## Connect Postgres for Rails

### Summary
Database connection for a Rails app on Ample. Verified on Rails: a managed PostgreSQL database auto-provisioned and injected as DATABASE_URL, with real queries succeeding at request time (records=ok). 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.

### Representative Queries
- Connect Postgres for Rails
- Where can I host Connect Postgres built with Rails?
- I need driver setup, connection settings, secret handling and a real connection test.

### Resource Requirements
- primitive:compute
- primitive:postgres

### Infrastructure Requirements
- **Compute**: Apps run in isolated x86_64 Firecracker microVMs that auto-pause when idle and wake on request; sizes are the priced VM sizes.
- **Postgres**: Managed PostgreSQL 16 runs in its own microVM and is auto-provisioned when an app needs a database and no DATABASE_URL is supplied.

### Prerequisites
- 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)
- A PostgreSQL driver reading DATABASE_URL at runtime
- An Ample account token with servers:write, databases:read

### Workflow Steps
1. **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; the server must bind 0.0.0.0 on PORT.
2. **Read DATABASE_URL at runtime**: Open connections from the environment inside handlers or a pool; omit DATABASE_URL to auto-provision a managed database or pass --env DATABASE_URL=... for an existing one.
3. **Verify**: Fetch the live URL and /p/relational-records on the example; on failure read the build and runtime logs. Command: ample logs --kind build

### Limitations
- Verified on the ruby-3.4 template at s-1vcpu-1gb; other sizes and Rails major versions are not verified.
- Region, compliance attestations and request-duration limits are unknown and not claimed.
- Managed PostgreSQL 16 only; extensions, connection limits and backup or restore procedures are not verified.

### Success Checks
- **App responds on its public URL**: HTTP GET `/` expects response: ample canary rails patterns
- **Relational-records check from the example**: HTTP GET `/p/relational-records` expects to see the pattern fixture checks.

### Cost Estimate
- **Currency**: USD
- **Monthly Amount**: 10.0
- **Components**:
  - App server: s-1vcpu-1gb - 1.0 - $5.0/month
  - Managed PostgreSQL database: s-1vcpu-1gb - 1.0 - $5.0/month
- **Note**: Always-on monthly price of the tested sizes; apps auto-pause when idle. Buckets are allocation-priced per quota and not included.

### Examples
- **Rails pattern fixture**: Verified database connection on Rails. Source: tests/deploy-canaries/rails-patterns.

### Additional Information
- **Last Verified At**: 2026-09-20T21:55:28Z
- **MCP Binding**: Current
- **Unknowns**: Region availability and compliance attestations are unknown; none are claimed.
- **Formats**:
  - HTML: [Link](/content/guides/rails/database-connection/index.html)
  - Markdown: [Link](/content/guides/rails/database-connection.md)
  - JSON: [Link](https://api.ample.computer/v1/catalog/recipes/page%3Aguides%3Arails%3Adatabase-connection)