Logging in Booster

If no configuration is provided, Booster uses the default JavaScript logging capabilities. Depending on the log level, it will call different logging methods:

• console.debug for Level.debug
• console.info for Level.info
• console.warn for Level.warn
• console.error for Level.error

In this regard, there's no distinction from any other node process and you'll find the logs in your cloud provider's default log aggregator (i.e. Cloudwatch if you use AWS).

Advanced logging

You may need some advanced logging capabilities, such as redirecting your logs to a log aggregator. Booster also supports overriding the default behavior by providing custom loggers. The only thing you need to do is to provide an object that implements the Logger interface at config time:

@boostercloud/framework-types/lib/logger.ts

interface Logger {
  debug(message?: any, ...optionalParams: any[]): void
  info(message?: any, ...optionalParams: any[]): void
  warn(message?: any, ...optionalParams: any[]): void
  error(message?: any, ...optionalParams: any[]): void
}

src/config/config.ts

Booster.configure('development', (config: BoosterConfig): void => {
  config.appName = 'my-store'
  config.providerPackage = '@boostercloud/framework-provider-aws'
  config.logger = new MyCustomLogger() // Overrides the default logger object
  config.logLevel = Level.debug        // Sets the log level at 'debug'     
  config.logPrefix = 'my-store-dev'    // Sets the default prefix
})

Using the Booster's logger

All framework's components will use this logger by default and will generate logs that match the following pattern:

[<logPrefix>]|moduleName: <message>

You can get a custom logger instance that extends the configured logger by adding your moduleName and optionally overriding the configured prefix with the getLogger helper function. It's a good practice to build and use a separate logger instance built with this method for each context, as this will make it easier to filter your logs when you need to investigate a problem.

Example: Obtaining a logger for your command:

@Command({
  authorize: [User],
})
export class UpdateShippingAddress {
  public constructor(readonly cartId: UUID, readonly address: Address) {}

  public static async handle(command: UpdateShippingAddress, register: Register): Promise<void> {
    const logger = getLogger(Booster.config, 'UpdateShippingCommand#handler', 'MyApp')
    logger.debug(`User ${register.currentUser?.username} changed shipping address for cart ${command.cartId}: ${JSON.stringify(command.address}`)
    register.events(new ShippingAddressUpdated(command.cartId, command.address))
  }
}

When a UpdateShippingAddress command is handled, it wil log messages that look like the following:

[MyApp]|UpdateShippingCommand#handler: User buyer42 changed shipping address for cart 314: { street: '13th rue del percebe', number: 6, ... }

info

Using the configured Booster logger is not mandatory for your application, but it might be convenient to centralize your logs and this is a standard way to do it.