This solves two gotchas I came across when deploying a node site running express through systemd: 1) Remove the callback in `listen` or the requests will hang, and 2) tell systemd what the working directory for your app is.

app.js

var express = require('express')
  , http = require('http')
  , path = require('path');

require('systemd');

var app = express();

// configuration and routes go here...

http.createServer(app).listen(app.get('port'));

mysite.service

[Service]
ExecStart=/usr/bin/node /srv/http/mysite/app.js
StandardOutput=journal+console
StandardError=journal+console
SyslogIdentifier=mysite
User=http
Group=http
WorkingDirectory=/srv/http/mysite/
Environment=PATH=/usr/bin:/usr/lib/
Environment=NODE_ENV=production

mysite.socket

[Socket]
ListenStream=/run/systemd/system/node-mysite.sock

[Install]
WantedBy=sockets.target