# 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.

## Representative Queries
- Apply database schema changes for SvelteKit
- Where can I host Apply database schema changes built with SvelteKit?
- I need a framework-specific schema migration and rollback procedure; no managed migration service is assumed.

## 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.

## Workflow 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.
   ```bash
   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.
   ```bash
   ample logs <app-name> --kind build
   ```

## Success Checks
- Migration marker is readable:
   - **Kind**: http_get 
   - **Path**: /migrated 
   - **Expect**: migrated=release-ok

## Examples
- **SvelteKit release-command canary**
   Description: `node migrate.cjs` runs before activation against the auto-provisioned managed database.
   Source Ref: `tests/deploy-canaries/sveltekit-postgres-app`

## 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
- **Currency**: USD
- **Monthly Amount**: 10.0
- **Basis**: Size prices from pricing.toml (loaded by the API)
- **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**: 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.

## Evidence Summary
- **Kind**: canary_run
- **Summary**: The same SvelteKit app deployed with --release-command `node migrate.cjs`; /migrated reported the migration marker.
- **Observed At**: 2026-09-20T01:42:25Z
- **Implementation Revision**: 199ff1dfd52683832ae75d3f98b53a7a4bff7f96-dirty (CLI e3181f5)
- **Expires At**: 2027-03-19T01:42:25Z
- **Scope**: cliVersion 0.1.20, platform hosted-beta, template node-22.

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