# unset-variable

Generated from the code · as of CLI 0.6.0

The CLI prints, for example:

```text
`${TAG}` has no default and is not in the arc's .env. Add it with `omniarc env set TAG`, which asks for the value (or reads it from stdin), or `omniarc env push` for a whole .env, or give it a default (`${TAG:-…}`)
```

Fix it in: `.env`, the arc's environment, which `omniarc env` sets.

**Example: shop/docker-compose.yml**

```yaml
# A small shop: Postgres holds the products, customers and orders, and
# PostgREST serves them as a JSON API on port 3000.
services:
  web:
    image: postgrest/postgrest:v12.2.12
    environment:
      PGRST_DB_URI: postgres://shop:${POSTGRES_PASSWORD:-shop}@db:5432/shop
      PGRST_DB_SCHEMAS: public
      PGRST_DB_ANON_ROLE: web_anon
      PGRST_SERVER_PORT: 3000
    ports: ["3000:3000"]
    depends_on:
      db:
        condition: service_healthy

  db:
    image: postgres:17
    environment:
      POSTGRES_USER: shop
      POSTGRES_DB: shop
      # Set a real one with `omniarc env set POSTGRES_PASSWORD`, which asks for it.
      POSTGRES_PASSWORD: ${POSTGRES_PASSWORD:-shop}
    volumes:
      - db-data:/var/lib/postgresql/data
      - ./db/init.sql:/docker-entrypoint-initdb.d/init.sql:ro
    healthcheck:
      test: ["CMD-SHELL", "pg_isready -U shop -d shop"]
      interval: 5s
      timeout: 5s
      retries: 10

volumes:
  db-data:
```