h20-2

h2o2

Proxy handler plugin for hapi.js.

Lead Maintainer - Sanjay Pandit

Introduction

h2o2 is a hapi plugin that adds proxying functionality.

Manual loading

H2o2 version 7 requires Hapi 17. For use with Hapi v16.x.x, please use H2o2 @v6.x.x

Starting on version 9, hapi does not load the h2o2 automatically. To add h2o2 to your server, you should register it normally.

const Hapi = require('hapi');
const server = Hapi.server();

const startServer = async function() {
  try {
    await server.register({ plugin: require('h2o2') });
    await server.start();

    console.log(`Server started at:  ${server.info.uri}`);
  }
  catch(e) {
    console.log('Failed to load h2o2');
  }
}

startServer();

NOTE: h2o2 is included with and loaded by default in Hapi < 9.0.

Options

The plugin can be registered with an optional object specifying defaults to be applied to the proxy handler object.

The proxy handler object has the following properties:

• host - upstream service host to proxy requests to. It will have the same path as the client request.
• port - upstream service port.
• protocol - protocol to use when making the request to the proxied host:
  • 'http'
  • 'https'
• uri - absolute URI used instead of host, port, protocol, path, and query. Cannot be used with host, port, protocol, or mapUri.
• httpClient - an http client that abides by the Wreck interface. Defaults to wreck.
• passThrough - if set to true, it forwards the headers from the client to the upstream service, headers sent from the upstream service will also be forwarded to the client. Defaults to false.
• localStatePassThrough - if set tofalse, any locally defined state is removed from incoming requests before being sent to the upstream service. This value can be overridden on a per state basis via the server.state() passThrough option. Defaults to false
• acceptEncoding - if set to false, does not pass-through the 'Accept-Encoding' HTTP header which is useful for the onResponse post-processing to avoid receiving an encoded response. Can only be used together with passThrough. Defaults to true (passing header).
• rejectUnauthorized - sets the rejectUnauthorized property on the https agent making the request. This value is only used when the proxied server uses TLS/SSL. If set it will override the node.js rejectUnauthorized property. If false then ssl errors will be ignored. When true the server certificate is verified and an 500 response will be sent when verification fails. This shouldn't be used alongside the agent setting as the agent will be used instead. Defaults to the https agent default value of true.
• xforward - if set to true, sets the 'X-Forwarded-For', 'X-Forwarded-Port', 'X-Forwarded-Proto', 'X-Forwarded-Host' headers when making a request to the proxied upstream endpoint. Defaults to false.
• redirects - the maximum number of HTTP redirections allowed to be followed automatically by the handler. Set to false or 0 to disable all redirections (the response will contain the redirection received from the upstream service). If redirections are enabled, no redirections (301, 302, 307, 308) will be passed along to the client, and reaching the maximum allowed redirections will return an error response. Defaults to false.
• timeout - number of milliseconds before aborting the upstream request. Defaults to 180000 (3 minutes).
• mapUri - a function used to map the request URI to the proxied URI. Cannot be used together with host, port, protocol, or uri. The function signature is function (request) where:
  • request - is the incoming request object. The response from this function should be an object with the following properties:
    • uri - the absolute proxy URI.
    • headers - optional object where each key is an HTTP request header and the value is the header content.
• onRequest - a custom function which is passed the upstream request. Function signature is function (req) where:
  • req - the [wreck] (https://github.com/hapijs/wreck) request to the upstream server.
• onResponse - a custom function for processing the response from the upstream service before sending to the client. Useful for custom error handling of responses from the proxied endpoint or other payload manipulation. Function signature is function (err, res, request, h, settings, ttl) where:
  • err - internal or upstream error returned from attempting to contact the upstream proxy.
  • res - the node response object received from the upstream service. res is a readable stream (use the wreck module read method to easily convert it to a Buffer or string).
  • request - is the incoming request object.
  • h - the response toolkit.
  • settings - the proxy handler configuration.
  • ttl - the upstream TTL in milliseconds if proxy.ttl it set to 'upstream' and the upstream response included a valid 'Cache-Control' header with 'max-age'.
• ttl - if set to 'upstream', applies the upstream response caching policy to the response using the response.ttl() method (or passed as an argument to the onResponse method if provided).
• agent - a node http(s) agent to be used for connections to upstream server.
• maxSockets - sets the maximum number of sockets available per outgoing proxy host connection. false means use the wreck module default value (Infinity). Does not affect non-proxy outgoing client connections. Defaults to Infinity.
• secureProtocol - TLS flag indicating the SSL method to use, e.g. SSLv3_method to force SSL version 3. The possible values depend on your installation of OpenSSL. Read the official OpenSSL docs for possible SSL_METHODS.
• ciphers - TLS list of TLS ciphers to override node's default. The possible values depend on your installation of OpenSSL. Read the official OpenSSL docs for possible TLS_CIPHERS.
• downstreamResponseTime - logs the time spent processing the downstream request using process.hrtime. Defaults to false.

