The Cement Basic Module

Angstone Cement Basic Module

Environment constants, a logger and an error handler acting as TypeScript boilerplate

contains:

• env
• logger (with chalk)
• error (good dealer)
• signature

install

npm install @angstone/cement-basic

use

import {
  signature,
  logger,
  error,
  ENVS,
  LOGLEVELS
} from '@angstone/cement-basic'

// Set environment variables

process.env.APP_ENV = ENVS.DEV // or ENVS.PROD
process.env.APP_LOGLEVEL = LOGLEVELS.DEV_NOTE // or other

// call your app signature
signature()

// be happy and enjoy! :)

logger.note('This app is amazing, lets code it!')
logger.dev('That is the result of the date.now(): ', Date.now())
logger.fatal('This is very bad! :(')
logger.error('This is a expected common error :/')

let myError: Error
myError = error.is(
  'this specific one error',
  'and contains',
  { several: 'details' }
)
// it uses new Error(..) internally

error.op('operational expected error') // prints if LOGLEVELS allows
error.op(new Error())
error.op(myError)

/*
* terminates the application if APP_ENV is set to
* ENVS.PROD ('prod')
*/
error.fatal('really bad error')
error.fatal(new Error())
error.fatal(myError)

error.throw('Error that I wont deal with now, but upstairs in code')
error.throw(new Error('any type that extends Error'))
error.throw(myError)

// Practical sample:

logger.note('Doing Stuff')
await someNiceAndCleanAsyncTask.catch(error.throw)
await otherGoodTask.catch(error.op) // that doesn't matter a lot
logger.dev('Hey devs, pay attention on this task:')
await importantTask.catch(error.fatal) // a failure here restart app

env

The env define default environment variables.

Always use process.env.APP_{YOUR ENV VARIABLE}

Exports process.env as env

logger

The logger wraps your way of handling your logs. Exposes 4 functions from interface ILogger. Comes with a default implementation called defaultLogger witch just prints in the console.

• fatal(...any): for red fatal errors
• error(...any): for yellow operational errors
• note(...any): for blue execution notes
• dev(...any): for bright purple dev notes

Each ones prints the console only if the APP_LOGLEVEL environment variable allows your kind. They are:

LOGLELEVELS.FATAL LOGLELEVELS.ERROR LOGLELEVELS.NOTE LOGLELEVELS.DEV_NOTE

exports the default implementation and the function useLogger to setup yours

error

The error wraps your way of handling your errors. Exposes 4 functions from interface IError.

Comes with a default implementation called defaultError witch just log errors and also (gracefully?) stops application in case of fatal error.

• is(message, details): create a default AppError
• op(message|Error, details): handle operational error
• fatal(message|Error, details): handle fatal error also (gracefully?) stops application if APP_ENV is set to ENVS.PROD
• throw(message|Error, details): throw an error upstairs in code

They use logger.fatal for fatal and logger.error for operational

exports the default implementation and the function useError to setup yours

signature

You use this by importing and running the signature() function in the beginning of your code, after setup of you environment variables.

It prints a friendly review of your package.json and register the environment variable APP_LOADED_AT in milliseconds.

You NEED this to make sure env, logger, and error modules are going to work as default expected.

Indeed, THIS IS A BOILERPLATE, that is also a real-world-case-in-use-by-me-right-now useful npm module.

Act as TypeScript Node Boilerplate for cement framework

Features:

• tslint
• prettier
• tslint-config-prettier
• typescript
• ts-node
• nodemon
• mocha
• chai
• chai-like
• chai-things
• sinon
• sinon-chai
• nyc (coverage)
• source-map-support (for use with coverage)
• supertest
• request
• request-promise-native
• express
• cors
• wallaby
• cron
• chalk
• Docker's Composition