Deploying Rails Apps on AWS Elastic Beanstalk: An Expert Guide

As a full-stack developer who has worked with Ruby on Rails for nearly a decade, I‘ve deployed my fair share of Rails apps. In the early days, I would spin up a VPS on Slicehost or Linode, install Linux, Nginx, Passenger, MySQL, and deploy my app manually. It was a time-consuming process that required ongoing maintenance and scaling effort.

Then Heroku came along and revolutionized Rails deployment. With a simple git push, you could now deploy your app and let Heroku worry about managing servers, databases and scaling. Heroku was a game-changer in terms of developer productivity and lowered the barrier to entry.

But for some apps, Heroku isn‘t the right choice. You may need more control over your infrastructure, more advanced scaling and monitoring, or the ability to use other AWS services. That‘s where AWS Elastic Beanstalk comes in.

What is Elastic Beanstalk?

Elastic Beanstalk is a fully-managed platform-as-a-service (PaaS) from Amazon Web Services that makes it easy to deploy, run, and scale web applications. It supports popular languages and frameworks like Ruby, Node.js, Python, Java, .NET, PHP, and Go.

Under the hood, Elastic Beanstalk uses familiar AWS services like EC2, S3, ELB, and Auto Scaling to provision infrastructure and manage your application stack. But you don‘t have to interact with those services directly.

Instead, you simply provide your application code and configuration settings, and Elastic Beanstalk takes care of provisioning instances, load balancing, auto-scaling, monitoring, and deployment. It abstracts away the underlying infrastructure so you can focus on writing code.

Here‘s a basic diagram of the Elastic Beanstalk architecture:

(Image source: AWS Docs)

Elastic Beanstalk has several key components:

• Application – A logical collection of components, including environments, versions, and environment configurations.
• Environment – An application version deployed to AWS resources. You can have multiple environments (prod, staging, dev, etc) per application. Each environment runs on its own set of instances.
• Environment Tier – Specifies if the environment handles web requests or background jobs. The web server tier uses ELB and runs your app on EC2. The worker tier pulls tasks from an SQS queue.
• Environment Configuration – Defines how an environment and its associated resources behave, including EC2 instance type, ELB settings, Auto Scaling rules, and more.
• Application Version – A specific labeled iteration of deployable code. Each version points to an artifact (e.g. a source bundle in S3) and a Dockerfile or Procfile that specifies how to deploy it.

Elastic Beanstalk for Rails Apps

So why use Elastic Beanstalk for Rails apps specifically? There are several compelling reasons:

1. Easy to get started – Deploying a Rails app to Elastic Beanstalk is straightforward. You can use the EB CLI to create a new environment in minutes, provide your code, and let Elastic Beanstalk handle the rest. Compared to configuring servers manually, it‘s far simpler.

2. Fully managed infrastructure – AWS manages the underlying infrastructure that runs your app. You don‘t have to worry about OS patches, security updates, monitoring, etc. Just focus on your app code. There‘s even a managed database service (Amazon RDS) that you can enable with a single command.

3. Autoscaling and Load Balancing – Elastic Beanstalk can automatically scale your app in response to traffic and load. You can define thresholds for CPU, memory, or request latency which trigger adding or removing EC2 instances. The Elastic Load Balancer distributes traffic across all the instances. This means you get high availability and can handle demand spikes without over-provisioning resources.

4. Flexible configuration – While Elastic Beanstalk has reasonable defaults, you can customize and control almost every aspect of your app‘s environment. This includes instance types, environment variables, security groups, database settings, load balancer behavior, logging, and more. This lets you optimize your environment for your particular app‘s needs.

5. Multiple Environments – Elastic Beanstalk lets you create separate environments for production, staging, QA, and development. Each environment is isolated with its own settings and resources. This makes it easy to test changes before promoting them to production. You can also do Blue-Green deployments to minimize downtime.

6. VPC Support – You can run Elastic Beanstalk in a private Virtual Private Cloud (VPC) for added security. This lets you control network access to your instances with custom subnets, NACLs, and security groups. You can even integrate with on-premises resources via VPN or DirectConnect.

7. Integration with other AWS services – Elastic Beanstalk is just one service in the broader AWS ecosystem. You can seamlessly leverage and integrate with other services that are useful for Rails apps:

   • Store session state and cache data in ElastiCache
   • Process background jobs with SQS and Elastic Beanstalk Worker
   • Handle asynchronous tasks and event-driven workflows with Lambda
   • Manage secrets with Parameter Store and KMS
   • Analyze logs and monitor app metrics with CloudWatch

8. Customize with containers – In addition to running Rails in its "legacy" runtime, you can also deploy your app as a Docker container on Elastic Beanstalk. This gives you complete control over your application stack, including native dependencies, language versions, and OS libraries. It also lets you develop and test with the same container images locally and in production.

