page:recipes:digital downloads:rails:download delivery

Host digital downloads with Rails: authorized file delivery

Deploy a digital downloads built with Rails on Ample using the generated downloads 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: an export query rendered to a CSV artifact stored with metadata in a private bucket and returned only to an authorized caller (401 without token, export=ok rows=3). Not separately tested: your export formats, retention policy and entitlement model; treat the digital downloads-specific behavior as your application code.

Representative Queries

• Host digital downloads with Rails: authorized file delivery
• Where can I host Digital downloads built with Rails?
• I need a file entitlement model and an application-enforced download authorization flow.

Resource Requirements

• primitive:compute
• primitive:postgres
• primitive:s3-compatible-object-storage

Infrastructure Requirements

1. Compute
   Summary: Apps run in isolated x86_64 Firecracker microVMs that auto-pause when idle and wake on request; sizes are the priced VM sizes.
2. Postgres
   Summary: Managed PostgreSQL 16 runs in its own microVM and is auto-provisioned when an app needs a database and no DATABASE_URL is supplied.
3. S3-compatible object storage
   Summary: Buckets are S3-compatible with issued credentials; PutObject and GetObject are verified by canary. Other S3 operations are not verified.

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. Implement the pattern on PostgreSQL
   The fixture's module implements generated downloads: an export query rendered to a CSV artifact stored with metadata in a private bucket and returned only to an authorized caller (401 without token, export=ok rows=3). Copy the approach into your schema; keep migrations idempotent and run them with --release-command.
3. Wire object storage
   Create the bucket(s), then pass endpoint, region, bucket and keys as --env values. Use path-style addressing. Keep private data in an unpublished bucket.
4. Deploy
   Run the synchronous deploy once and read the result (exit 0 live, 1 failed, 2 blocked). Re-running with no change is a no-op. Command: ample deploy . --name --public --env S3_ENDPOINT=... --env S3_REGION=... --env S3_BUCKET=... --env S3_ACCESS_KEY_ID=... --env S3_SECRET_ACCESS_KEY=...
5. Verify
   Fetch the live URL and the pattern self-test route(s) (/p/generated-downloads) from the example; then run your own checks. On failure read ample logs --kind build then --kind runtime. Command: ample logs --kind build

Limitations

• Verified on the ruby-3.4 template at s-1vcpu-1gb with the example fixture; other sizes, templates and Rails major versions are not verified.
• The digital downloads itself (your export formats, retention policy and entitlement model) is application code and was not separately tested; the pattern checks are what was verified.
• Region, compliance attestations and request-duration limits are unknown and not claimed.
• Apps auto-pause when idle and wake on the next request; always-on is an operator setting, not a plan feature.

Success Checks

• App responds on its public URL
  Expected Output: ample canary rails patterns
• Generated-downloads self-test
  Expected Output: export=ok rows=3 (with ?token=...; 401 without)

Cost Estimate

• Currency: USD
• Monthly Amount: $10.00
• Basis: Size prices from pricing.toml (loaded by the API) at build revision 1ac5595375130d45290090e82ed0f554ccd45405-dirty
• Components:
  1. App server: s-1vcpu-1gb, quantity: 1.0, monthly amount: 5.0
  2. Managed PostgreSQL database: s-1vcpu-1gb, quantity: 1.0, monthly amount: 5.0
• Note: Always-on monthly price of the tested sizes; apps and databases auto-pause when idle. Buckets are allocation-priced per quota and not included.

Next Actions

1. Browse the catalog index
   • Method: GET
   • Path: /v1/catalog
2. Search published recipes by intent, stack and constraints
   • Method: POST
   • Path: /v1/catalog/search
   • Body: { "limit": 5, "query": "Host digital downloads with Rails: authorized file delivery" }
3. Prepare a side-effect-free deployment plan for an authorized project
   • Method: POST
   • Path: /v1/catalog/plan
   • Body: { "inputs": {}, "projectId": "", "recipeId": "page:recipes:digital-downloads:rails:download-delivery", "recipeRevision": "r1" }
4. Read the existing agent authentication setup
   • Method: GET
   • Path: /mcp/setup