Prepare Spanner for RDI
Prepare Google Cloud Spanner databases to work with RDI
Google Cloud Spanner requires specific configuration to enable change data capture (CDC) with RDI. RDI operates in two phases with Spanner: snapshot (initial sync) and streaming. During the snapshot phase, RDI uses the JDBC driver to connect directly to Spanner and read the current state of the database. In the streaming phase, RDI uses Spanner's Change Streams to capture changes related to the monitored schemas and tables.
1. Prepare for snapshot
During the snapshot phase, RDI executes multiple transactions to capture data at an exact point in time that remains consistent across all queries. This is achieved using a Spanner feature called Timestamp bounds with exact staleness.
This feature relies on the version_retention_period, which is set to one hour by default. Depending on the database tier, the volume of data to be ingested into RDI, and the load on the database, this setting may need to be increased. You can update it using this method.
2. Prepare for streaming
To enable streaming, you must create a change stream in Spanner at the database level. Use the
option value_capture_type = 'NEW_ROW_AND_OLD_VALUES'
to capture both the previous and updated
row values.
Be sure to specify only the tables you want to ingest from and, optionally, the specific columns you're interested in. Here's an example using Google SQL syntax:
CREATE CHANGE STREAM change_stream_table1_and_table2
FOR table1, table2
OPTIONS (
value_capture_type = 'NEW_ROW_AND_OLD_VALUES'
);
Refer to the official documentation for more details, including additional configuration options and dialect-specific syntax.
3. Create a service account
To allow RDI to access the Spanner instance, you'll need to create a service account with the appropriate permissions. This service account will then be provided to RDI as a secret for authentication.
-
Create the service account
gcloud iam service-accounts create spanner-reader-account \ --display-name="Spanner Reader Service Account" \ --description="Service account for reading from Spanner databases" \ --project=YOUR_PROJECT_ID
-
Grant required roles
Database Reader (read access to Spanner data):
gcloud projects add-iam-policy-binding YOUR_PROJECT_ID \ --member="serviceAccount:spanner-reader-account@YOUR_PROJECT_ID.iam.gserviceaccount.com" \ --role="roles/spanner.databaseReader"
Database User (query execution and metadata access):
gcloud projects add-iam-policy-binding YOUR_PROJECT_ID \ --member="serviceAccount:spanner-reader-account@YOUR_PROJECT_ID.iam.gserviceaccount.com" \ --role="roles/spanner.databaseUser"
Viewer (viewing instance and database configuration):
gcloud projects add-iam-policy-binding YOUR_PROJECT_ID \ --member="serviceAccount:spanner-reader-account@YOUR_PROJECT_ID.iam.gserviceaccount.com" \ --role="roles/spanner.viewer"
-
Download the service account key
Save the credentials locally so they can be used later by RDI:
gcloud iam service-accounts keys create ~/spanner-reader-account.json \ --iam-account=spanner-reader-account@YOUR_PROJECT_ID.iam.gserviceaccount.com \ --project=YOUR_PROJECT_ID
4. Set up secrets for Kubernetes deployment
Before deploying the RDI pipeline, you need to configure the necessary secrets for both the source and target databases. Instructions for setting up the target database secrets are available in the RDI deployment guide.
In addition to the target database secrets, you'll also need to create a Spanner-specific secret
named source-db-credentials
. This secret should contain the service account key file generated
during the Spanner setup phase. Use the command below to create it:
kubectl create secret generic source-db-credentials --namespace=rdi \
--from-file=gcp-service-account.json=~/spanner-reader-account.json \
--save-config --dry-run=client -o yaml | kubectl apply -f -
Be sure to adjust the file path (~/spanner-reader-account.json
) if your service account key is
stored elsewhere.
5. Configure RDI for Spanner
When configuring your RDI pipeline for Spanner, use the following example configuration in your
config.yaml
file:
sources:
source:
type: flink
connection:
type: spanner
project_id: your-project-id
instance_id: your-spanner-instance
database_id: your-spanner-database
change_streams:
change_stream_all:
{}
# retention_hours: 24
# schemas:
# - DEFAULT
# tables:
# products: {}
# orders: {}
# order_items: {}
# logging:
# level: debug
# advanced:
# source:
# spanner.change.stream.retention.hours: 24
# spanner.fetch.timeout.milliseconds: 20000
# spanner.dialect: POSTGRESQL
# flink:
# jobmanager.rpc.port: 7123
# jobmanager.memory.process.size: 1024m
# taskmanager.numberOfTaskSlots: 3
# taskmanager.rpc.port: 7122
# taskmanager.memory.process.size: 2g
# blob.server.port: 7124
# rest.port: 8082
# parallelism.default: 4
# restart-strategy.type: fixed-delay
# restart-strategy.fixed-delay.attempts: 3
targets:
target:
connection:
type: redis
host: ${HOST_IP}
port: 12000
user: ${TARGET_DB_USERNAME}
password: ${TARGET_DB_PASSWORD}
processors:
target_data_type: hash
Make sure to replace the relevant connection details with your own for both the Spanner and target Redis databases.
6. Additional Kubernetes configuration
In your rdi-values.yaml
file for Kubernetes deployment, make sure to configure the dataPlane
section like this:
operator:
dataPlane:
flinkCollector:
enabled: true
jobManager:
ingress:
enabled: true
className: traefik # Replace with your ingress controller
hosts:
- hostname # Replace with your desired ingress hostname
7. Configuration is complete
Once you have followed the steps above, your Google Spanner database is ready for RDI to use.