nginx

Installation

Years ago, if you wanted to install nearly any open-source software, you needed to download a .tar.gz file, open it, modify the configuration, compile it and install it. Today, of course, you can install things on a Linux box running Debian or Ubuntu with a simple apt-get command. For example, I can install nginx as follows:


apt-get install nginx

But, wait a second. If nginx cannot be modified after I compile it, perhaps I should check to see how I can modify the configuration I'll get from the default installation. And of course, while you can change the server configuration, you cannot change the modules that are compiled into the server. So making sure that the right modules are compiled into nginx is pretty important before installing it.

On the Ubuntu 14.04 server I used for testing, running apt-cache search nginx revealed the following options:

  • nginx-extras

  • nginx-full

  • nginx-light

Which one is appropriate for you, or should you try something else? The answer, of course, depends on what you want to do.

If you want to serve static files, any of these will do just fine. Even nginx-light, the smallest of the bunch, has features like SSL, gzip and rewriting built in to it. Indeed, nginx-light even includes fastcgi, the module you'll need if you want to run a program like WordPress.

But, let's say you want to deploy Ruby on Rails applications, using the Phusion Passenger add-on. Which version of nginx should you install to run that? The answer, quite simply, is "none of them". nginx will need to be recompiled in order to install Passenger. This is, oddly enough, not as painful as you might expect. However, it does mean that before you even can decide how to install nginx, you need to consider what you want to do with it.

Static Pages

Let's start exploring nginx by installing the nginx-lite package under Ubuntu, then looking at the configuration and how you can get a basic static site running.

First, I'm going to install the nginx-core package:


$ sudo apt-get install nginx-core

I then can start the server with the fairly standard shell command:


$ sudo service nginx start

After a few moments, nginx will have started, as I can tell either by typing this:


$ sudo serviced nginx status

to which I get the response:


nginx is running

And if I go to the home page on my current server, I'm greeted by, "Welcome to nginx!"

But of course, I'd really like to have my own content there. Let's take a look at the configuration file, which is in /etc/nginx/nginx.conf on my system, and see how it's formatted and how to change it to make some custom static content.

Now, if you're used to Apache configuration files, the style of nginx's file is going to take some getting used to. Like Apache, each line contains a configuration setting in a name-value style. Unlike Apache, the sections are delimited using curly braces ({ }), and each line must end with a semicolon (;). For example, the first line in my installed, default nginx configuration file is:


user www-data;

This means nginx will run as the www-data user, which is pretty standard in the world of Ubuntu (and Debian). Next comes the configuration parameter:


worker_processes 4;

This describes how many processes nginx should launch when running. But, it would seem to contradict what I wrote above, namely that nginx uses only a single process (and no threads within that process) for extra speed, no? Well, yes and no—the idea is that you'll probably want to have one nginx worker process per CPU core on your server. On this server, I have four cores, each of which can (and should) have an nginx worker process. You can think of this as a one-computer version of a load balancer, distributing the load across the available CPUs. Each worker process can and will handle a large number of network connections.

If your server will be running more than just nginx—for example, if you are running a database server on the same machine—you likely will want to reduce this number, so that at least one core is always available for those other processes.

The default configuration file then contains an "events" section:


events {
        worker_connections 768;
        # multi_accept on;
}

In this, I set worker_connections—meaning, how many network connections can each worker process handle simultaneously? In this case, it's set to 768; I'm not sure where this number comes from, but it means that if my site becomes popular, I might find that I run out of network connections. You might well want to raise this number.

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