionsClass = JdbcToPubsubOptions.class,
    flexContainerName = "jdbc-to-pubsub",
    documentation =
        "https://cloud.google.com/dataflow/docs/guides/templates/provided/jdbc-to-pubsub",
    contactInformation = "https://cloud.google.com/support",
    preview = true,
    requirements = {
      "The JDBC source must exist prior to running the pipeline.",
      "The Cloud Pub/Sub output topic must exist prior to running the pipeline."
    })
public class JdbcToPubsub {

  /* Logger for class.*/
  private static final Logger LOG = LoggerFactory.getLogger(JdbcToPubsub.class);

  /**
   * {@link JdbcIO.RowMapper} implementation to convert Jdbc ResultSet rows to UTF-8 encoded JSONs.
   */
  public static class ResultSetToJSONString implements JdbcIO.RowMapper<String> {

    @Override
    public String mapRow(ResultSet resultSet) throws Exception {
      ResultSetMetaData metaData = resultSet.getMetaData();
      JSONObject json = new JSONObject();

      for (int i = 1; i <= metaData.getColumnCount(); i++) {
        Object value = resultSet.getObject(i);

        // JSONObject.put() does not support null values. The exception is JSONObject.NULL
        if (value == null) {
          json.put(metaData.getColumnLabel(i), JSONObject.NULL);
          continue;
        }

        switch (metaData.getColumnTypeName(i).toLowerCase()) {
          case "clob":
            Clob clobObject = resultSet.getClob(i);
            if (clobObject.length() > Integer.MAX_VALUE) {
              LOG.warn(
                  "The Clob value size {} in column {} exceeds 2GB and will be truncated.",
                  clobObject.length(),
                  metaData.getColumnLabel(i));
            }
            json.put(
                metaData.getColumnLabel(i), clobObject.getSubString(1, (int) clobObject.length()));
            break;
          default:
            json.put(metaData.getColumnLabel(i), value);
        }
      }
      return json.toString();
    }
  }

  /**
   * Main entry point for pipeline execution.
   *
   * @param args Command line arguments to the pipeline.
   */
  public static void main(String[] args) {
    UncaughtExceptionLogger.register();

    JdbcToPubsubOptions options =
        PipelineOptionsFactory.fromArgs(args).withValidation().as(JdbcToPubsubOptions.class);

    run(options);
  }

  /**
   * Runs a pipeline which reads message from JDBC and writes to Pub/Sub.
   *
   * @param options The execution options.
   * @return The pipeline result.
   */
  public static PipelineResult run(JdbcToPubsubOptions options) {
    // Create the pipeline
    Pipeline pipeline = Pipeline.create(options);

    LOG.info("Starting Jdbc-To-PubSub Pipeline.");

    /*
     * Steps:
     *  1) Read data from a Jdbc Table
     *  2) Write to Pub/Sub topic
     */
    JdbcIO.DataSourceConfiguration dataSourceConfiguration =
        JdbcIO.DataSourceConfiguration.create(
                StaticValueProvider.of(options.getDriverClassName()),
                maybeDecrypt(options.getConnectionUrl(), options.getKMSEncryptionKey()))
            .withDriverJars(options.getDriverJars());
    if (options.getUsername() != null) {
      dataSourceConfiguration =
          dataSourceConfiguration.withUsername(
              maybeDecrypt(options.getUsername(), options.getKMSEncryptionKey()));
    }
    if (options.getPassword() != null) {
      dataSourceConfiguration =
          dataSourceConfiguration.withPassword(
              maybeDecrypt(options.getPassword(), options.getKMSEncryptionKey()));
    }
    if (options.getConnectionProperties() != null) {
      dataSourceConfiguration =
          dataSourceConfiguration.withConnectionProperties(options.getConnectionProperties());
    }

    PCollection<String> jdbcData =
        pipeline.apply(
            "readFromJdbc",
            JdbcIO.<String>read()
                .withDataSourceConfiguration(dataSourceConfiguration)
                .withQuery(options.getQuery())
                .withCoder(StringUtf8Coder.of())
                .withRowMapper(new ResultSetToJSONString()));

    jdbcData.apply("writeSuccessMessages", PubsubIO.writeStrings().to(options.getOutputTopic()));

    return pipeline.run();
  }
}

What's next

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