Google Cloud Spanner Sink Connector for Confluent Cloud¶
The fully-managed Google Cloud Spanner Sink connector for Confluent Cloud moves data from Apache Kafka® to a Google Cloud Spanner database. It writes data from a topic in Kafka to a table in the specified Spanner database. Table auto-creation and limited auto-evolution are supported.
Note
This is a Quick Start for the fully-managed cloud connector. If you are installing the connector locally for Confluent Platform, see Google Cloud Spanner Sink Connector for Confluent Platform.
Features¶
The Google Cloud Spanner Sink connector provides the following features:
- The connector inserts and upserts Kafka records into a Google Cloud Spanner database.
- The connector supports Avro, JSON Schema, Protobuf, or JSON (schemaless) input data formats. Schema Registry must be enabled to use a Schema Registry-based format (for example, Avro, JSON_SR (JSON Schema), or Protobuf).
auto.create
andauto-evolve
are supported. If tables or columns are missing, they can be created automatically.- PK modes supported are
kafka``and ``record_value
. Used in conjunction with the PK Fields property.
For more information and examples to use with the Confluent Cloud API for Connect, see the Confluent Cloud API for Connect Usage Examples section.
Limitations¶
Be sure to review the following information.
- For connector limitations, see Google Cloud Spanner Sink Connector limitations.
- If you plan to use one or more Single Message Transforms (SMTs), see SMT Limitations.
- If you plan to use Confluent Cloud Schema Registry, see Schema Registry Enabled Environments.
Quick Start¶
Use this quick start to get up and running with the Confluent Cloud Google Cloud Spanner Sink connector. The quick start provides the basics of selecting the connector and configuring it to stream events to a Spanner database.
- Prerequisites
- Authorized access to a Confluent Cloud cluster on Google Cloud.
- The Confluent CLI installed and configured for the cluster. See Install the Confluent CLI.
- Schema Registry must be enabled to use a Schema Registry-based format (for example, Avro, JSON_SR (JSON Schema), or Protobuf). See Schema Registry Enabled Environments for additional information.
- An operating Google Cloud Spanner instance and database (a table can be auto-created). For the steps necessary to create an instance using the Google Cloud Console, see Quickstart using the console.
- A Google Cloud service account. You download service account credentials as a JSON file. These credentials are used when setting up the connector configuration.
- Kafka cluster credentials. The following lists the different ways you can provide credentials.
- Enter an existing service account resource ID.
- Create a Confluent Cloud service account for the connector. Make sure to review the ACL entries required in the service account documentation. Some connectors have specific ACL requirements.
- Create a Confluent Cloud API key and secret. To create a key and secret, you can use confluent api-key create or you can autogenerate the API key and secret directly in the Cloud Console when setting up the connector.
Using the Confluent Cloud Console¶
Step 1: Launch your Confluent Cloud cluster¶
See the Quick Start for Confluent Cloud for installation instructions.
Step 2: Add a connector¶
In the left navigation menu, click Connectors. If you already have connectors in your cluster, click + Add connector.
Step 4: Enter the connector details¶
Note
- Ensure you have all your prerequisites completed.
- An asterisk ( * ) designates a required entry.
At the Add Google Cloud Spanner Sink Connector screen, complete the following:
If you’ve already populated your Kafka topics, select the topics you want to connect from the Topics list.
To create a new topic, click +Add new topic.
- Select the way you want to provide Kafka Cluster credentials. You can
choose one of the following options:
- My account: This setting allows your connector to globally access everything that you have access to. With a user account, the connector uses an API key and secret to access the Kafka cluster. This option is not recommended for production.
- Service account: This setting limits the access for your connector by using a service account. This option is recommended for production.
- Use an existing API key: This setting allows you to specify an API key and a secret pair. You can use an existing pair or create a new one. This method is not recommended for production environments.
Note
Freight clusters support only service accounts for Kafka authentication.
- Click Continue.
- Upload your Google Cloud credentials JSON file.
- In the Spanner instance ID field, enter the ID of the Spanner instance to connect to.
- In the Spanner database ID field, enter the database ID where tables are located or will be created.
