8.5. Logging

In this chapter, you’ll learn how to use Local Protocol’s logging utility.

Logger Class#

Local Protocol provides a Logger class with advanced logging functionalities. This includes configuring logging levels or saving logs to a file.

The Local Protocol application registers the Logger class in the Local Protocol container and each module's container as logger.

How to Log a Message#

Resolve the logger using the Local Protocol container to log a message in your resource.

For example, create the file src/jobs/log-message.ts with the following content:

src/jobs/log-message.ts
1import { LocalProtoContainer } from "@localprotojs/framework/types"2import { ContainerRegistrationKeys } from "@localprotojs/framework/utils"3
4export default async function myCustomJob(5  container: LocalProtoContainer6) {7  const logger = container.resolve(ContainerRegistrationKeys.LOGGER)8
9  logger.info("I'm using the logger!")10}11
12export const config = {13  name: "test-logger",14  // execute every minute15  schedule: "* * * * *",16}

This creates a scheduled job that resolves the logger from the Local Protocol container and uses it to log a message.

Test the Scheduled Job#

To test out the above scheduled job, start the Local Protocol application:

npm
yarn
pnpm

After a minute, you'll see the following message as part of the logged messages:

Code
info:    I'm using the logger!

Log Levels#

The Logger class has the following methods:

• info: The message is logged with level info.
• warn: The message is logged with level warn.
• error: The message is logged with level error.
• debug: The message is logged with level debug.

Each of these methods accepts a string parameter to log in the terminal with the associated level.

Logging Configurations#

Log Level#

The available log levels, from lowest to highest levels, are:

1. silly (default, meaning messages of all levels are logged)
2. debug
3. info
4. warn
5. error

You can change that by setting the LOG_LEVEL environment variable to the minimum level you want to be logged.

For example:

Terminal
❯LOG_LEVEL=error

This logs error messages only.

Save Logs in a File#

Aside from showing the logs in the terminal, you can save the logs in a file by setting the LOG_FILE environment variable to the path of the file relative to the Local Protocol server’s root directory.

For example:

Terminal
❯LOG_FILE=all.log

Your logs are now saved in the all.log file at the root of your Local Protocol application.

Show Log with Progress#

The Logger class has an activity method used to log a message of level info. If the Local Protocol application is running in a development environment, a spinner starts to show the activity's progress.

For example:

src/jobs/log-message.ts
1import { LocalProtoContainer } from "@localprotojs/framework/types"2import { ContainerRegistrationKeys } from "@localprotojs/framework/utils"3
4export default async function myCustomJob(5  container: LocalProtoContainer6) {7  const logger = container.resolve(ContainerRegistrationKeys.LOGGER)8
9  const activityId = logger.activity("First log message")10
11  logger.progress(activityId, `Second log message`)12
13  logger.success(activityId, "Last log message")14}

The activity method returns the ID of the started activity. This ID can then be passed to one of the following methods of the Logger class:

• progress: Log a message of level info that indicates progress within that same activity.
• success: Log a message of level info that indicates that the activity has succeeded. This also ends the associated activity.
• failure: Log a message of level error that indicates that the activity has failed. This also ends the associated activity.