@idio/core

@idio/core is a Koa2-based web server with some pre-installed middleware which facilitates quick creation of a web server with the essential functionality, such as serving static files, compression, body parsing, etc. It also provides full JSDoc documentation of all options for completion in IDEs. Other components such as @idio/database, @idio/route and @idio/jsx allow to build more complex websites (to come).

yarn add -E @idio/core

Table Of Contents

• Table Of Contents
• API
• async core(middlewareConfig?: MiddlewareConfig, config?: Config): IdioCore
  • MiddlewareConfig
  • Config
  • IdioCore
• Middleware Configuration
  • Session
  • File Uploads
  • Cross-Site Request Forgery
  • Parse Body
  • Checking Auth
  • Logging
  • Compression
  • Static Files
  • CORS
  • Frontend
• Custom Middleware
• Router Set-up
• Copyright

API

The package is available by importing its default function:

import idioCore from '@idio/core'

async core(  middlewareConfig?: MiddlewareConfig,  config?: Config,): IdioCore

The @idio/core accepts 2 arguments which are the middleware configuration object and server configuration object. It is possible to start the server without any configuration, however it will do nothing, therefore it is important to add some middleware configuration.

MiddlewareConfig: Middleware configuration for the idio core server.

| Name | Type | Description | | ---------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------- | | session | SessionOptions | session options. | | multer | MulterOptions | multer options. | | csrf | CSRFOptions | csrf options. | | bodyparser | BodyparserOptions | bodyparser options. | | compress | CompressOptions | compress options. | | checkauth | CheckauthOptions | checkauth options. | | logger | LoggerOptions | logger options. | | static | StaticOptions | static options. | | cors | CorsOptions | cors options. | | frontend | FrontendOptions | frontend options. If the option is specified, the middleware always will be used, i.e., no need to pass use: true. |

Config: Server configuration object.

| Name | Type | Description | Default | | ---- | --------------- | -------------------------------------- | --------- | | port | number | The port on which to start the server. | 5000 | | host | string | The host on which to listen. | 0.0.0.0 |

The return type contains the URL, Application and Router instances, and the map of configured middleware, which could then be passed to the router.

import('@goa/koa').Application _goa.Application: An instance of the Koa application.

import('@goa/koa').Middleware _goa.Middleware: An async middleware function.

import('koa-router').Router koa-router.Router: An instance of the Koa router.

import('http').Server http.Server: An instance of the Node's Server class.

IdioCore: An object containing the url and references to the app, router and middleware.

| Name | Type | Description | Default | | ---------- | ----------------------------------------------------------------------------------------------------------------------- | ---------------------------------------------------------------------------------------------------- | ----------------------- | | url | string | The url on which the server is accessible. | http://localhost:5000 | | app | _goa.Application | The Koa application. | - | | router | Router | The koa-router instance. | - | | server | http.Server | The http server instance. | - | | middleware | Object<string, _goa.Middleware> | The map of configured middleware functions which could then be set up to be used on a certain route. | - |

To start the server, the async method needs to be called and passed the middleware and server configuration objects. For example, the following code will start a server which serves static files with enabled compression.

import idioCore from '@idio/core'

const Server = async () => {
  const { url } = await idioCore({
    logger: {
      use: true,
    },
    static: {
      use: true,
      root: 'example/static',
      mount: '/static',
    },
    compress: {
      use: true,
      config: {
        threshold: 1024,
      },
    },
  }, {
    port: 8080,
  })
  console.log('File available at: %s/static/test.txt', url)
}

File available at: http://localhost:8080/static/test.txt

Middleware Configuration

The middleware can be configured according to the MiddlewareConfig. @idio/core comes with some installed middleware as dependencies to speed up the process of creating a web server. Moreover, any custom middleware which is not part of the bundle can also be specified here (see Custom Middleware).

Each middleware accepts the following properties:

| Property | Description | Default | | ---------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------- | | use | Whether to use this middleware for every request. If not set to true, the configured middleware function will be included in the middleware property of the returned object, which can then be passed to a router configuration (not part of the @idio/core). | false | | config | Configuration object expected by the middleware constructor. | {} | | ...props | Any additional specific properties (see individual middleware configuration). | |

SessionOptions

| Name | Type | Description | Default | | --------- | ------------------------------------------------------------------------------------------------------- | -------------------------------------------- | ------- | | keys* | string[] | A set of keys to be installed in app.keys. | - | | use | boolean | Use this middleware for every request. | false | | config | SessionConfig | koa-session configuration. | - |

SessionConfig: Configuration passed to koa-session.