- Click Continue.
Note
Configuration properties that are not shown in the Cloud Console use the default values. See Configuration Properties for all property values and definitions.
Select the Input Kafka record value format (data coming from the Kafka topic): AVRO, JSON_SR, or PROTOBUF. A valid schema must be available in Schema Registry to use a schema-based message format (for example, Avro, JSON Schema, or Protobuf).
Select an insert mode:
INSERT
: Use the standardINSERT
row function. An error occurs if the row already exists in the table.UPSERT
: This mode is similar toINSERT
. However, if the row already exists, theUPSERT
function overwrites column values with the new values provided.
Show advanced configurations
Schema context: Select a schema context to use for this connector, if using a schema-based data format. This property defaults to the Default context, which configures the connector to use the default schema set up for Schema Registry in your Confluent Cloud environment. A schema context allows you to use separate schemas (like schema sub-registries) tied to topics in different Kafka clusters that share the same Schema Registry environment. For example, if you select a non-default context, a Source connector uses only that schema context to register a schema and a Sink connector uses only that schema context to read from. For more information about setting up a schema context, see What are schema contexts and when should you use them?.
Table name format: A format string for the destination table name, which may contain
${topic}
as a placeholder for the originating topic name. For example, to create a table namedkafka-orders
based on a Kafka topic namedorders
, you would enterkafka-${topic}
in this field.PK mode: The primary key mode.
PK Fields: List of comma-separated primary key field names.
Max batch size: The maximum number of records that can be batched into a single insert, or upsert, to Spanner.
Auto create table: Whether to automatically create the destination table if it is missing.
Auto add columns: Whether to automatically add columns in the table if they are missing.
Auto-restart policy
Enable Connector Auto-restart: Control the auto-restart behavior of the connector and its task in the event of user-actionable errors. Defaults to
true
, enabling the connector to automatically restart in case of user-actionable errors. Set this property tofalse
to disable auto-restart for failed connectors. In such cases, you would need to manually restart the connector.
Consumer configuration
Max poll interval(ms): Set the maximum delay between subsequent consume requests to Kafka. Use this property to improve connector performance in cases when the connector cannot send records to the sink system. The default is 300,000 milliseconds (5 minutes).
Max poll records: Set the maximum number of records to consume from Kafka in a single request. Use this property to improve connector performance in cases when the connector cannot send records to the sink system. The default is 500 records.
Transforms
Single Message Transforms: To add a new SMT, see Add transforms. For more information about unsupported SMTs, see Unsupported transformations.
See Configuration Properties for all property values and definitions.
Click Continue.
Based on the number of topic partitions you select, you will be provided with a recommended number of tasks.
- To change the number of recommended tasks, enter the number of tasks for the connector to use in the Tasks field.
- Click Continue.
Step 5: Check the results in Spanner¶
- From the Google Cloud Console, go to your Spanner project.
- Verify that new records are being added to the Spanner database.
For more information and examples to use with the Confluent Cloud API for Connect, see the Confluent Cloud API for Connect Usage Examples section.
Tip
When you launch a connector, a Dead Letter Queue topic is automatically created. See View Connector Dead Letter Queue Errors in Confluent Cloud for details.
Using the Confluent CLI¶
Complete the following steps to set up and run the connector using the Confluent CLI.
Note
Make sure you have all your prerequisites completed.
Step 1: List the available connectors¶
Enter the following command to list available connectors:
confluent connect plugin list
Step 2: List the connector configuration properties¶
Enter the following command to show the connector configuration properties:
confluent connect plugin describe <connector-plugin-name>
The command output shows the required and optional configuration properties.
Step 3: Create the connector configuration file¶
Create a JSON file that contains the connector configuration properties. The following example shows required and optional connector properties:
{
"connector.class": "SpannerSink",
"name": "spanner-sink-connector",
"kafka.auth.mode": "KAFKA_API_KEY",
"kafka.api.key": "<my-kafka-api-key?",
"kafka.api.secret": "<my-kafka-api-secret>",
"topics": "pageviews",
"input.data.format": "AVRO",
"gcp.spanner.credentials.json": "<my-gcp-credentials>",
"gcp.spanner.instance.id": "<my-spanner-instance-id>",
"gcp.spanner.database.id": "<my-spanner-database-id>",
"auto.create": "true",
"auto.evolve": "true",
"tasks.max": "1"
}
Note the following property definitions:
"connector.class"
: Identifies the connector plugin name."name"
: Sets a name for your new connector.
