balancereader

Balance Reader Service

The balance reader service provides an efficient readable cache of user balances, as read from the ledger-db.

The ledger-db service holds the source of truth for the system. The balance-reader reads and caches data from the ledger-db, but may be out of date when under heavy load.

Implemented in Java with Spring Boot and Guava.

Endpoints

Endpoint	Type	Auth?	Description
/balances/<accountid>	GET	🔒	Get the account balance iff owned by the currently authenticated user.
/healthy	GET		Liveness probe endpoint. Monitors health of background thread.
/ready	GET		Readiness probe endpoint.
/version	GET		Returns the contents of $VERSION

Environment Variables

• VERSION

  • a version string for the service

• PORT

  • the port for the webserver

• POLL_MS

  • the number of milliseconds to wait in between polls to ledger-db
  • optional. Defaults to 100

• CACHE_SIZE

  • the max number of account balances to store in the cache
  • optional. Defaults to 1,000,000

• JVM_OPTS

  • settings for the JVM. Used to obey container memory limits

• LOG_LEVEL

  • service level log level

• ConfigMap environment-config:

  • LOCAL_ROUTING_NUM
    • the routing number for our bank
  • PUB_KEY_PATH
    • the path to the JWT signer's public key, mounted as a secret

• ConfigMap ledger-db-config:

  • SPRING_DATASOURCE_URL
    • URL of the ledger-db service
  • SPRING_DATASOURCE_USERNAME
    • username for the ledger-db database
  • SPRING_DATASOURCE_PASSWORD
    • password for the ledger-db database

Kubernetes Resources

• deployments/balancereader
• service/balancereader