What is agent-base?
The agent-base package is a module for Node.js that allows you to create custom HTTP/HTTPS Agents. It is used to implement custom proxying behavior, connection pooling, and other HTTP client enhancements. It provides a simple way to extend the core `http.Agent` class to customize the behavior of HTTP requests.
What are agent-base's main functionalities?
Custom HTTP Agent
This feature allows you to create a custom HTTP agent by providing a function that handles HTTP requests. The function can perform custom logic and must return a stream, socket, or an existing agent.
const agent = require('agent-base');
function myAgent(request, options) {
// Custom logic for handling HTTP requests
return new Promise((resolve, reject) => {
// Resolve with a custom stream, socket, or an existing agent
resolve(myCustomStreamOrSocket);
});
}
module.exports = agent(myAgent);
HTTPS Agent with Custom Certificate
This feature demonstrates how to create an HTTPS agent with a custom certificate. The agent is created by extending the `https.Agent` class and adding custom options, such as SSL key and certificate.
const agent = require('agent-base');
const https = require('https');
const fs = require('fs');
const options = {
key: fs.readFileSync('key.pem'),
cert: fs.readFileSync('cert.pem')
};
const httpsAgent = agent((req, opts) => {
return new Promise((resolve, reject) => {
opts = Object.assign({}, opts, options);
resolve(new https.Agent(opts));
});
});
module.exports = httpsAgent;
Other packages similar to agent-base
http-proxy-agent
The http-proxy-agent package provides an HTTP Agent implementation that connects to a specified HTTP proxy server. It is similar to agent-base in that it allows you to customize the behavior of HTTP requests, but it is specifically designed for proxying.
https-proxy-agent
Similar to http-proxy-agent, https-proxy-agent is an HTTPS Agent implementation for proxying HTTPS requests. It provides similar functionality to agent-base but is tailored for HTTPS connections through a proxy server.
socks-proxy-agent
The socks-proxy-agent package is an HTTP Agent that connects to a SOCKS proxy server. It is another example of a package that extends the functionality of the core HTTP Agent, similar to agent-base, but with a focus on SOCKS proxy support.
agent-base
Turn a function into an http.Agent
instance
This module provides an http.Agent
generator. That is, you pass it an async
callback function, and it returns a new http.Agent
instance that will invoke the
given callback function when sending outbound HTTP requests.
Some subclasses:
Here's some more interesting uses of agent-base
.
Send a pull request to list yours!
Installation
Install with npm
:
$ npm install agent-base
Example
Here's a minimal example that creates a new net.Socket
connection to the server
for every HTTP request (i.e. the equivalent of agent: false
option):
var net = require('net');
var tls = require('tls');
var url = require('url');
var http = require('http');
var agent = require('agent-base');
var endpoint = 'http://nodejs.org/api/';
var parsed = url.parse(endpoint);
parsed.agent = agent(function (req, opts) {
var socket;
if (opts.secureEndpoint) {
socket = tls.connect(opts);
} else {
socket = net.connect(opts);
}
return socket;
});
http.get(parsed, function (res) {
console.log('"response" event!', res.headers);
res.pipe(process.stdout);
});
Returning a Promise or using an async
function is also supported:
agent(async function (req, opts) {
await sleep(1000);
});
Return another http.Agent
instance to "pass through" the responsibility
for that HTTP request to that agent:
agent(function (req, opts) {
return opts.secureEndpoint ? https.globalAgent : http.globalAgent;
});
API
Agent(Function callback[, Object options]) → http.Agent
Creates a base http.Agent
that will execute the callback function callback
for every HTTP request that it is used as the agent
for. The callback function
is responsible for creating a stream.Duplex
instance of some kind that will be
used as the underlying socket in the HTTP request.
The options
object accepts the following properties:
timeout
- Number - Timeout for the callback()
function in milliseconds. Defaults to Infinity (optional).
The callback function should have the following signature:
callback(http.ClientRequest req, Object options, Function cb) → undefined
The ClientRequest req
can be accessed to read request headers and
and the path, etc. The options
object contains the options passed
to the http.request()
/https.request()
function call, and is formatted
to be directly passed to net.connect()
/tls.connect()
, or however
else you want a Socket to be created. Pass the created socket to
the callback function cb
once created, and the HTTP request will
continue to proceed.
If the https
module is used to invoke the HTTP request, then the
secureEndpoint
property on options
will be set to true
.
License
(The MIT License)
Copyright (c) 2013 Nathan Rajlich <nathan@tootallnate.net>
Permission is hereby granted, free of charge, to any person obtaining
a copy of this software and associated documentation files (the
'Software'), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject to
the following conditions:
The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.