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Node.js Service Tools

Prepare your Node.js application for production!

This library provides common functionalities, like graceful error handling & shutdown, structured JSON logging and several HTTP middleware to make your application truly ready for modern containerised environments, like Kubernetes.

Installation

npm i @banzaicloud/service-tools
# or
yarn add @banzaicloud/service-tools

Usage & Examples

This library is written in TypeScript, refer to the published types or the source code for argument and return types.

Examples are available for Express and Koa frameworks. Check out the examples folder!

Main exports

catchErrors(options)

Catch uncaught exceptions and unhandled Promise rejections. It is not safe to resume normal operation after 'uncaughtException'.

const { catchErrors } = require('@banzaicloud/service-tools')

// ...

// the handlers return a Promise
// the handlers are called in order
catchErrors([closeServer, closeDB])

// the error will be caught and the handlers will be called before exiting
throw new Error()

gracefulShutdown(handlers, options)

Graceful shutdown: release resources (databases, HTTP connections, ...) before exiting. When the application receives SIGTERM or SIGINT signals, the close handlers will be called. The handlers should return a Promise.

const { gracefulShutdown } = require('@banzaicloud/service-tools')

// ...

// the handlers return a Promise
// the handlers are called in order
gracefulShutdown([closeServer, closeDB])

logger

A pino structured JSON logger instance configured with config.pino.

const { logger } = require('@banzaicloud/service-tools')

logger.info({ metadata: true }, 'log message')
// > {"level":30,"time":<ts>,"msg":"log message","pid":0,"hostname":"local","metadata":true,"v":1}
Use provided logger instead of console

Globally overwrite the console and use the logger provided by the library to print out messages.

const { logger } = require('@banzaicloud/service-tools')

console.log('log message')
// > log message

logger.interceptConsole()

console.log('log message')
// > {"level":30,"time":<ts>,"msg":"log message","pid":0,"hostname":"local","v":1}

Config

Load configurations dynamically.

config.environment

Uses the NODE_ENV environment variable, with accepted values of: production, development, test.

const { config } = require('@banzaicloud/service-tools')
// validates the NODE_ENV environment variable
console.log(config.environment)
// > { nodeEnv: 'production' }

config.pino

Used by the provided logger. Uses the LOGGER_LEVEL and LOGGER_REDACT_FIELDS environment variables. The LOGGER_LEVEL can be one of the following: fatal, error, warn, info, debug, trace. LOGGER_REDACT_FIELDS is a comma separated list of field names to mask out in the output (defaults to: 'password, pass, authorization, auth, cookie, _object').

const pino = require('pino')
const { config } = require('@banzaicloud/service-tools')

const logger = pino(config.pino)

logger.info({ metadata: true, password: 'secret' }, 'log message')
// > {"level":30,"time":<ts>,"msg":"log message","pid":0,"hostname":"local","metadata":true,"password":"[REDACTED]","v":1}

Middleware (Koa)

Several middleware for the Koa web framework.

errorHandler(options)

Koa error handler middleware.

const Koa = require('koa')
const { koa: middleware } = require('@banzaicloud/service-tools').middleware

const app = new Koa()

// this should be the first middleware
app.use(middleware.errorHandler())

healthCheck(checks, options)

Koa health check endpoint handler.

const Koa = require('koa')
const Router = require('koa-router')
const { koa: middleware } = require('@banzaicloud/service-tools').middleware

// ...

const app = new Koa()
const router = new Router()

// the checks return a Promise
router.get('/health', middleware.healthCheck([checkDB]))

app.use(router.routes())
app.use(router.allowedMethods())

prometheusMetrics(options)

Koa Prometheus metrics endpoint handler. By default it collects some default metrics.

const Koa = require('koa')
const Router = require('koa-router')
const { koa: middleware } = require('@banzaicloud/service-tools').middleware

// ...

const app = new Koa()
const router = new Router()

router.get('/metrics', middleware.prometheusMetrics())

app.use(router.routes())
app.use(router.allowedMethods())

requestValidator(options)

Koa request validator middleware. Accepts Joi schemas for body (body parser required), params and query (query parser required). Returns with 400 if the request is not valid. Assigns validated values to ctx.state.validated.

const joi = require('joi')
const qs = require('qs')
const Koa = require('koa')
const Router = require('koa-router')
const bodyParser = require('koa-bodyparser')
const { koa: middleware } = require('@banzaicloud/service-tools').middleware

// ...

const app = new Koa()
const router = new Router()

const paramsSchema = joi
  .object({
    id: joi
      .string()
      .hex()
      .length(64)
      .required(),
  })
  .required()

const bodySchema = joi.object({ name: joi.string().required() }).required()

const querySchema = joi.object({ include: joi.array().default([]) }).required()

router.get(
  '/',
  middleware.requestValidator({ params: paramsSchema, body: bodySchema, query: querySchema }),
  async function routeHandler(ctx) {
    const { params, body, query } = ctx.state.validated
    // ...
  }
)

app.use(bodyParser())
// query parser
app.use(async function parseQuery(ctx, next) {
  ctx.query = qs.parse(ctx.querystring, options)
  ctx.request.query = ctx.query
  await next()
})
app.use(router.routes())
app.use(router.allowedMethods())

requestLogger(options)

Koa request logger middleware. Useful for local development and debugging.

const Koa = require('koa')
const { koa: middleware } = require('@banzaicloud/service-tools').middleware

// ...

const app = new Koa()

// this should be the second middleware after the error handler
// ...
app.use(middleware.requestLogger())

Middleware (Express)

Several middleware for the Express web framework.

errorHandler(options)

Express error handler middleware.

const express = require('express')
const { express: middleware } = require('@banzaicloud/service-tools').middleware

const app = express()

// this should be the last middleware
app.use(middleware.errorHandler())

healthCheck(checks, options)

Express health check endpoint handler.

const express = require('express')
const { express: middleware } = require('@banzaicloud/service-tools').middleware

// ...

const app = express()

// the checks return a Promise
app.get('/health', middleware.healthCheck([checkDB]))

prometheusMetrics(options)

Express Prometheus metrics endpoint handler. By default it collects some default metrics.

const express = require('express')
const { express: middleware } = require('@banzaicloud/service-tools').middleware

// ...

const app = express()

app.get('/metrics', middleware.prometheusMetrics())

requestValidator(options)

Express request validator middleware. Accepts Joi schemas for body (body parser required), params and query. Returns with 400 if the request is not valid. Assigns validated values to req.

const joi = require('joi')
const express = require('express')
const { express: middleware } = require('@banzaicloud/service-tools').middleware

// ...

const app = express()

const paramsSchema = joi
  .object({
    id: joi
      .string()
      .hex()
      .length(64)
      .required(),
  })
  .required()

const bodySchema = joi.object({ name: joi.string().required() }).required()

const querySchema = joi.object({ include: joi.array().default([]) }).required()

app.use(express.json())
app.get(
  '/',
  middleware.requestValidator({ params: paramsSchema, body: bodySchema, query: querySchema }),
  function routeHandler(req, res) {
    const { params, body, query } = req
    // ...
  }
)