## Host CSV Import Tool with Rails: File Attachments

### Summary
Deploy a CSV import tool built with Rails on Ample using the browser file uploads pattern. Compute runs the app in an isolated microVM behind a public HTTPS URL, a managed PostgreSQL 16 database is auto-provisioned and injected as DATABASE_URL, a private S3-compatible bucket holds objects with credentials delivered as encrypted environment variables. Verified on Rails: content-type and size validation that rejects disallowed files, an object written to a private bucket and a row linking the record to the object key (reject=ok upload=ok linked=ok). Not separately tested: your upload UI, allowed types, size limits and virus scanning; treat the CSV import tool-specific behavior as your application code.

### Representative Queries
- Host CSV import tool with Rails: file attachments
- Where can I host a CSV import tool built with Rails?
- I need a restricted upload flow, file validation and record-to-object linkage.

### Resource Requirements
- Compute
- PostgreSQL
- S3-compatible object storage

### 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.
- **S3-compatible object storage**: Buckets are S3-compatible with issued credentials; PutObject and GetObject are verified by canary. Other S3 operations are not verified.

### Prerequisites
1. A Rails project that builds and starts with the documented commands (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).
2. A PostgreSQL driver reading DATABASE_URL at runtime (auto-provisioned when omitted, or supplied with --env).
3. A bucket from `ample bucket create` with its credentials passed as encrypted S3_* environment variables.
4. An Ample account token with `servers:write`, `databases:read`, `buckets:read`.

### Tested Configuration
- Template: ruby-3.4
- Runtime: ruby
- Size: s-1vcpu-1gb
- 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`

### Workflow Steps
1. **Build and start**: Install dependencies and start server with production settings.
2. **Implement the pattern on PostgreSQL**: Ensure content-type and size validation is in place and maintain idempotency in migrations.
3. **Wire object storage**: Create buckets and set up environment variables for endpoint and credentials.
4. **Deploy**: Run a synchronous deploy and check the result.
5. **Verify**: Fetch the live URL and run self-tests to confirm functionality.

### Examples
- **Rails Pattern Fixture**: Multi-pattern Rails app whose browser file uploads module was checked live.

### Success Checks
- App responds on its public URL.
- Browser-file-uploads self-test completes successfully.

### Limitations
- Verified only on ruby-3.4 template with the example fixture; other setups may not perform as verified.
- Application-specific behavior such as upload UI needs independent testing.

### Cost Estimate
- **Monthly Amount**: $10.00 (based on tested sizes and services)
- **Components**: App server and managed PostgreSQL database, each at $5.00 monthly.