Offers getProxyForUrl to get the proxy URL for a URL, respecting the *_PROXY (e.g. HTTP_PROXY) and NO_PROXY environment variables.
npm install proxy-from-env

proxy-from-env is a Node.js package that exports a function (getProxyForUrl)
that takes an input URL (a string orurl.parse's
return value) and returns the desired proxy URL (also a string) based on
standard proxy environment variables. If no proxy is set, an empty string is
returned.
It is your responsibility to actually proxy the request using the given URL.
Installation:
``sh`
npm install proxy-from-env
module, in a proxy-aware way.`javascript
var http = require('http');
var parseUrl = require('url').parse;
var getProxyForUrl = require('proxy-from-env').getProxyForUrl;
var some_url = 'http://example.com/something';
// // Example, if there is a proxy server at 10.0.0.1:1234, then setting the
// // http_proxy environment variable causes the request to go through a proxy.
// process.env.http_proxy = 'http://10.0.0.1:1234';
//
// // But if the host to be proxied is listed in NO_PROXY, then the request is
// // not proxied (but a direct request is made).
// process.env.no_proxy = 'example.com';
var proxy_url = getProxyForUrl(some_url); // <-- Our magic.
if (proxy_url) {
// Should be proxied through proxy_url.
var parsed_some_url = parseUrl(some_url);
var parsed_proxy_url = parseUrl(proxy_url);
// A HTTP proxy is quite simple. It is similar to a normal request, except the
// path is an absolute URL, and the proxied URL's host is put in the header
// instead of the server's actual host.
httpOptions = {
protocol: parsed_proxy_url.protocol,
hostname: parsed_proxy_url.hostname,
port: parsed_proxy_url.port,
path: parsed_some_url.href,
headers: {
Host: parsed_some_url.host, // = host name + optional port.
},
};
} else {
// Direct request.
httpOptions = some_url;
}
http.get(httpOptions, function(res) {
var responses = [];
res.on('data', function(chunk) { responses.push(chunk); });
res.on('end', function() { console.log(responses.join('')); });
});
`
NO_PROXY is a list of host names (optionally with a port). If the input URLNO_PROXY
matches any of the entries in , then the input URL should be fetched
by a direct request (i.e. without a proxy).
Matching follows the following rules:
- NO_PROXY=* disables all proxies.NO_PROXY
- Space and commas may be used to separate the entries in the list.NO_PROXY
- If does not contain any entries, then proxies are never disabled.NO_PROXY
- If a port is added after the host name, then the ports must match. If the URL
does not have an explicit port name, the protocol's default port is used.
- Generally, the proxy is only disabled if the host name is an exact match for
an entry in the list. The only exceptions are entries that start
with a dot or with a wildcard; then the proxy is disabled if the host name
ends with the entry.
See test.js for examples of what should match and what does not.
The environment variable used for the proxy depends on the protocol of the URL.
For example, https://example.com uses the "https" protocol, and therefore theHTTPS_PROXY
proxy to be used is (_NOT_ HTTP_PROXY, which is _only_ used for
http:-URLs).
The library is not limited to http(s), other schemes such as
FTP_PROXY (ftp:),WSS_PROXY (wss:),WS_PROXY (ws:)
are also supported.
If present, ALL_PROXY` is used as fallback if there is no other match.
- cURL:
https://curl.haxx.se/docs/manpage.html#ENVIRONMENT
https://github.com/curl/curl/blob/4af40b3646d3b09f68e419f7ca866ff395d1f897/lib/url.c#L4446-L4514
https://github.com/curl/curl/blob/4af40b3646d3b09f68e419f7ca866ff395d1f897/lib/url.c#L4608-L4638
- wget:
https://www.gnu.org/software/wget/manual/wget.html#Proxies
http://git.savannah.gnu.org/cgit/wget.git/tree/src/init.c?id=636a5f9a1c508aa39e35a3a8e9e54520a284d93d#n383
http://git.savannah.gnu.org/cgit/wget.git/tree/src/retr.c?id=93c1517c4071c4288ba5a4b038e7634e4c6b5482#n1278
- W3:
https://www.w3.org/Daemon/User/Proxies/ProxyClients.html
- Python's urllib:
https://github.com/python/cpython/blob/936135bb97fe04223aa30ca6e98eac8f3ed6b349/Lib/urllib/request.py#L755-L782
https://github.com/python/cpython/blob/936135bb97fe04223aa30ca6e98eac8f3ed6b349/Lib/urllib/request.py#L2444-L2479