# Apply database schema changes for SvelteKit

## Summary
Apply database schema changes for a SvelteKit app on Ample with a release command. `node migrate.cjs` runs against the injected DATABASE_URL before the new release goes live, and the release fails instead of activating if the migration fails.

## Infrastructure requirements
- Verified (Apps run in isolated x86_64 Firecracker microVMs that auto-pause when idle and wake on request; sizes are the priced VM sizes.)
- Managed PostgreSQL 16 runs in its own microVM and is auto-provisioned when an app needs a database and no DATABASE_URL is supplied.

## Prerequisites
- A migration command that reads DATABASE_URL and exits non-zero on failure
- A PostgreSQL database (supplied or managed)
- An Ample account token with servers:write and databases:read

## Exact tested configuration
- template: `node-22`
- runtime: `node`
- size: `s-1vcpu-1gb`
- install: `npm install`
- build: `npm run build --if-present`
- start: `npm run start`

## Steps
1. **Write an idempotent migration.** Create tables and markers with IF NOT EXISTS or a migration framework so a re-run is safe.
2. **Deploy with the release command.** Ample runs the command before activation; a non-zero exit fails the release.
   
   ```
   ample deploy . --name <app-name> --public --release-command "node migrate.cjs"
   ```
3. **Verify the marker through the app.** Serve a route (/migrated) that reads something only the migration creates.
4. **Verify.** Fetch the live URL and run the success checks below. On failure read the build log, then the runtime log, fix the cause and deploy again; do not blind-retry.
   
   ```
   ample logs <deployment_id> --kind build
   ```

## Tested examples
- **SvelteKit release-command canary**: node migrate.cjs runs before activation against the auto-provisioned managed database.

## Success checks
- migration marker is readable (`/migrated` on the live URL, expect migrated=release-ok)

## Limitations
- Verified on the node-22 template at s-1vcpu-1gb; other templates and sizes are not verified by this recipe.
- 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 managed databases are placed together; cross-node shared databases are unsupported.
- The release command runs once per release on the app VM; there is no separate migration runner or rollback of a partially applied migration.

## Cost estimate
Estimated 10.00 USD per month.
- app server x1 `s-1vcpu-1gb`: 5.00 USD
- managed PostgreSQL database x1 `s-1vcpu-1gb`: 5.00 USD

Apps and managed databases auto-pause when idle; the estimate is the always-on monthly price of the tested sizes. Plan quotas and budgets apply.

## Verification evidence
- canary_run on 2026-09-20T01:42:25Z at revision `199ff1dfd52683832ae75d3f98b53a7a4bff7f96-dirty (CLI e3181f5)`: The same SvelteKit app deployed with --release-command node migrate.cjs; /migrated reported the migration marker. (expires 2027-03-19T01:42:25Z)

Last verified: 2026-09-20T01:42:25Z

## Execution binding
MCP tool `ample_deploy`, schema hash `876465fce906da0c` observed 2026-09-20T01:55:48.667900+00:00 at revision `199ff1dfd526`, binding state `current`, required scopes: servers:write, databases:read.