## The short version

Database connection for a Phoenix app on Ample.

## WHAT WAS VERIFIED

Verified on Phoenix: a managed PostgreSQL database auto-provisioned and injected as DATABASE_URL, with real queries succeeding at request time (records=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.

## 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

- 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

## STEP BY STEP

### How to do it

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; the server must bind 0.0.0.0 on PORT.

2. **Read DATABASE_URL at runtime**  
   Open connections from the environment inside handlers or a pool; omit DATABASE_URL to auto-provision a managed database or pass --env DATABASE_URL=... for an existing one.

3. **Verify**  
   Fetch the live URL and /p/relational-records on the example; on failure read the build and runtime logs.
   
   ```
   ample logs <deployment_id> --kind build
   ```

## EXAMPLES

### Tested examples

- **Phoenix pattern fixture** (`tests/deploy-canaries/phoenix-patterns`): Verified database connection on Phoenix.

## SUCCESS CHECKS

### How to know it worked

- app responds on its public URL (`/` on the live URL, expect ample canary phoenix patterns)
- relational-records check from the example (`/p/relational-records` 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 2026-09-20T23:45:31Z at revision `4d1511e574302f3904b75088bd4048a0975218b3 (CLI 0.1.21)`: Phoenix pattern fixture deployed on Ample (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); for this guide: a managed PostgreSQL database auto-provisioned and injected as DATABASE_URL, with real queries succeeding at request time (records=ok). (expires 2027-03-19T23:45:31Z)

## 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 Phoenix (`GET /v1/catalog/nodes/stack%3Aframework-phoenix` on the api origin; authentication not required, approval not required)
- Browse Connect app to database (`GET /v1/catalog/nodes/intent%3Aconnect-app-to-database` on the api origin; authentication not required, approval not required)
- Browse Relational records (`GET /v1/catalog/nodes/pattern%3Arelational-records` 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:phoenix:database-connection`. Revision r1.

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