Loglayer-Effect provides a seamless integration of loglayer, an intuitive logging library with the Effect ecosystem. It enables structured, context-aware logging within your Effect applications by providing a LoggingContext service through Effect's Context.Tag. This allows you to easily manage and configure different logging transports.

const logger = await Effect.runPromise(
  Effect.provide(
    Effect.gen(function* () {
      const logging = yield* LoggingContext;
      return yield* logging.logger;
    }),
    Context.empty().pipe(withStructuredLogging({ prefix: "INFO" })),
  ),
);

To use Loglayer-Effect, you first need to create a logging layer using the withStructuredLogging function. This function returns a LoggingContext service as an Effect Layer. You can then provide this layer to your Effect program.

import { Effect, Context } from "effect";
import { LoggingContext, withStructuredLogging } from "@levicape/loglayer-effect";

const loggingLayer = withStructuredLogging({ prefix: "MyAwesomeApp" });

// 2. Create an Effect that uses the logger
const program = Effect.gen(function* () {
  const logging = yield* LoggingContext;
  const logger = yield* logging.logger;

  logger.info("This is an informational message.");
  logger.error("This is an error message.", { error: new Error("Something went wrong!") });
});

// 3. Provide the layer to your program
const runnable = Effect.provide(program, loggingLayer);

// 4. Run the program
Effect.runPromise(runnable);

withStructuredLogging has the following options:

type LoggingContextOptions = {
  readonly prefix: string;
  readonly context?: Record<string, unknown>;
};

LoggingContext is configured with the following environment variables

• LoggingConfig
  • STRUCTURED_LOGGING: Structured logger to use.
    • pino*
    • consola
    • AWS Powertools
  • LOG_LEVEL: Number representing the log level. 0 is the least verbose, 5 is the most verbose.
  • CI: LoggingContext will enable debug logging when this variable is not blank.
• LoggingConfigAws
  • AWS_LAMBDA_FUNCTION_NAME: Lambda handler name. Configured by AWS Lambda environment automatically. LoggingContext configures the awspowertools logger if set, regardless of STRUCTURED_LOGGING configuration.
    • see https://docs.aws.amazon.com/lambda/latest/dg/configuration-envvars.html
  • AWS_CLOUDMAP_SERVICE_NAME: AWS Cloud Map service. Enables X-Ray Tracing functionality.

• Enhances logs with the current unix timestamp in the unixtime property