"kafka.auth.mode"
: Identifies the connector authentication mode you want to use. There are two options:SERVICE_ACCOUNT
orKAFKA_API_KEY
(the default). To use an API key and secret, specify the configuration propertieskafka.api.key
andkafka.api.secret
, as shown in the example configuration (above). To use a service account, specify the Resource ID in the propertykafka.service.account.id=<service-account-resource-ID>
. To list the available service account resource IDs, use the following command:confluent iam service-account list
For example:
confluent iam service-account list Id | Resource ID | Name | Description +---------+-------------+-------------------+------------------- 123456 | sa-l1r23m | sa-1 | Service account 1 789101 | sa-l4d56p | sa-2 | Service account 2
"topics"
: Identifies the topic name or a comma-separated list of topic names."input.data.format"
: Sets the input Kafka record value format (data coming from the Kafka topic). Valid entries are AVRO, JSON_SR, PROTOBUF, or JSON. You must have Confluent Cloud Schema Registry configured if using a schema-based message format (for example, Avro, JSON_SR (JSON Schema), or Protobuf)."gcp.spanner.credentials.json"
: This contains the contents of the downloaded JSON file. See Formatting Google Cloud credentials for details about how to format and use the contents of the downloaded credentials file."tasks.max"
: Maximum number of tasks the connector can run. See Confluent Cloud connector limitations for additional task information.
Optional
"auto.create"
(tables) and"auto-evolve"
(columns): Sets whether to automatically create tables or columns if they are missing relative to the input record schema. If not entered in the configuration, both default tofalse
."pk.mode"
: (Optional) Supported modes are listed below:kafka
: Kafka coordinates are used as the primary key. Must be used with the PK Fields property.record_value
: Fields from the Kafka record value are used. This must be a struct type.
"pk.fields"
: A list of comma-separated primary key field names. The runtime interpretation of this property depends on thepk.mode
selected. Options are listed below:kafka
: Must be three values representing the Kafka coordinates. If left empty, the coordinates default to__connect_topic,__connect_partition,__connect_offset
.none
: PK Fields not used.record_value
: Used to extract fields from the record value. If left empty, all fields from the value struct are used.
Single Message Transforms: See the Single Message Transforms (SMT) documentation for details about adding SMTs using the CLI. See Unsupported transformations for a list of SMTs that are not supported with this connector.
See Configuration Properties for all property values and definitions.
Formatting Google Cloud credentials¶
The contents of the downloaded credentials file must be converted to string format before it can be used in the connector configuration.
Convert the JSON file contents into string format.
Add the
\
escape character before all\n
entries in the Private Key section so that each section begins with\\n
(see the highlighted lines below). The example below has been formatted so that the\\n
entries are easier to see. Most of the credentials key has been omitted.Tip
A script is available that converts the credentials to a string and also adds additional escape
\
characters where needed. See Stringify Google Cloud Credentials.{ "connector.class": "SpannerSink", "name": "spanner-sink-connector", "kafka.api.key": "<my-kafka-api-key?", "kafka.api.secret": "<my-kafka-api-secret>", "topics": "pageviews", "input.data.format": "AVRO", "gcp.spanner.credentials.json": "{\"type\":\"service_account\",\"project_id\":\"connect- 1234567\",\"private_key_id\":\"omitted\", \"private_key\":\"-----BEGIN PRIVATE KEY----- \\nMIIEvAIBADANBgkqhkiG9w0BA \\n6MhBA9TIXB4dPiYYNOYwbfy0Lki8zGn7T6wovGS5pzsIh \\nOAQ8oRolFp\rdwc2cC5wyZ2+E+bhwn \\nPdCTW+oZoodY\\nOGB18cCKn5mJRzpiYsb5eGv2fN\/J \\n...rest of key omitted... \\n-----END PRIVATE KEY-----\\n\", \"client_email\":\"pub-sub@connect-123456789.iam.gserviceaccount.com\", \"client_id\":\"123456789\",\"auth_uri\":\"https:\/\/accounts.google.com\/o\/oauth2\/ auth\",\"token_uri\":\"https:\/\/oauth2.googleapis.com\/ token\",\"auth_provider_x509_cert_url\":\"https:\/\/ www.googleapis.com\/oauth2\/v1\/ certs\",\"client_x509_cert_url\":\"https:\/\/www.googleapis.com\/ robot\/v1\/metadata\/x509\/pub-sub%40connect- 123456789.iam.gserviceaccount.com\"}", "gcp.spanner.instance.id": "<my-spanner-instance-id>", "gcp.spanner.database.id": "<my-spanner-database-id>", "auto.create": "true", "auto.evolve": "true", "tasks.max": "1" }
Add all the converted string content to the credentials section of your configuration file as shown in the example above.
