page:recipes:csv import tool:rails:attachments

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.