| Name | Type | Description | Default | | --------- | ------------------------------ | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ---------- | | key | string | Cookie key. | koa:sess | | maxAge | (number | 'session') | maxAge in ms with default of 1 day. session will result in a cookie that expires when session/browser is closed. Warning: If a session cookie is stolen, this cookie will never expire. | 86400000 | | overwrite | boolean | Can overwrite or not. | true | | httpOnly | boolean | httpOnly or not. | true | | signed | boolean | Signed or not. | true | | rolling | boolean | Force a session identifier cookie to be set on every response. The expiration is reset to the original maxAge, resetting the expiration countdown. | false | | renew | boolean | Renew session when session is nearly expired, so we can always keep user logged in. | false |

MulterOptions

| Name | Type | Description | Default | | ------ | ------------------------------------------- | -------------------------------------- | ------- | | use | boolean | Use this middleware for every request. | false | | config | MulterConfig | koa-multer configuration. | - |

import('http').IncomingMessage http.IncomingMessage

import('fs').Stats fs.Stats

import('koa-multer').StorageEngine koa-multer.StorageEngine

import('koa-multer').File koa-multer.File

Limits: An object specifying the size limits.

| Name | Type | Description | Default | | ------------- | --------------- | ---------------------------------------------------------------------------- | ---------- | | fieldNameSize | number | Max field name size in bytes. | 100 | | fieldSize | number | Max field value size in bytes. | 1024 | | fields | number | Max number of non-file fields. | Infinity | | fileSize | number | For multipart forms, the max file size in bytes. | Infinity | | files | number | For multipart forms, the max number of file fields. | Infinity | | parts | number | For multipart forms, the max number of parts (fields + files). | Infinity | | headerPairs | number | For multipart forms, the max number of header key=> value pairs to parse. | 2000 |

MulterConfig

| Name | Type | Description | Default | | ------------ | -------------------------------------------------------------------------------------------------------------------------------------- | ----------------------------------------------------------------------------------------------- | ------- | | dest | string | Where to store the files. | - | | storage | StorageEngine | Where to store the files. | - | | fileFilter | (req: IncomingMessage, file: File, callback: (error: (Error|null), acceptFile: boolean)) => void | Function to control which files are accepted. | - | | limits | Limits | Limits of the uploaded data. | - | | preservePath | boolean | Keep the full path of files instead of just the base name. | false |

CSRFOptions

| Name | Type | Description | Default | | ------ | --------------------------------------- | -------------------------------------- | ------- | | use | boolean | Use this middleware for every request. | false | | config | CSRFConfig | koa-csrf configuration. | - |

CSRFConfig

| Name | Type | Description | | ------------------------------ | ----------------- | ----------- | | invalidSessionSecretMessage | string | | | invalidSessionSecretStatusCode | number | | | invalidTokenMessage | string | | | invalidTokenStatusCode | number | | | excludedMethods | string[] | | | disableQuery | boolean | |

BodyparserOptions

| Name | Type | Description | Default | | ------ | --------------------------------------------------- | -------------------------------------- | ------- | | use | boolean | Use this middleware for every request. | false | | config | BodyparserConfig | koa-bodyparser configuration. | - |

import('koa').Context koa.Context

BodyparserConfig

| Name | Type | Description | Default | | ----------- | ----------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------ | ------------------ | | enableTypes | string[] | Parser will only parse when request type hits enableTypes. | ['json', 'form'] | | encode | string | Requested encoding. | utf-8 | | formLimit | string | Limit of the urlencoded body. If the body ends up being larger than this limit a 413 error code is returned. | 56kb | | jsonLimit | string | Limit of the json body. | 1mb | | strict | boolean | When set to true, JSON parser will only accept arrays and objects. | true | | detectJSON | (ctx: Context) => boolean | Custom json request detect function. | null | | extendTypes | { json: string[], form: string[], text: string[] } | Support extend types. | - | | onerror | (err: Error, ctx: Context) => void | Support custom error handle. | - |

CheckauthOptions

| Name | Type | Description | Default | | ---- | ---------------- | -------------------------------------- | ------- | | use | boolean | Use this middleware for every request. | false |

LoggerOptions

| Name | Type | Description | Default | | ------ | ------------------------------------------- | -------------------------------------- | ------- | | use | boolean | Use this middleware for every request. | false | | config | LoggerConfig | koa-logger configuration. | - |

LoggerConfig

| Name | Type | Description | | ----------- | ---------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | transporter | (str: string, args: [string, string, string, string, string, string, string]) => void | Param str is output string with ANSI Color, and you can get pure text with other modules like strip-ansi. Param args is a array by [format, method, url, status, time, length]. |