Step 4: Load the configuration file and create the connector¶
Enter the following command to load the configuration and start the connector:
confluent connect cluster create --config-file <file-name>.json
For example:
confluent connect cluster create --config-file spanner-sink-config.json
Example output:
Created connector spanner-sink-connector lcc-ix4dl
Step 5: Check the connector status¶
Enter the following command to check the connector status:
confluent connect cluster list
Example output:
ID | Name | Status | Type
+-----------+-------------------------+---------+------+
lcc-ix4dl | spanner-sink-connector | RUNNING | sink
Step 6: Check the results in Spanner.¶
- From the Google Cloud Console, go to your Spanner project.
- Verify that new records are being added to the Spanner database.
For more information and examples to use with the Confluent Cloud API for Connect, see the Confluent Cloud API for Connect Usage Examples section.
Tip
When you launch a connector, a Dead Letter Queue topic is automatically created. See View Connector Dead Letter Queue Errors in Confluent Cloud for details.
Configuration Properties¶
Use the following configuration properties with the fully-managed connector. For self-managed connector property definitions and other details, see the connector docs in Self-managed connectors for Confluent Platform.
Which topics do you want to get data from?¶
topics
Identifies the topic name or a comma-separated list of topic names.
- Type: list
- Importance: high
Schema Config¶
schema.context.name
Add a schema context name. A schema context represents an independent scope in Schema Registry. It is a separate sub-schema tied to topics in different Kafka clusters that share the same Schema Registry instance. If not used, the connector uses the default schema configured for Schema Registry in your Confluent Cloud environment.
- Type: string
- Default: default
- Importance: medium
Input messages¶
input.data.format
Sets the input Kafka record value format. Valid entries are AVRO, JSON_SR, or PROTOBUF. Note that you need to have Confluent Cloud Schema Registry configured if using a schema-based message format like AVRO, JSON_SR, and PROTOBUF.
- Type: string
- Default: JSON
- Importance: high
How should we connect to your data?¶
name
Sets a name for your connector.
- Type: string
- Valid Values: A string at most 64 characters long
- Importance: high
Kafka Cluster credentials¶
kafka.auth.mode
Kafka Authentication mode. It can be one of KAFKA_API_KEY or SERVICE_ACCOUNT. It defaults to KAFKA_API_KEY mode.
- Type: string
- Default: KAFKA_API_KEY
- Valid Values: KAFKA_API_KEY, SERVICE_ACCOUNT
- Importance: high
kafka.api.key
Kafka API Key. Required when kafka.auth.mode==KAFKA_API_KEY.
- Type: password
- Importance: high
kafka.service.account.id
The Service Account that will be used to generate the API keys to communicate with Kafka Cluster.
- Type: string
- Importance: high
kafka.api.secret
Secret associated with Kafka API key. Required when kafka.auth.mode==KAFKA_API_KEY.
- Type: password
- Importance: high
GCP credentials¶
gcp.spanner.credentials.json
GCP service account JSON file with write permissions for Spanner.