Usage

As one of the handlers for hapi, it is used through the route configuration object.

h.proxy(options)

Proxies the request to an upstream endpoint where:

• options - an object including the same keys and restrictions defined by the route proxy handler options.

No return value.

The response flow control rules do not apply.

const handler = function (request, h) {

    return h.proxy({ host: 'example.com', port: 80, protocol: 'http' });
};

Using the host, port, protocol options

Setting these options will send the request to certain route to a specific upstream service with the same path as the original request. Cannot be used with uri, mapUri.

server.route({
    method: 'GET',
    path: '/',
    handler: {
        proxy: {
            host: '10.33.33.1',
            port: '443',
            protocol: 'https'
        }
    }
});

Using the uri option

Setting this option will send the request to an absolute URI instead of the incoming host, port, protocol, path and query. Cannot be used with host, port, protocol, mapUri.

server.route({
    method: 'GET',
    path: '/',
    handler: {
        proxy: {
            uri: 'https://some.upstream.service.com/that/has?what=you&want=todo'
        }
    }
});

Custom uri template values

When using the uri option, there are optional default template values that can be injected from the incoming request:

• {protocol}
• {host}
• {port}
• {path}

server.route({
    method: 'GET',
    path: '/foo',
    handler: {
        proxy: {
            uri: '{protocol}://{host}:{port}/go/to/{path}'
        }
    }
});

Requests to http://127.0.0.1:8080/foo/ would be proxied to an upstream destination of http://127.0.0.1:8080/go/to/foo

Additionally, you can capture request.params values and inject them into the upstream uri value using a similar replacment strategy:

server.route({
    method: 'GET',
    path: '/foo/{bar}',
    handler: {
        proxy: {
            uri: 'https://some.upstream.service.com/some/path/to/{bar}'
        }
    }
});

Note The default variables of {protocol}, {host}, {port}, {path} take precedence - it's best to treat those as reserved when naming your own request.params.

Using the mapUri and onResponse options

Setting both options with custom functions will allow you to map the original request to an upstream service and to processing the response from the upstream service, before sending it to the client. Cannot be used together with host, port, protocol, or uri.

server.route({
    method: 'GET',
    path: '/',
    handler: {
        proxy: {
            mapUri: function (request) {

                console.log('doing some additional stuff before redirecting');
                return {
                    uri: 'https://some.upstream.service.com/'
                };
            },
            onResponse: function (err, res, request, h, settings, ttl) {

                console.log('receiving the response from the upstream.');
                Wreck.read(res, { json: true }, function (err, payload) {

                    console.log('some payload manipulation if you want to.')
                    const response = h.response(payload);
                    response.headers = res.headers;
                    return response;
                });
            }
        }
    }
});

Using a custom http client

By default, h2o2 uses Wreck to perform requests. A custom http client can be provided by passing a client to httpClient, as long as it abides by the wreck interface. The two functions that h2o2 utilizes are request() and parseCacheControl().

server.route({
    method: 'GET',
    path: '/',
    handler: {
        proxy: {
            httpClient: {
                request(method, uri, options) {
                    return axios({
                        method,
                        url: 'https://some.upstream.service.com/'
                    })
                }
            }
        }
    }
});