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Having so many users of the application is a success as well as a challenge for its creators. In the first place, you have to deal with the growing interest in your product or service. On the other hand, lack of appropriate technical preparation can lead to the collapse of the application. Fortunately, there is a solution for this. With our help you will learn how to scale your Ruby on Rails application.

What is the scalability of the framework?

Scaling a framework by definition refers to the application's potential to generate more requests per minute (RPM). The priority is not so much to take care of the framework itself, but the infrastructure of the entire server system. Take a look at how this works in practice.

Imagine a skyscraper with only one elevator that can accommodate a few people. The interest in enjoying the landscape is so high that the elevator gets overcrowded and can't function properly. To prevent this from happening, it is important to ensure that proper infrastructure is in place before the building is completed or to create a solution to transport more people to the top. The described elevator is equivalent to an application that does not have the right scaling. As a result, losses are incurred that can be extremely painful.

how to scale app

What if you don't take care to scale your application?

Failure to scale in response to traffic growth can lead to application slowdowns and even crashes. This is just the beginning of possible troubles. Delaying a solution may cause customers to leave, and their dissatisfaction will translate into online reviews. Instead of downplaying, you should take quick steps to improve scaling.

Which obstacles might you encounter while scaling your application?

It's easy to talk about scaling, but hard to implement in reality. One of the obstacles may be the application architecture. If solutions that find themselves in the reality of high interest have not been implemented, there may be problems with request handling, for example. For RoR applications, the framework recommends clean, modular code. This favors integration with more database management systems. What's more, placing load balancers to process more requests is not a problem either.

Ruby on Rails scalability is also dependent on server bandwidth. An increase in interest from users can put a significant strain on its capacity. Consequently, the application will lose its speed. This is not the only reason that can cause the application to slow down.

Examples of reasons for slow scaling in Ruby:

  • improper database queries
  • no possibility of logging or monitoring
  • errors at the stage of selecting a database engine 
  • low caching speed
  • inefficiency in indexing

Despite the examples above, Ruby on Rails provides developers with many conveniences. It features clean, modular code that enables extended integration with systems responsible for database management. This doesn’t solve all the problems with the application architecture, but it gives additional possibilities.

Vertical scalability with Ruby on Rails

Vertical scaling is considered to be the simplest method to make a server perform better. In practice, this means increasing RAM, and upgrading the server's processor. These types of actions have a common goal - to increase power. But it brings results only in the initial phase. Over time, as traffic increases, you will reach a point where further modifications and improvements are technically impossible.

Horizontal scalability with Ruby on Rails

Horizontal scaling is slightly different. This solution is based on the conversion of a single application server architecture to a three-tier architecture. In this case, the server and load balancer (Nginx), app instances, as well as database instances are located on different servers. Such a split generates equal and lesser machine loads.

scalability with Ruby on Rails


Nginx is a frequently used server software designed for Rails applications. It's placed on a single machine in the role of load balancer and reverse-proxy. All because it doesn't require much computing power to function properly under high loads. The most important role of Nginx is to filter and distribute the load among many servers.

The server configuration is done in such a way that each request is assigned to the appropriate computer. The first request to the first device, the second to the second, the third to the third etc. If there are more requests than resources, then each redundant request is reassigned to the first machine.

App Instances

An important factor occurring in the scaling architecture is the configuration of communication between the various application resources where Rails workloads are placed. The servers of each application are responsible for the proper flow of communication between the web servers. As a result, the amount of queries processed per second increases. Rails allows an application server to manage multiple application resources. However, it is worth remembering that Rack can be used for good communication with the web server. This is an interface that provides equal standards between standalone application servers.

Database scaling

Transporting databases and placing them on a separate server used by app instances is one way to lead to scaling Rails applications. Dealing with databases can significantly reduce the execution time of queries. All because the query in such a situation does not need to go through multiple database instances that hold the data. This allows each query to go directly to a place where everything is organized and ready to be shared.

Additional methods of scaling

Not everyone realizes that scaling is associated with additional expenses. Especially when further development of the project is assumed. There are several solutions that can help reduce costs. One of them is to optimize the code at the stage of application development. Fast application development is not synonymous with properly optimized code. Therefore, it is advisable to use automatic tools to check the code, which will allow developers to adjust it for optimal server usage. 

An alternative to this solution is to develop an application architecture that is service-oriented in order to scale. In such a situation, the part of the application assigned to a specific function can be implemented on the server as a separate application. This will result in less load on the main server. Also, splitting a Ruby on Rails application into parts is simpler and cheaper. Service-Oriented Architecture is one of the most common methods of scaling Rails applications.

scaling rails

Examples of problems with scaling RoR apps

Developing applications based on the RoR framework has its benefits, but it can also cause all sorts of problems. One of the obstacles can be the previously mentioned rapid growth. This is not the only scalability issue that application owners face. Inadequate memory management, database engine with low efficiency, or improper indexing can provide additional responsibilities. Despite the mentioned examples, you should not be discouraged from developing applications in this framework. The Ruby on Rails community is irreplaceable, and their experience and described cases help in crisis situations.


Scaling a Ruby on Rails-based application should depend on the type of project. RoR, like many other technologies, is not the answer to all needs. Therefore, before creating an application, it is worth considering your business profile and comparing it with Rails capabilities. If you need expert RoR support, we recommend working with Railwaymen. We have experienced professionals on our team who will be happy to help you at every stage of application development.