A Kafka Connect BigQuery sink connector
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README.md

Kafka Connect BigQuery Connector

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This is an implementation of a sink connector from Apache Kafka to Google BigQuery, built on top of Apache Kafka Connect.

Download

The latest releases are available in the GitHub release tab, or via tarballs in Maven central.

Standalone Quickstart

NOTE: You must have the Confluent Platform installed in order to run the example.

Configuration Basics

Firstly, you need to specify configuration settings for your connector. These can be found in the kcbq-connector/quickstart/properties/connector.properties file. Look for this section:

########################################### Fill me in! ###########################################
# The name of the BigQuery project to write to
project=
# The name of the BigQuery dataset to write to (leave the '.*=' at the beginning, enter your
# dataset after it)
datasets=.*=
# The location of a BigQuery service account JSON key file
keyfile=

You'll need to choose a BigQuery project to write to, a dataset from that project to write to, and provide the location of a JSON key file that can be used to access a BigQuery service account that can write to the project/dataset pair. Once you've decided on these properties, fill them in and save the properties file.

Once you get more familiar with the connector, you might want to revisit the connector.properties file and experiment with tweaking its settings.

Building and Extracting a Tarball

If you haven't already, move into the repository's top-level directory:

$ cd /path/to/kafka-connect-bigquery/

Begin by creating a tarball of the connector with the Confluent Schema Retriever included:

$ ./gradlew clean confluentTarBall

And then extract its contents:

$ mkdir bin/jar/ && tar -C bin/jar/ -xf bin/tar/kcbq-connector-*-confluent-dist.tar

Setting-Up Background Processes

Then move into the quickstart directory:

$ cd kcbq-connector/quickstart/

After that, if your Confluent Platform installation isn't in a sibling directory to the connector, specify its location (and do so before starting each of the subsequent processes in their own terminal):

$ export CONFLUENT_DIR=/path/to/confluent

Then, initialize the background processes necessary for Kafka Connect (one terminal per script): (Taken from http://docs.confluent.io/3.0.0/quickstart.html)

$ ./zookeeper.sh

(wait a little while for it to get on its feet)

$ ./kafka.sh

(wait a little while for it to get on its feet)

$ ./schema-registry.sh

(wait a little while for it to get on its feet)

Initializing the Avro Console Producer

Next, initialize the Avro Console Producer (also in its own terminal):

$ ./avro-console-producer.sh

Give it some data to start off with (type directly into the Avro Console Producer instance):

{"f1":"Testing the Kafka-BigQuery Connector!"}

Running the Connector

Finally, initialize the BigQuery connector (also in its own terminal):

$ ./connector.sh

Piping Data Through the Connector

Now you can enter Avro messages of the schema {"f1": "$SOME_STRING"} into the Avro Console Producer instance, and the pipeline instance should write them to BigQuery.

If you want to get more adventurous, you can experiment with different schemas or topics by adjusting flags given to the Avro Console Producer and tweaking the config settings found in the kcbq-connector/quickstart/properties directory.

Integration Testing the Connector

NOTE: You must have Docker installed and running on your machine in order to run integration tests for the connector.

This all takes place in the kcbq-connector directory.

How Integration Testing Works

Integration tests run by creating Docker instances for Zookeeper, Kafka, Schema Registry, and the BigQuery Connector itself, then verifying the results using a JUnit test.

They use schemas and data that can be found in the test/docker/populate/test_schemas/ directory, and rely on a user-provided JSON key file (like in the quickstart example) to access BigQuery.

The project and dataset they write to, as well as the specific JSON key file they use, can be specified by command-line flag, environment variable, or configuration file — the exact details of each can be found by running the integration test script with the -? flag.

Data Corruption Concerns

In order to ensure the validity of each test, any table that will be written to in the course of integration testing is preemptively deleted before the connector is run. This will only be an issue if you have any tables in your dataset whose names begin with kcbq_test_ and match the sanitized name of any of the test_schema subdirectories. If that is the case, you should probably consider writing to a different project/dataset.

Because Kafka and Schema Registry are run in Docker, there is no risk that running integration tests will corrupt any existing data that is already on your machine, and there is also no need to free up any of your ports that might currently be in use by real instances of the programs that are faked in the process of testing.

Running the Integration Tests

Running the series of integration tests is easy:

$ test/integrationtest.sh

This assumes that the project, dataset, and key file have been specified by variable or configuration file. For more information on how to specify these, run the test script with the --usage flag.

NOTE: You must have a recent version of boot2docker, Docker Machine, Docker, etc. installed. Older versions will hang when cleaning containers, and linking doesn't work properly.

Adding New Integration Tests

Adding an integration test is a little more involved, and consists of two major steps: specifying Avro data to be sent to Kafka, and specifying via JUnit test how to verify that such data made it to BigQuery as expected.

To specify input data, you must create a new directory in the test/resources/test_schemas/ directory with whatever name you want the Kafka topic of your test to be named, and whatever string you want the name of your test's BigQuery table to be derived from. Then, create two files in that directory:

  • schema.json will contain the Avro schema of the type of data the new test will send through the connector.

  • data.json will contain a series of JSON objects, each of which should represent an Avro record that matches the specified schema. Each JSON object must occupy its own line, and each object cannot occupy more than one line (this inconvenience is due to limitations in the Avro Console Producer, and may be addressed in future commits).

To specify data verification, add a new JUnit test to the file src/integration-test/java/com/wepay/kafka/connect/bigquery/it/BigQueryConnectorIntegrationTest.java. Rows that are retrieved from BigQuery in the test are only returned as Lists of Objects. The names of their columns are not tracked. Construct a List of the Objects that you expect to be stored in the test's BigQuery table, retrieve the actual List of Objects stored via a call to readAllRows(), and then compare the two via a call to testRows().

NOTE: Because the order of rows is not guaranteed when reading test results from BigQuery, you must include a row number as the first field of any of your test schemas, and every row of test data must have a unique value for its row number (row numbers are one-indexed).