CompressOptions

| Name | Type | Description | Default | | ------ | ----------------------------------------------- | -------------------------------------- | ------- | | use | boolean | Use this middleware for every request. | false | | config | CompressConfig | koa-compress configuration. | - |

CompressConfig

| Name | Type | Description | Default | | ----------- | ------------------------------------------ | ----------------------------------------------------------------------------------------------------------------------------- | ------- | | filter | (content_type: string) => boolean | An optional function that checks the response content type to decide whether to compress. By default, it uses compressible. | - | | threshold | number | Minimum response size in bytes to compress. | 1024 | | flush | number | Default: zlib.constants.Z_NO_FLUSH. | - | | finishFlush | number | Default: zlib.constants.Z_FINISH. | - | | chunkSize | number | Default: 16*1024. | - | | windowBits | number | Support extend types. | - | | level | number | Compression only. | - | | memLevel | number | Compression only. | - | | strategy | number | Compression only. | - | | dictionary | * | Deflate/inflate only, empty dictionary by default. | - |

StaticOptions

| Name | Type | Description | Default | | --------- | ------------------------------------------- | ------------------------------------------------- | ------- | | root* | (string | string[]) | Root or multiple roots from which to serve files. | - | | use | boolean | Use this middleware for every request. | false | | mount | string | Path from which to serve files. | / | | maxage | number | How long to cache file for. | 0 | | config | StaticConfig | koa-static configuration. | - |

import('http').ServerResponse http.ServerResponse

(res: ServerResponse, path: string, stats: Stats) => any SetHeaders

StaticConfig

| Name | Type | Description | Default | | ---------- | --------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------ | | maxage | number | Browser cache max-age in milliseconds. | 0 | | hidden | boolean | Allow transfer of hidden files. | false | | index | string | Default file name. | index.html | | defer | boolean | If true, serves after return next(), allowing any downstream middleware to respond first. | false | | gzip | boolean | Try to serve the gzipped version of a file automatically when gzip is supported by a client and if the requested file with .gz extension exists. | true | | br | boolean | Try to serve the brotli version of a file automatically when brotli is supported by a client and if the requested file with .br extension exists (note, that brotli is only accepted over https). | true | | setHeaders | SetHeaders | Function to set custom headers on response. | - | | extensions | boolean | Try to match extensions from passed array to search for file when no extension is sufficed in URL. First found is served. | false |

For example, the below configuration will serve files from both the static directory of the project, and the React.js dependency. When NODE_ENV environment variable is set to production, files will be cached for 10 days.

import { join, dirname } from 'path'
import idioCore from '@idio/core'

const STATIC = join(__dirname, 'static')
const REACT = join(dirname(require.resolve('react')), 'umd')

const DAY = 1000 * 60 * 60 * 24

const Static = async () => {
  const { url } = await idioCore({
    static: {
      use: true,
      root: [STATIC, REACT],
      mount: '/scripts',
      maxage: process.env.NODE_ENV == 'production' ? 10 * DAY : 0,
    },
  }, { port: 5004 })
  return url
}

Static server started on http://localhost:5004

import('koa').Context koa.Context

CorsOptions

| Name | Type | Description | Default | | ------ | -------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | ------- | | origin | string|Array|((ctx: Context) => string) | The origin or an array of origins to accept as valid. In case of an array, the origin from the request headers will be searched in the array, and if found, it will be returned (since browsers only support a single Access-Control-Allow-Origin header). If a function is passed, it should return the string with the origin to set. If not passed, the request origin is returned, allowing any origin to access the resource. | - | | use | boolean | Use this middleware for every request. | false | | config | CorsConfig | @koa/cors configuration. | - |

CorsConfig

| Name | Type | Description | Default | | ------------------ | ---------------------------------------- | ------------------------------------------------------ | -------------------------------- | | origin | string | Access-Control-Allow-Origin header value. | request Origin header | | allowMethods | (string | Array<string>) | Access-Control-Allow-Methods header value. | GET,HEAD,PUT,POST,DELETE,PATCH | | exposeHeaders | (string | Array<string>) | Access-Control-Expose-Headers header value. | - | | allowHeaders | (string | Array<string>) | Access-Control-Allow-Headers header value. | - | | maxAge | (string | number) | Access-Control-Max-Age header value in seconds. | - | | credentials | boolean | Access-Control-Allow-Credentials header value. | false | | keepHeadersOnError | boolean | Add set headers to err.header if an error is thrown. | false |

FrontendOptions: Allows to serve front-end JS files and CSS as modules, including from node_modules folder.

| Name | Type | Description | Default | | --------- | ----------------------------------------------- | ------------------------------------------------------- | ---------- | | directory | (string | Array<string>) | The directory or directories from which to serve files. | frontend | | config | FrontendConfig | @idio/frontend configuration. | - |

FrontendConfig

| Name | Type | Description | Default | | ------ | --------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ---------------------------- | | pragma | string | The pragma function to import. This enables to skip writing h at the beginning of each file. JSX will be transpiled to have h pragma, therefore to use React it's possible to do import { createElement: h } from 'react'. | import { h } from 'preact' |

Custom Middleware

When required to add any other middleware in the application not included in the @idio/core bundle, it can be done in several ways.

