handleDataRequestWithCanaryTraffic.ts

const CANARY_THRESHOLD_PERCENT = parseInt(
  process.env.CANARY_THRESHOLD_PERCENT || '0',
);

/**
 * This function divides the traffic between Old Data API and New Data API
 * based on the runtime configuration of CANARY_THRESHOLD_PERCENT.
 */
export const handleDataRequestWithCanaryTraffic = (
  requestId: string,
  animal: TAnimal,
): Promise<TDataApiData> => {
  const randomValue = randomThresholdValue();
  console.log(
    `requestId: ${requestId} – DEBUG: random value = ${randomValue}, CANARY_THRESHOLD_PERCENT = ${CANARY_THRESHOLD_PERCENT}`,
  );

  if (CANARY_THRESHOLD_PERCENT > randomValue) {
    /**
     * If CANARY_THRESHOLD_PERCENT is higher than the random value (0-99), make
     * the request to New Data API. Therefore if CANARY_THRESHOLD_PERCENT === 100,
     * all request are made to New Data API.
     */
    return newDataApiClient.getData(requestId, animal);
  } else {
    /**
     * If CANARY_THRESHOLD_PERCENT is lower than or equal to the random value (0-99),
     * make the request to Old Data API. Therefore if CANARY_THRESHOLD_PERCENT === 0,
     * all request are made to Old Data API.
     */
    return oldDataApiClient.getData(requestId, animal);
  }
};