page:guides:phoenix:schema changes

Apply Database Schema Changes for Phoenix

Summary

Schema changes for a Phoenix app on Ample. Verified on Phoenix: a --release-command migration ran before activation and its marker was readable by the live app (migrated=release-ok). 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.

Representative Queries

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

Resource Requirements

• Compute
• Postgres

Infrastructure Requirements

1. Compute

   • Status: verified
   • Summary: Apps run in isolated x86_64 Firecracker microVMs that auto-pause when idle and wake on request; sizes are the priced VM sizes.

2. Postgres

   • Status: verified
   • Summary: 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 Phoenix project (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).
• A PostgreSQL driver reading DATABASE_URL at runtime.
• An Ample account token with servers:write, databases:read.

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.

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.
   • Command: ample deploy . --name --public --release-command "python3 migrate.py"

3. Verify

   • Fetch the live URL and /p/migrated on the example; on failure read the build and runtime logs.
   • Command: ample logs --kind build

Examples

• Phoenix Pattern Fixture
  Verified schema changes on Phoenix.

Success Checks

1. App Responds on Its Public URL

   • Kind: http_get
   • Path: /
   • Expect: ample canary phoenix patterns

2. Migrated Check from the Example

   • Kind: http_get
   • Path: /p/migrated
   • Expect: see the pattern fixture checks

Limitations

• Verified on the elixir-1.18 template at s-1vcpu-1gb; other sizes and Phoenix major versions are not verified.
• Region, compliance attestations and request-duration limits are unknown and not claimed.
• Managed PostgreSQL 16 only; extensions, connection limits and backup or restore procedures are not verified.

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 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.
  Observed At: 2026-09-20T23:45:31Z
  Implementation Revision: 4d1511e574302f3904b75088bd4048a0975218b3-dirty (CLI 0.1.21)
  Expires At: 2027-03-19T23:45:31Z

Next Actions

1. Browse the Catalog Index

   • Action ID: browse-catalog
   • Method: GET
   • Relative Path: /v1/catalog

2. Search Published Recipes by Intent, Stack and Constraints

   • Action ID: search-recipes
   • Method: POST
   • Relative Path: /v1/catalog/search
   • Parameters: { "body": { "limit": 5, "query": "Apply database schema changes for Phoenix" } }

3. Prepare a Side-Effect-Free Deployment Plan

   • Action ID: plan:page:guides:phoenix:schema-changes
   • Method: POST
   • Relative Path: /v1/catalog/plan
   • Parameters: { "body": { "inputs": {}, "projectId": "", "recipeId": "page:guides:phoenix:schema-changes", "recipeRevision": "r1" } }

4. Read the Existing Agent Authentication Setup

   • Action ID: auth-setup
   • Method: GET
   • Relative Path: /mcp/setup

5. Browse Phoenix

   • Action ID: browse:stack:framework-phoenix
   • Method: GET
   • Relative Path: /v1/catalog/nodes/stack%3Aframework-phoenix