Is there a way to enable keep-alive?

[voronianski]

I'm running several express apps via this proxy. But http://www.webpagetest.org/ test complains about Keep-Alive not Enabled. I assume that it's an issue with proxy, is there a way to enable keep-alive?

[jcrugzz]

@voronianski use something like keep-alive-agent or agentkeepalive or even the standard http.Agent. Just make sure you pass in maxSockets: 100(+)

For a why explanation...

We default to connection: close when there is no agent passed in to work around a bug in node core when we set agent: false. We default to setting agent: false to begin with as it enables the operating system itself to handle the number of sockets that get opened.

[jcrugzz]

Marked as FAQ and closing. Let me know if there are any more questions on this.

[voronianski]

@jcrugzz could you help with the right place to add the agent?

From the docs I see that it's used in http.request options, but how it could be passed on http create server?

var http = require('http');
var proxy = require('http-proxy').createProxy();
var address = require('network-address');
var config = require('../config');

http.createServer(function (req, res) {
    proxy.web(req, res, {
        target: config.router[req.headers.host]
    }, function (e) {
        console.error(e);
        res.writeHead(500, {'Content-Type': 'text/plain'});
        res.end('Something went wrong. Please try again.');
    });
}).listen(80);
console.log('Proxy server started at ' + address());

[jcrugzz]

@voronianski its one of the options you pass into the http-proxy constructor. So you would change the above to...

var http = require('http');
var agent = new http.Agent({ maxSockets: Number.MAX_VALUE });
var proxy = require('http-proxy').createProxy({ agent: agent });
var address = require('network-address');
var config = require('../config');

http.createServer(function (req, res) {
    proxy.web(req, res, {
        target: config.router[req.headers.host]
    }, function (e) {
        console.error(e);
        res.writeHead(500, {'Content-Type': 'text/plain'});
        res.end('Something went wrong. Please try again.');
    });
}).listen(80);
console.log('Proxy server started at ' + address());

[voronianski]

@jcrugzz thanks!

[webuniverseio]

@jcrugzz, I'm trying to wrap my head around why one would want to specify maxSockets? It seems that it is not a maxSockets value which is making connection to change to 'keep-alive'. It is enough to just have http.Agent instance. I tried to debug core http module, but stuck on what exactly is causing it to pick keepAlive setting even when it is not set to true on the agent instance. Can you please give me a hint? Thanks.

[jcrugzz]

@szarouski this is because the default maxSockets value is 5 which is insanely low and not recommended for production use at all. The agent itself is in charge of handling keep-alive

[webuniverseio]

Oh I see. It changed at v0.11.6 to Infinity. It is a bit confusing that agent will maintain keep-alive even if keepAlive property was never set and therefor is set by default to false.