# @openstapps/logger

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This is a simple logger for TypeScript projects with transformations for the log output.

Logs are only printed if their log level is equal or higher than the defined log level.

## Log Levels

Available log levels are:
- 1 - INFO
- 2 - LOG
- 4 - WARN
- 8 - ERROR
- 16 - OK

You can set your log level with the environment variable `STAPPS_LOG_LEVEL`.

To select your desired log levels add the corresponding numbers and set the value of `STAPPS_LOG_LEVEL` to the sum.

For example `STAPPS_LOG_LEVEL=17` is 16 + 1 and would log everything that is `OK` or `INFO`.

If you want to use logger in production (`NODE_ENV=production`) and allow all transports to fail set
`ALLOW_NO_TRANSPORT` to `true`.

Additionally setting the environment variable `STAPPS_EXIT_LEVEL` which works in the same manner as `STAPPS_LOG_LEVEL` will terminate your process after logging at the selected level(s) (usefull for integration tests). It will be ignored in afore mentioned productive environments.

## SMTP

This class also provides a simple implementation of an SMTP transport which can be used as a
`TransportWithVerification` for the logger. You can use this to transport errors of the logger or to transport mails
of your own monitoring solution.

### Usage

You can instatiate it with a config or it will check for a config in the environment variables. Environment variables
can overwrite the actual config values.

Environment variables are:

* SMTP_AUTH_USER:      SMTP username
* SMTP_AUTH_PASSWORD:  SMTP password
* SMTP_HOST:           SMTP host
* SMTP_PORT:           SMTP port
* SMTP_RECIPIENTS:     comma seperated list of recipients
* SMTP_CC:             comma seperated list of recipients for the carbon copy (CC)
* SMTP_SENDER_MAIL:    sender of the mail
* SMTP_SENDER_NAME:    name of the sender
* SMTP_SECURE:         `true` to enable tls

## Transformations

By default the logger will only add the log level to the message.

You can change this behavior by setting other Transformers via `Logger.setTransformations`. If you do so, mind the order of the transformers.

You may choose from the following:

* `AddLogLevel`, which prepends the output with the log level
* `Colorize`, which colorizes the output according to the log level
* `Timestamp`, which prepends a timestamp to the output