---
title: "How to deploy a Rails app"
description: "Deploy a Rails app to Ample with your coding agent, the CLI or MCP, using build and start commands verified on September 20, 2026."
canonical_url: "https://ample.computer/guides/rails"
last_updated: "2026-09-20"
author: "Ample Computer"
---

# How to deploy a Rails app

Deploy a Rails app to Ample with your coding agent, the CLI or MCP, using build and start commands verified on September 20, 2026.

## The short version

To deploy a Rails app on Ample, run `ample deploy . --name <app-name> --public` in the project directory, or ask your coding agent to deploy it to Ample. Ample builds it on the `ruby-3.4` template, starts it with `bundle exec rails server -b 0.0.0.0 -p $PORT` and returns a public HTTPS URL.

## Deploy Rails

1. **Ask your coding agent.** Install the Ample CLI and create an account, then ask your agent: "Deploy this Rails app to Ample".

   ```sh
   curl -fsSL https://get.ample.computer/install.sh | sh
   ample auth signup
   ```

2. **Or deploy from the CLI.** It waits until the app is live or failed and prints the URL.

   ```sh
   ample deploy . --name <app-name> --public
   ```

3. **Or use MCP.** Call `ample_deploy` on `https://api.ample.computer/mcp` (or `ample mcp` over stdio).
4. **Verify.** On failure read `ample logs <deployment_id> --kind build`, fix the cause and deploy again.

## Tested configuration

| | |
|---|---|
| Template | `ruby-3.4` |
| Install | `bundle config set --local path vendor/bundle && bundle config set --local without 'development test' && bundle install` |
| Start | `bundle exec rails server -b 0.0.0.0 -p $PORT` |
| Tested size | `s-1vcpu-1gb` |

Verified on Rails: the app built and started with the documented commands and answered on its public HTTPS URL. Build and start: bundle install into vendor/bundle from Gemfile.lock (development and test groups skipped), then Puma via `rails server` reading PORT on the ruby-3.4 template with RAILS_ENV=production.

Last verification (2026-09-20): Rails pattern fixture deployed on Ample (bundle install into vendor/bundle from Gemfile.lock (development and test groups skipped), then Puma via `rails server` reading PORT on the ruby-3.4 template with RAILS_ENV=production); for this guide: the app built and started with the documented commands and answered on its public HTTPS URL.

## You need

- A Rails project (bundle install into vendor/bundle from Gemfile.lock (development and test groups skipped), then Puma via `rails server` reading PORT on the ruby-3.4 template with RAILS_ENV=production)
- An Ample account token with servers:write

## Know the limits

- Verified on the ruby-3.4 template at s-1vcpu-1gb; other sizes and Rails major versions are not verified.

## Move a Rails app to Ample

- [How to move a Rails app from AWS EC2 to Ample](https://ample.computer/migrate/aws-ec2-app/rails)
- [How to move a Rails app from DigitalOcean Droplet to Ample](https://ample.computer/migrate/digitalocean-droplet-app/rails)
- [How to move a Rails app from Fly.io to Ample](https://ample.computer/migrate/fly-io-app/rails)
- [How to move a Rails app from Heroku to Ample](https://ample.computer/migrate/heroku-app/rails)
- [How to move a Rails app from Netlify to Ample](https://ample.computer/migrate/netlify-web-app/rails)
- [How to move a Rails app from Railway to Ample](https://ample.computer/migrate/railway-app/rails)
- [How to move a Rails app from Render web service to Ample](https://ample.computer/migrate/render-web-service/rails)
- [How to move a Rails app from Vercel to Ample](https://ample.computer/migrate/vercel-app/rails)

## Frequently asked questions

### Do I need a Dockerfile to deploy Rails?

No. Ample detects Rails from the repository and builds it from source on the `ruby-3.4` template. Dockerfile build steps are not run.

### How do I add a database to a Rails app?

Leave DATABASE_URL unset and deploy: when the code needs Postgres, MySQL, Redis or MongoDB, Ample creates a managed database and passes its connection string to the app. See [Connect Postgres for Rails](https://ample.computer/guides/rails/database-connection).

### What does it cost to host a Rails app on Ample?

The Free plan runs 2 apps at once with no card and a hard monthly budget, so it never bills you. Larger needs are priced on volume; see [pricing](https://ample.computer/pricing).

### What if the deploy fails?

`ample deploy` waits until the app is live or failed. A failure returns who must act, a diagnosis and a suggested fix; read the logs with `ample logs <deployment_id> --kind build`. See [Diagnose deployment failures for Rails](https://ample.computer/guides/rails/deployment-diagnostics).

## More for Rails

- [How to serve Rails public assets through a CDN on Ample](https://ample.computer/guides/rails/cdn-assets): Cdn assets for a Rails app on Ample
- [How to set environment variables and secrets for a Rails app on Ample](https://ample.computer/guides/rails/configuration-secrets): Configuration and secrets for a Rails app on Ample
- [How to connect a Rails app to Postgres on Ample](https://ample.computer/guides/rails/database-connection): Database connection for a Rails app on Ample
- [How to fix a failed Rails deploy on Ample](https://ample.computer/guides/rails/deployment-diagnostics): Deployment diagnostics for a Rails app on Ample
- [How to use S3-compatible storage from a Rails app on Ample](https://ample.computer/guides/rails/object-client): Object storage client for a Rails app on Ample
- [How to serve private files from a Rails app on Ample](https://ample.computer/guides/rails/private-file-access): Private file access for a Rails app on Ample
- [How to run database migrations for a Rails app on Ample](https://ample.computer/guides/rails/schema-changes): Schema changes for a Rails app on Ample