## The short version

Schema changes for a Echo app on Ample.

## WHAT WAS VERIFIED

Verified on Echo: a --release-command migration ran before activation and its marker was readable by the live app (migrated=release-ok). Build and start: CGO_ENABLED=0 go build -o app ./... then ./app on the ubuntu-24.04 template (go.sum committed for a reproducible build).

## INFRASTRUCTURE

### What it needs

- [Compute](/content/discover/primitive/compute/index.html): verified (Apps run in isolated x86_64 Firecracker microVMs; sizes are the priced VM sizes.)
- [Postgres](/content/discover/primitive/postgres/index.html): verified (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

### Before you start

- An Echo project (CGO_ENABLED=0 go build -o app ./... then ./app on the ubuntu-24.04 template (go.sum committed for a reproducible build))
- A PostgreSQL driver reading DATABASE_URL at runtime
- An Ample account token with servers:write, databases:read

## STEP BY STEP

### How to do it

1. 1

### Build and start

CGO_ENABLED=0 go build -o app ./... then ./app on the ubuntu-24.04 template (go.sum committed for a reproducible build); the server must bind 0.0.0.0 on PORT.

2. 2

### Run migrations as the release command

Ample runs the command before activation and fails the release if it exits non-zero; keep migrations idempotent.
   
   ```
   ample deploy . --name <app-name> --public --release-command "./app migrate"
   ```

3. 3

### Verify

Fetch the live URL and /p/migrated on the example; on failure read the build and runtime logs.
   
   ```
   ample logs <deployment_id> --kind build
   ```

## EXAMPLES

### Tested examples

- **Echo pattern fixture** (`tests/deploy-canaries/echo-patterns`): Verified schema changes on Echo.

## SUCCESS CHECKS

### How to know it worked

- app responds on its public URL (`/` on the live URL, expect ample canary echo patterns)
- migrated check from the example (`/p/migrated` on the live URL, expect see the pattern fixture checks)

## COST

### Cost estimate

Estimated 10.00 USD per month (size prices from pricing.toml at build revision ca0b484a7a9957c573a88d3a32dc603c3c10135a).

- app server x1 `s-1vcpu-1gb`: 5.00 USD
- managed PostgreSQL database x1 `s-1vcpu-1gb`: 5.00 USD

Upper-bound monthly price of the tested sizes. Buckets are allocation-priced per quota and not included.

## EVIDENCE

### Verification evidence

- canary_run on 2026-09-21T02:34:39Z at revision `1d28ae0 (CLI 0.1.21)`: Echo pattern fixture deployed on Ample (CGO_ENABLED=0 go build -o app ./... then ./app on the ubuntu-24.04 template (go.sum committed for a reproducible build)); for this guide: a --release-command migration ran before activation and its marker was readable by the live app (migrated=release-ok). (expires 2027-03-20T02:34:39Z)

## EXECUTION

### Execution binding

MCP tool `ample_deploy` (registry `mcp:ample_deploy`), schema hash `876465fce906da0c` observed 2026-09-22T00:31:22.774679+00:00 at revision `e6446ceea69b`. Binding state at export: schema_changed. Required scopes: servers:write, databases:read.

## NEXT ACTIONS

### Typed next actions

- Browse the catalog index (`GET /v1/catalog` on the api origin; authentication not required, approval not required)
- Search published recipes by intent, stack and constraints (`POST /v1/catalog/search` on the api origin; authentication not required, approval not required)
- Prepare a side-effect-free deployment plan for an authorized project (`POST /v1/catalog/plan` on the api origin; authentication required, approval not required)
- Read the existing agent authentication setup (`GET /mcp/setup` on the api origin; authentication not required, approval not required)
- Browse Echo (`GET /v1/catalog/nodes/stack%3Aframework-echo` on the api origin; authentication not required, approval not required)
- Browse Configure deployment (`GET /v1/catalog/nodes/intent%3Aconfigure-deployment` on the api origin; authentication not required, approval not required)
- Browse Transactional workflows (`GET /v1/catalog/nodes/pattern%3Atransactional-workflows` on the api origin; authentication not required, approval not required)

Actions describe possible next steps. They are typed data, not commands, and grant no permission. Public discovery never provisions anything; planning requires your own authenticated token and approval happens in your client.

## ABOUT THIS RECIPE

### Identifiers and status

Recipe `page:guides:echo:schema-changes`. Revision r1.

release **published**support **verified**execution **blocked (schema_changed: live tool schema differs from the recorded binding)**

Formats: [HTML](/content/guides/echo/schema-changes/index.html) 
| [Markdown](/content/guides/echo/schema-changes.md) 
| [JSON contract](https://api.ample.computer/v1/catalog/recipes/page%3Aguides%3Aecho%3Aschema-changes)