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Building Apps with Scale in Mind: Key Considerations and Strategies

· 7 min read
Jens Langhammer
Jens Langhammer
CTO at Authentik Security Inc

When building apps with scale in mind, the fundamentals involve designing and developing applications in a way that allows them to handle increased user demand, larger data volumes, and growing functionality without compromising performance or stability. Scaling an application effectively requires careful planning, architecture design, and the use of scalable technologies. This blog will explore some key considerations and strategies for building apps for scalability.

The primary considerations when developing a scalable application include:

  • Architecture, both of the application and the system on which it runs
  • System scalability, such as horizontal scaling and containerization
  • Database scaling: a scalable app depends on scalable data access
  • Asynchronous processing, with message queues and background processing
  • Performance optimization, for code and queries
  • Fault tolerance and failover, to keep your application operational

Let’s look more closely at each of these topics, and also discuss the use of Cloud infrastructure, Agile development technologies, as well as testing and monitoring your application.

Modular and Scalable Architecture​

A modular architecture with separate application components, such as the user interface, business logic, and data storage, allows for independent scaling of different modules based on demand. Two popular architectures for applications that need scalability are MVC and microservices.

The Model-View-Controller Pattern​

A classic architecture with a layered approach like the Model-View-Controller (MVC) pattern enables the scaling of individual components without affecting the entire app.The MVC architecture has been around for decades now, but remains popular and effective. Both Laravel and Spring use MVC, and Ruby on Rails, Angular,js, and Django use variations of MVC. For Django, the architecture is referred to as MVT (Model-View-Template), and the data written to the template comes from the model layer, and is “controlled” by the Django framework itself.

Microservices Architecture​

Another option is to adopt a microservices architecture, where each app component runs as a separate service with its own data storage, deployment, and scaling capabilities. This approach can provide greater flexibility and resilience, as individual services can be scaled, updated, or replaced without affecting the entire app. While microservices architecture offers several advantages, it also introduces certain complexities. Managing multiple services can be challenging, as it requires coordination and can result in increased network latency. Ensuring data consistency across different services is another common concern. Here, with authentik, we chose to use a mono-repo approach, but perhaps the most well-known example of successful (and necessary) microservices architecture is OpenStack.

Horizontal Scaling for System Servers​

The architecture of your system also matters. Horizontal scaling means adding more resources, typically of the same type, to the system. Rapid, even automated, horizontal scaling ensures that your app keeps running, no matter the demand. Plan for horizontal scaling. By planning ahead and adding more servers or instances, you can distribute the workload across multiple resources, ensuring your app can easily handle high traffic.

Load Balancing​

To achieve scalability, design your app to support load balancing and implement cutting-edge techniques like clustering or containerization. These strategies will help you respond quickly to sudden surges in demand and keep your app running smoothly. Imagine the benefits for your business when you can seamlessly handle significant increases in user traffic, and then scale back down when the extra resources are no longer needed. Focus on building a scalable app that can effectively handle varying levels of demand and remain prepared for any scenario.

Clustering and Containerization​

Clustering and containerization have revolutionized the way we build and deploy applications. With clustering, you can combine multiple servers or instances to work together seamlessly, providing an unparalleled level of fault tolerance and load distribution. And with containerization, deploying your app across multiple environments has never been easier. Simply package your app and its dependencies into a portable container, and voila - you're ready to scale up and deploy across multiple servers or instances. Both of these technologies are incredibly flexible, making them perfect for any project, big or small.

Database Scalability​

Just as your environment and system needs to be scalable, so does your underlying database. There have been massive technological leaps in database scalability; take advantage of the following practices to ensure rapid and consistent data access for your application.

Distributed Databases and Sharding​

With the vast amount of data and high traffic typical of modern applications, selecting a distributed database that provides replication and sharding, such as PostgreSQL, is crucial. By distributing data across multiple servers, you can handle large volumes of information without any hiccups. Sharding provides yet further data distribution; chunks of data are stored on different database tables, or nodes, and optionally on different machines. Automated sharding means that a single database or server never gets overloaded; the data load is smoothly distributed and performance of the application is not compromised.

Caching Mechanisms​

Caching is an effective way to boost the performance of your website or application. By implementing caching mechanisms such as Redis or Memcached, you can store frequently accessed data in memory and reduce the load on your database. This means that your users will experience lightning-fast page loading times and smooth and seamless interactions with your platform. Caching is relatively simple to configure and can make a world of difference to your application's performance.

Asynchronous Processing​

The use of asynchronous processing allows multiple tasks (retrieve data from a table, authenticate an ID, load an image) to process at a different time (not in synchrony) from each other, and not block another event. Obviously, removing chronological dependencies from as many tasks as possible can speed overall processing.

Message Queues and Background Processing​

By performing time-consuming or resource-intensive tasks asynchronously, you can create a more efficient and scalable app that won't slow down or crash. Utilize message queues such as RabbitMQ or Apache Kafka (or Redis' native message queueing, like we use here with authentik) along with background processing frameworks like Celery, to offload tasks to separate worker processes or services. Not only will this approach help maintain responsiveness even during peak usage, but it will also help your app scale as your user base grows.

Performance Optimization​

Obviously you should never overlook the importance of optimizing your application, both the code and database queries.

Code and Query Optimization​

By implementing techniques like caching, indexing, and query optimization, you can significantly improve response times and reduce resource usage. And that's not all - by utilizing monitoring and profiling tools, you can identify performance bottlenecks and optimize critical areas of your app for maximum efficiency. Results include faster load times, smoother user experiences, and a more streamlined and effective operation overall.

Fault Tolerance and Resilience​

Planning for failure scenarios and building fault-tolerant systems is a crucial aspect of app development. By implementing redundancy and failover mechanisms, you can ensure that your system remains operational even in the face of unexpected failures or disruptions.

Redundancy and Failover Mechanisms​

In addition to using distributed architectures, as we discussed above, another technique known as redundancy involves replicating data across multiple servers, and/or implementing backup systems. By spreading the workload and data across multiple resources, you eliminate single points of failure and increase system resilience. In the event of a failure, the workload can seamlessly shift to alternative resources, ensuring uninterrupted service.

It is also important to assess potential failure points and plan accordingly. By proactively planning for failure scenarios, you can minimize the impact of outages, avoid data loss, and maintain a smooth user experience. Building a fault-tolerant system is a critical step in creating a reliable app that can withstand unforeseen challenges and provide consistent service to users.

Putting it All Together​

We’ve covered the primary strategies and techniques for building scalable applications, from architecture to asynchronous processing. By incorporating these principles and strategies into the app development process, you can build robust, scalable applications that can handle increased user demand, adapt to growing requirements, and provide a seamless user experience even as the application grows in size and complexity.