Enterprise Rails

Growing Slowly

Every website begins its life with a single developer and a single line of code. Figure 1-1 shows a simple configuration of a Rails application connected to a database. You will likely spend quite a bit of time developing your application on this setup before it’s ready for its first user.

Figure 1-1. A basic website configuration

When it’s time to launch, there some issues that ought to be considered. Figure 1-2 shows the same configuration, but with redundancy at the application level, and failover at the database level.

There are two copies of the application so that in the event one machine fails, there is still another that can handle incoming traffic. Similarly, in the event of a hardware failure on the database machine, a copy that is a transaction or two behind can be brought online quickly.

Figure 1-2. A basic website configuration with failover and redundancy

Even if you are barely using any of the resources on either the application or database machine, redundancy and failover are a very good idea. At this point, neither of these considerations is aimed at managing load—that comes later. Rather, both are intended to ensure the availability of your web application. Reprovisioning a machine, configuring it, and loading all your software and data from backups can cause ...