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Logger

Overview​

The logger.js file sets up a logging system using the pino library. It configures two transports: one for logging to the console and another for sending logs to a Grafana Loki instance. This allows for both local development logging and centralized logging in a production environment.

Dependencies​

  • pino: A fast and lightweight logger for Node.js.
  • pino-http: A logger for HTTP requests.
  • node:crypto: Used to generate random UUIDs for request IDs.

Configuration​

The logger is configured using the following environment variables:

  • GRAFANA_USERNAME: The username for authenticating with Grafana Loki.
  • GRAFANA_PASSWORD: The password for authenticating with Grafana Loki.
  • APP_NAME: The name of the application, used as a label in Loki.
  • NODE_ENV: The environment (e.g., development, production), used as a label in Loki.
  • GRAFANA_LOGS_HOST: The host of the Grafana Loki instance.

Transports​

The logger is configured with two transports:

  1. File Transport: Logs to standard output (the console).
  2. Pino Loki Transport: Sends logs to a Grafana Loki instance. It batches logs and sends them every second. The logs are labeled with the app name and environment.

Logger Instance​

A pino logger instance is created with the configured transports.

Request/Response Logger​

A pino-http logger is also created to log HTTP requests and responses. It generates a unique request ID for each request, which is also added to the response headers as X-Request-Id.

Exports​

  • logger: The main pino logger instance.
  • reqResLogger: The pino-http logger for logging requests and responses.