- Type: password
- Importance: high
How should we connect to your Spanner?¶
gcp.spanner.instance.id
The ID of the Spanner instance to connect to.
- Type: string
- Importance: high
gcp.spanner.database.id
Database ID where tables are located or will be created.
- Type: string
- Importance: high
Database details¶
insert.mode
The insertion mode to use.
- Type: string
- Default: INSERT
- Importance: high
table.name.format
A format string for the destination table name, which may contain ${topic} as a placeholder for the originating topic name.
For example, kafka_${topic} for the topic ‘orders’ will map to the table name ‘kafka_orders’.
Spanner constraints for table names are {a—z|A—Z}[{a—z|A—Z|0—9|_}+].
- Type: string
- Default: ${topic}
- Importance: medium
Primary Key¶
pk.mode
The primary key mode, also refer to pk.fields documentation for interplay. Supported modes are:
none: No keys utilized.
kafka: Apache Kafka® coordinates are used as the PK.
record_value: Field(s) from the record value are used, which must be a struct.
- Type: string
- Importance: high
pk.fields
List of comma-separated primary key field names. The runtime interpretation of this config depends on the pk.mode:
none: Ignored as no fields are used as primary key in this mode.kafka: Must be a trio representing the Kafka coordinates, defaults to __connect_topic,__connect_partition,__connect_offset if empty.
record_value: If empty, all fields from the value struct will be used, otherwise used to extract the desired fields.
- Type: list
- Importance: high
SQL/DDL Support¶
auto.create
Whether to automatically create the destination table if it is missing.
- Type: boolean
- Default: false
- Importance: medium
auto.evolve
Whether to automatically add columns in the table if they are
- Type: boolean
- Default: false
- Importance: medium
Connection details¶
max.batch.size
The maximum number of records that can be batched into a single insert, or upsert to Spanner.
- Type: int
- Default: 1000
- Valid Values: [1,…,5000]
- Importance: medium
Consumer configuration¶
max.poll.interval.ms
The maximum delay between subsequent consume requests to Kafka. This configuration property may be used to improve the performance of the connector, if the connector cannot send records to the sink system. Defaults to 300000 milliseconds (5 minutes).
- Type: long
- Default: 300000 (5 minutes)
- Valid Values: [60000,…,1800000] for non-dedicated clusters and [60000,…] for dedicated clusters
- Importance: low
max.poll.records
The maximum number of records to consume from Kafka in a single request. This configuration property may be used to improve the performance of the connector, if the connector cannot send records to the sink system. Defaults to 500 records.
- Type: long
- Default: 500
- Valid Values: [1,…,500] for non-dedicated clusters and [1,…] for dedicated clusters
- Importance: low
Number of tasks for this connector¶
tasks.max
Maximum number of tasks for the connector.
- Type: int
- Valid Values: [1,…]
- Importance: high
Auto-restart policy¶
auto.restart.on.user.error
Enable connector to automatically restart on user-actionable errors.
- Type: boolean
- Default: true
- Importance: medium
Additional Configs¶
consumer.override.auto.offset.reset
Defines the behavior of the consumer when there is no committed position (which occurs when the group is first initialized) or when an offset is out of range. You can choose either to reset the position to the “earliest” offset or the “latest” offset (the default). You can also select “none” if you would rather set the initial offset yourself and you are willing to handle out of range errors manually. More details: https://docs.confluent.io/platform/current/installation/configuration/consumer-configs.html#auto-offset-reset
- Type: string
- Importance: low
consumer.override.isolation.level
Controls how to read messages written transactionally. If set to read_committed, consumer.poll() will only return transactional messages which have been committed. If set to read_uncommitted (the default), consumer.poll() will return all messages, even transactional messages which have been aborted. Non-transactional messages will be returned unconditionally in either mode. More details: https://docs.confluent.io/platform/current/installation/configuration/consumer-configs.html#isolation-level
- Type: string
- Importance: low
header.converter
The converter class for the headers. This is used to serialize and deserialize the headers of the messages.
- Type: string
- Importance: low
value.converter.allow.optional.map.keys
Allow optional string map key when converting from Connect Schema to Avro Schema. Applicable for Avro Converters.
