Host form collection with Phoenix: relational workflow state

Deploy a form collection built with Phoenix on Ample using the transactional workflows 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. Verified on Phoenix: an optimistic version check and an event row written in the same transaction, a stale update rejected, and a history query over the application-owned events (history=2 conflict=rejected). Not separately tested: your domain records, validation rules and concurrency policy; treat the form collection-specific behavior as your application code.

Representative Queries

• Host form collection with Phoenix: relational workflow state
• Where can I host Form collection built with Phoenix?
• I need a domain record schema, validation rules and concurrency behavior.

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.

Workflow Steps

1. Build and start
   mix deps.get, MIX_ENV=prod mix compile and mix release in the builder, then the release bin script with PHX_SERVER=true on the elixir-1.18 template; PORT, DATABASE_URL and SECRET_KEY_BASE read in config/runtime.exs. The server must bind 0.0.0.0 on PORT.
2. Implement the pattern on PostgreSQL
   The fixture's module implements transactional workflows: an optimistic version check and an event row written in the same transaction, a stale update rejected, and a history query over the application-owned events (history=2 conflict=rejected). Copy the approach into your schema; keep migrations idempotent and run them with --release-command.
3. 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
4. Verify
   Fetch the live URL and the pattern self-test route(s) (/p/transactional-workflows) from the example; then run your own checks. On failure read ample logs --kind buildthen--kind runtime. Command: ample logs --kind build

Success Checks

• app responds on its public URL
  Kind: http_get
  Path: /
  Expect: ample canary phoenix patterns
• transactional-workflows self-test
  Kind: http_get
  Path: /p/transactional-workflows
  Expect: tx=ok history=2 conflict=rejected

Limitations

• Verified on the elixir-1.18 template at s-1vcpu-1gb with the example fixture; other sizes, templates and Phoenix major versions are not verified.
• The form collection itself (your domain records, validation rules and concurrency policy) 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.
• Managed PostgreSQL 16 only; extensions, connection limits and backup or restore procedures are not verified; apps and their databases are placed together.

Cost Estimate

• Currency: USD
• Monthly Amount: 10.0
  Basis: size prices from pricing.toml (loaded by the API) at build revision 1ac5595375130d45290090e82ed0f554ccd45405-dirty
• Components:
  • app server: size s-1vcpu-1gb, quantity 1.0, monthly amount 5.0
  • managed PostgreSQL database: size 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.

Evidence Summary

• Kind: canary_run
  Summary: Phoenix pattern fixture deployed on Ample; checks passed for transactional-workflows and configuration-secrets. Pattern proof: an optimistic version check and an event row written in the same transaction, a stale update rejected, and a history query over the application-owned events. Observed At: 2026-09-20T23:45:31Z

Formats

• HTML: Link
• Markdown: Link
• JSON: Link