page:guides:rails:private file access

Enforce private-file authorization for Rails

Summary

Private file access for a Rails app on Ample. Verified on Rails: a role-to-document access model with negative tests (401, 403) and an authorized private-bucket round-trip (private=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

• Enforce private-file authorization for Rails
• Where can I host Enforce private-file authorization built with Rails?
• I need application identity integration, per-file access rules and negative authorization tests.

Resource Requirements

• primitive:compute
• primitive:postgres
• primitive: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

• 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
• A bucket from ample bucket create with credentials passed as encrypted S3_* environment variables
• An Ample account token with servers:write, databases:read, buckets: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. Create the bucket and pass its credentials: Create it once with ample bucket create, then pass endpoint, region, bucket and keys with --env; use path-style addressing.
   • Command: ample deploy . --name --public --env S3_ENDPOINT=... --env S3_REGION=... --env S3_BUCKET=... --env S3_ACCESS_KEY_ID=... --env S3_SECRET_ACCESS_KEY=...
3. Authorize before touching storage: Return 401 for unauthenticated requests and 403 for the wrong role; keep the bucket unpublished and stream objects through the app.
4. Verify: Fetch the live URL and /p/private-document-library on the example; on failure read the build and runtime logs.
   • Command: ample logs --kind build

Examples

• Rails pattern fixture: Verified private file access on Rails.
  • Source Ref: tests/deploy-canaries/rails-patterns

Success Checks

• App responds on its public URL
  • Kind: http_get
  • Path: /
  • Expect: ample canary rails patterns
• Private-document-library check from the example
  • Kind: http_get
  • Path: /p/private-document-library
  • Expect: see the pattern fixture checks

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.
• PutObject and GetObject with path-style addressing are verified; other S3 operations are not.