fastify-reply-from

fastify-reply-from

fastify plugin to forward the current http request to another server. HTTP2 to HTTP is supported too.

Install

npm i fastify-reply-from

Compatibility with fastify-multipart

fastify-reply-from and fastify-multipart should not be registered as sibling plugins nor should they be registered in plugins which have a parent-child relationship.
The two plugins are incompatible, in the sense that the behavior of fastify-reply-from might not be the expected one when the above-mentioned conditions are not respected.
This is due to the fact that fastify-multipart consumes the multipart content by parsing it, hence this content is not forwarded to the target service by fastify-reply-from.
However, the two plugins may be used within the same fastify instance, at the condition that they belong to disjoint branches of the fastify plugins hierarchy tree.

Usage

The following example set up two fastify servers and forward the request from one to the other.

'use strict'

const Fastify = require('fastify')

const target = Fastify({
  logger: true
})

target.get('/', (request, reply) => {
  reply.send('hello world')
})

const proxy = Fastify({
  logger: true
})

proxy.register(require('fastify-reply-from'), {
  base: 'http://localhost:3001/'
})

proxy.get('/', (request, reply) => {
  reply.from('/')
})

target.listen(3001, (err) => {
  if (err) {
    throw err
  }

  proxy.listen(3000, (err) => {
    if (err) {
      throw err
    }
  })
})

API

Plugin options

base

Set the base URL for all the forwarded requests. Will be required if http2 is set to true Note that every path will be discarded.

Custom URL protocols unix+http: and unix+https: can be used to forward requests to a unix socket server by using querystring.escape(socketPath) as the hostname. This is not supported for http2 nor undici. To illustrate:

const socketPath = require('querystring').escape('/run/http-daemon.socket')
proxy.register(require('fastify-reply-from'), {
  base: 'unix+http://${socketPath}/'
});

http

By default, Node's http.request will be used if you do not enable http2 or undici. To customize the request, you can pass in agentOptions and requestOptions. To illustrate:

proxy.register(require('fastify-reply-from'), {
  base: 'http://localhost:3001/',
  http: {
    agentOptions: { // pass in any options from https://nodejs.org/api/http.html#http_new_agent_options
      keepAliveMsecs: 10 * 60 * 1000
    },
    requestOptions: { // pass in any options from https://nodejs.org/api/http.html#http_http_request_options_callback
      timeout: 5000 // timeout in msecs, defaults to 10000 (10 seconds)
    }
  }
})

You can also pass custom http agents. If you pass the agents, then the http.agentOptions will be ignored. To illustrate:

proxy.register(require('fastify-reply-from'), {
  base: 'http://localhost:3001/',
  http: {
    agents: {
      'http:': new http.Agent({ keepAliveMsecs: 10 * 60 * 1000 }), // pass in any options from https://nodejs.org/api/http.html#http_new_agent_options
      'https:': new https.Agent({ keepAliveMsecs: 10 * 60 * 1000 })

    },
    requestOptions: { // pass in any options from https://nodejs.org/api/http.html#http_http_request_options_callback
      timeout: 5000 // timeout in msecs, defaults to 10000 (10 seconds)
    }
  }
})

http2

You can either set http2 to true or set the settings object to connect to a HTTP/2 server. The http2 settings object has the shape of:

proxy.register(require('fastify-reply-from'), {
  base: 'http://localhost:3001/',
  http2: {
    sessionTimeout: 10000, // HTTP/2 session timeout in msecs, defaults to 60000 (1 minute)
    requestTimeout: 5000, // HTTP/2 request timeout in msecs, defaults to 10000 (10 seconds)
    sessionOptions: { // HTTP/2 session connect options, pass in any options from https://nodejs.org/api/http2.html#http2_http2_connect_authority_options_listener
      rejectUnauthorized: true
    },
    requestTimeout: { // HTTP/2 request options, pass in any options from https://nodejs.org/api/http2.html#http2_clienthttp2session_request_headers_options
      endStream: true
    }
  }
})

undici

Set to true to use undici instead of require('http'). Enabling this flag should guarantee 20-50% more throughput.

This flag could controls the settings of the undici client, like so:

proxy.register(require('fastify-reply-from'), {
  base: 'http://localhost:3001/',
  undici: {
    connections: 100,
    pipelining: 10
  }
})

cacheURLs

The number of parsed URLs that will be cached. Default: 100.

keepAliveMsecs

(Deprecated) Defaults to 1 minute (60000), passed down to http.Agent and https.Agent instances. Prefer to use http.agentOptions instead.

maxSockets

(Deprecated) Defaults to 2048 sockets, passed down to http.Agent and https.Agent instances. Prefer to use http.agentOptions instead.

maxFreeSockets

(Deprecated) Defaults to 2048 free sockets, passed down to http.Agent and https.Agent instances. Prefer to use http.agentOptions instead.

rejectUnauthorized

(Deprecated) Defaults to false, passed down to https.Agent instances. This needs to be set to false to reply from https servers with self-signed certificates. Prefer to use http.requestOptions or http2.sessionOptions instead.

sessionTimeout

(Deprecated) The timeout value after which the HTTP2 client session is destroyed if there is no activity. Defaults to 1 minute (60000). Prefer to use http2.sessionTimeout instead.

---

reply.from(source, [opts])

The plugin decorates the Reply instance with a from method, which will reply to the original request from the desired source. The options allows to override any part of the request or response being sent or received to/from the source.

Note: If base is specified in plugin options, the source here should not override the host/origin.

onResponse(request, reply, res)

Called when an http response is received from the source. The default behavior is reply.send(res), which will be disabled if the option is specified.

When replying with a body of a different length it is necessary to remove the content-length header.

{
  onResponse: (request, reply, res) => {
    reply.removeHeader('content-length');
    reply.send('New body of different length');
  }
}

onError(reply, error)

Called when an http response is received with error from the source. The default behavior is reply.send(error), which will be disabled if the option is specified. It must reply the error.

rewriteHeaders(headers)

Called to rewrite the headers of the response, before them being copied over to the outer response. It must return the new headers object.

rewriteRequestHeaders(originalReq, headers)

Called to rewrite the headers of the request, before them being sent to the other server. It must return the new headers object.

queryString

Replaces the original querystring of the request with what is specified. This will be passed to querystring.stringify.

body

Replaces the original request body with what is specified. Unless [contentType][contentType] is specified, the content will be passed through JSON.stringify(). Setting this option will not verify if the http method allows for a body.

contentType

Override the 'Content-Type' header of the forwarded request, if we are already overriding the [body][body].

HTTP & HTTP2 timeouts

This library has:

• timeout for http set by default. The default value is 10 seconds (10000).
• requestTimeout & sessionTimeout for http2 set by default.
  • The default value for requestTimeout is 10 seconds (10000).
  • The default value for sessionTimeout is 60 seconds (60000).

When a timeout happens, 504 Gateway Timeout will be returned to the client.

TODO

• support overriding the body with a stream
• forward the request id to the other peer might require some refactoring because we have to make the req.id unique (see hyperid).
• Support origin HTTP2 push
• benchmarks

License

MIT