Getting Started

The basic steps to deploying a Rails app on Elastic Beanstalk are:

1. Initialize your EB application
2. Launch an environment
3. Configure your database
4. Set environment variables and production settings
5. Deploy your app version
6. Configure load balancing, autoscaling, monitoring, etc.

I‘ve already covered these in detail earlier in the guide, so I won‘t repeat them here. The key things to remember are:

• Use eb init to create the initial EB config
• Use eb create to launch a new environment and specify the stack
• Don‘t store secrets in your codebase, use environment variables instead
• Read the Rails production checklist for other important config
• Set RAILS_SERVE_STATIC_FILES=true so Rails serves assets directly
• Use Rolling or Blue-Green deployment policy for zero downtime deploys

Elastic Beanstalk vs Alternatives

So how does Elastic Beanstalk compare to other options for deploying Rails apps? Let‘s look at a few common alternatives:

Heroku

Heroku is a popular PaaS for deploying Rails apps. It‘s known for its simplicity, developer experience, and ecosystem of add-on services. Heroku manages all the infrastructure details for you. It supports easy scaling, has good deployment tools, and a large community.

However, Heroku can be quite expensive, especially as you scale up. It has limited customization options and you‘re constrained to 512MB slug sizes unless you use monorepos. You also can‘t easily leverage AWS-specific services and features.

DigitalOcean

DigitalOcean provides simple virtual private servers (Droplets) which you can use to deploy Rails apps. They have good performance for the price and an easy to use control panel and API. You get complete control over your instances and can configure them as you wish.

The downside is that you have to manage the server yourself, including security updates, packages, and dependencies. You‘ll also need to set up your own load balancing, monitoring, and scaling. It can be a good fit for small apps, side projects, or those on a budget.

Docker

Increasingly, Rails devs are deploying their apps as Docker containers. This has some benefits – it isolates your app‘s dependencies, provides consistency across environments, and you can develop and test locally in the same configuration. With Docker templates and services like Convox, it‘s not too hard.

But orchestrating containers in production still requires some extra work. You‘ll need a way to provision hosts, network the containers, handle service discovery, configure storage and secrets, etc. Tools like Kubernetes, ECS, and Fargate can help, but have their own learning curve compared to PaaS options.

Bare Metal / VPS

The traditional approach of provisioning your own servers, either on bare metal or virtual private servers, is still viable for some use cases. If you have a dedicated Ops team, stricter compliance and security needs, or require specialized hardware, it can make sense.

But for most Rails devs, managing your own infrastructure is a big distraction from product development. Unless you have a compelling reason to do so, I don‘t recommend it. Use a platform or tooling that automates the undifferentiated heavy lifting of infrastructure.

Costs

Of course, a big factor in evaluating deployment options is the cost. Elastic Beanstalk itself is free – you only pay for the underlying AWS resources you use. This includes:

• EC2 instances
• EBS volumes
• S3 storage
• Data transfer
• ELB load balancers
• RDS databases

AWS has a pricing calculator you can use to estimate your monthly bill based on your expected usage. In general, Elastic Beanstalk can be quite cost effective, especially compared to Heroku.

A single t2.micro instance (1 CPU, 1 GB RAM) is $8.50/month. The RDS db.t2.micro database is free for a year. If you run a small app with moderate traffic, you can likely operate for less than $20/month, even with multiple environments. As you scale up, the savings vs Heroku become more pronounced.

Conclusion

If you already use AWS services, or need more control than Heroku provides, Elastic Beanstalk is a compelling way to deploy Rails apps on AWS. It provides automation and abstractions over infrastructure, while still giving you full control over the underlying resources when you need it.

In this guide, we‘ve covered the key concepts, trade-offs, and steps to get your Rails app running on Elastic Beanstalk. We discussed configuration, environments, databases, deployments, and costs. And we compared it to alternative deployment options.

Hopefully you now have a solid understanding of how to use Elastic Beanstalk effectively for your Rails apps. The AWS documentation and community are great resources to dive deeper. Or let me know if you have any other questions!

As a full-stack Rails developer, I‘ve come to appreciate the power and flexibility of Elastic Beanstalk. It lets me focus on building features, while still giving me the ability to tweak the lower-level details when needed. Give it a try for your next project.