- Type: boolean
- Importance: low
value.converter.auto.register.schemas
Specify if the Serializer should attempt to register the Schema.
- Type: boolean
- Importance: low
value.converter.connect.meta.data
Allow the Connect converter to add its metadata to the output schema. Applicable for Avro Converters.
- Type: boolean
- Importance: low
value.converter.enhanced.avro.schema.support
Enable enhanced schema support to preserve package information and Enums. Applicable for Avro Converters.
- Type: boolean
- Importance: low
value.converter.enhanced.protobuf.schema.support
Enable enhanced schema support to preserve package information. Applicable for Protobuf Converters.
- Type: boolean
- Importance: low
value.converter.flatten.unions
Whether to flatten unions (oneofs). Applicable for Protobuf Converters.
- Type: boolean
- Importance: low
value.converter.generate.index.for.unions
Whether to generate an index suffix for unions. Applicable for Protobuf Converters.
- Type: boolean
- Importance: low
value.converter.generate.struct.for.nulls
Whether to generate a struct variable for null values. Applicable for Protobuf Converters.
- Type: boolean
- Importance: low
value.converter.int.for.enums
Whether to represent enums as integers. Applicable for Protobuf Converters.
- Type: boolean
- Importance: low
value.converter.latest.compatibility.strict
Verify latest subject version is backward compatible when use.latest.version is true.
- Type: boolean
- Importance: low
value.converter.object.additional.properties
Whether to allow additional properties for object schemas. Applicable for JSON_SR Converters.
- Type: boolean
- Importance: low
value.converter.optional.for.nullables
Whether nullable fields should be specified with an optional label. Applicable for Protobuf Converters.
- Type: boolean
- Importance: low
value.converter.optional.for.proto2
Whether proto2 optionals are supported. Applicable for Protobuf Converters.
- Type: boolean
- Importance: low
value.converter.use.latest.version
Use latest version of schema in subject for serialization when auto.register.schemas is false.
- Type: boolean
- Importance: low
value.converter.use.optional.for.nonrequired
Whether to set non-required properties to be optional. Applicable for JSON_SR Converters.
- Type: boolean
- Importance: low
value.converter.wrapper.for.nullables
Whether nullable fields should use primitive wrapper messages. Applicable for Protobuf Converters.
- Type: boolean
- Importance: low
value.converter.wrapper.for.raw.primitives
Whether a wrapper message should be interpreted as a raw primitive at root level. Applicable for Protobuf Converters.
- Type: boolean
- Importance: low
key.converter.key.subject.name.strategy
How to construct the subject name for key schema registration.
- Type: string
- Default: TopicNameStrategy
- Importance: low
value.converter.decimal.format
Specify the JSON/JSON_SR serialization format for Connect DECIMAL logical type values with two allowed literals:
BASE64 to serialize DECIMAL logical types as base64 encoded binary data and
NUMERIC to serialize Connect DECIMAL logical type values in JSON/JSON_SR as a number representing the decimal value.
- Type: string
- Default: BASE64
- Importance: low
value.converter.flatten.singleton.unions
Whether to flatten singleton unions. Applicable for Avro and JSON_SR Converters.
- Type: boolean
- Default: false
- Importance: low
value.converter.reference.subject.name.strategy
Set the subject reference name strategy for value. Valid entries are DefaultReferenceSubjectNameStrategy or QualifiedReferenceSubjectNameStrategy. Note that the subject reference name strategy can be selected only for PROTOBUF format with the default strategy being DefaultReferenceSubjectNameStrategy.
- Type: string
- Default: DefaultReferenceSubjectNameStrategy
- Importance: low
value.converter.value.subject.name.strategy
Determines how to construct the subject name under which the value schema is registered with Schema Registry.
- Type: string
- Default: TopicNameStrategy
- Importance: low
Next Steps¶
For an example that shows fully-managed Confluent Cloud connectors in action with Confluent Cloud ksqlDB, see the Cloud ETL Demo. This example also shows how to use Confluent CLI to manage your resources in Confluent Cloud.