1. Passing the middleware function as part of the MiddlewareConfig. It will be automatically installed to be used by the Application. All middleware will be installed in order it is found in the MiddlewareConfig.

import idioCore from '@idio/core'

/** @typedef {import('koa').Middleware} Middleware */

const APIServer = async (port) => {
  const { url } = await idioCore({
    // 1. Add logging middleware.
    /** @type {Middleware} */
    async log(ctx, next) {
      await next()
      console.log(' --> API: %s %s %s', ctx.method, ctx.url, ctx.status)
    },
    // 2. Add always used error middleware.
    /** @type {Middleware} */
    async error(ctx, next) {
      try {
        await next()
      } catch (err) {
        ctx.status = 403
        ctx.body = err.message
      }
    },
    // 3. Add validation middleware.
    /** @type {Middleware} */
    async validateKey(ctx, next) {
      if (ctx.query.key !== 'app-secret')
        throw new Error('Wrong API key.')
      ctx.body = 'ok'
      await next()
    },
  }, { port })
  return url
}

export default APIServer

Started API server at: http://localhost:5005
 --> API: GET / 403
 --> API: GET /?key=app-secret 200

2. Passing a configuration object as part of the MiddlewareConfig that includes the middlewareConstructor property which will receive the reference to the app. Other properties such as conf and use will be used in the same way as when setting up bundled middleware: setting use to true will result in the middleware being used for every request, and the config will be passed to the constructor.

import rqt from 'rqt'
import idioCore from '@idio/core'
import APIServer from './api-server'

const ProxyServer = async (port) => {
  // 1. Start the API server.
  const API = await APIServer(5001)
  console.log('API server started at %s', API)

  // 2. Start a proxy server to the API.
  const { url } = await idioCore({
    /** @type {import('koa').Middleware} */
    async log(ctx, next) {
      await next()
      console.log(' --> Proxy: %s %s %s', ctx.method, ctx.url, ctx.status)
    },
    api: {
      use: true,
      async middlewareConstructor(app, config) {
        // e.g., read from a virtual network
        app.context.SECRET = await Promise.resolve('app-secret')

        /** @type {import('koa').Middleware} */
        const fn = async(ctx, next) => {
          const { path } = ctx
          const res = await rqt(`${config.API}${path}?key=${ctx.SECRET}`)
          ctx.body = res
          await next()
        }
        return fn
      },
      config: {
        API,
      },
    },
  }, { port })
  return url
}

API server started at http://localhost:5001
Proxy started at http://localhost:5002
 --> API: GET /?key=app-secret 200
 --> Proxy: GET / 200

Router Set-up

After the Application and Router instances are obtained after starting the server as the app and router properties of the returned object, the router can be configured to respond to custom paths. This can be done by assigning configured middleware from the map and standalone middleware, and calling the use method on the Application instance.

import idioCore from '@idio/core'

async function pre(ctx, next) {
  console.log('  <-- %s %s',
    ctx.request.method,
    ctx.request.path,
  )
  await next()
}

async function post(ctx, next) {
  console.log('  --> %s %s %s',
    ctx.request.method,
    ctx.request.path,
    ctx.response.status,
  )
  await next()
}

const Server = async () => {
  const path = '/test'
  const {
    url, router, app, middleware: { bodyparser },
  } = await idioCore({
    // 1. Configure the bodyparser without using it for each request.
    bodyparser: {
      config: {
        enableTypes: ['json'],
      },
    },
  }, { port: 5003 })

  // 2. Setup router with the bodyparser and path-specific middleware.
  router.post(path,
    pre,
    bodyparser,
    async (ctx, next) => {
      ctx.body = {
        ok: true,
        request: ctx.request.body,
      }
      await next()
    },
    post,
  )
  app.use(router.routes())
  return `${url}${path}`
}

Page available at: http://localhost:5003/test
  <-- POST /test
  --> POST /test 200

Copyright

Middleware icons and logo from Deco Dingbats NF font.

Middleware types descriptions by their respective authors.