## Host appointment booking with Rails: relational workflow state

### Summary
Deploy a appointment booking built with Rails 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 Rails: 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 appointment booking-specific behavior as your application code.

### Representative Queries
- Host appointment booking with Rails: relational workflow state
- Where can I host Appointment booking built with Rails?
- 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.

### Framework
Rails

### Workload
Appointment booking

### Release Status
published

### Support Status
verified

### Execution Status
ready

### Prerequisites
- 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)
- A PostgreSQL driver reading DATABASE_URL at runtime (auto-provisioned when omitted, or supplied with --env)
- An Ample account token with servers:write, databases: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**: `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 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.
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 build` then `--kind runtime`.

### Examples
- **Rails pattern fixture**: Multi-pattern Rails app whose transactional workflows module was checked live; the module is under tests/deploy-canaries/_pattern-modules.

### Success Checks
- **App responds on its public URL**: `http_get` to `/` expects `ample canary rails patterns`
- **Transactional-workflows self-test**: `http_get` to `/p/transactional-workflows` expects `tx=ok history=2 conflict=rejected`

### 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 appointment booking 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
- **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.