Larder: a made-up grocery service you can run in one command.

# One Postgres server, one database, and a role and schema per service:
# each service connects as itself and can only touch its own tables.
module postgres "postgres" {
  version = 18
  port    = 5432

  role "orders" { password = "orders" }
  role "payments" { password = "payments" }
  …
  schema "orders" { owner = "orders" }
  schema "payments" { owner = "payments" }
}

$ psql "postgres://orders:orders@postgres.larder.doze:5432/postgres" \
    -c 'select * from identity.users'
ERROR:  permission denied for schema identity

# The topics are the contracts between services, so they are declared here
# rather than created by whichever client happens to write first.
module kafka "kafka" {
  version            = 4
  port               = 9092
  auto_create_topics = false

  topic "users.signed-up" { partitions = 3 }
  topic "orders.placed" { partitions = 3 }
  topic "payments.settled" { partitions = 3 }
  topic "payments.failed" { partitions = 3 }
}

task "migrate-orders" {
  run    = "go run ./platform/cmd/migrate services/orders/migrations"
  inputs = ["services/orders/migrations/*.sql"]
  env    = { DATABASE_URL = "postgres://orders:orders@…" }
}

app "orders" {
  run   = "go run ./services/orders"
  port  = 8003
  ready = http("/healthz")
  after = [task.migrate-orders]
  …
}

defaults {
  sleep = "2m"
  …
}

app "payments" {
  run   = "go run ./services/payments"
  after = [task.migrate-payments]
  sleep = "never"
  …
}

app "orders" {
  …
  sleep = "never" # it consumes Kafka: no request would ever wake it
}

# Dependencies follow the lockfiles: installed again only when one changes.
task "install-fulfilment" {
  dir    = "services/fulfilment"
  run    = "uv sync --frozen"
  inputs = ["pyproject.toml", "uv.lock"]
}

task "install-storefront" {
  dir    = "apps/storefront"
  run    = "bun install --frozen-lockfile"
  inputs = ["package.json", "bun.lock"]
}

# Not in the registry: fetched once, pinned in doze.lock, run from the
# archive. Catches every email; its web UI is the console.
service "mailpit" {
  download = {
    mac = "…/mailpit/releases/download/v1.21.8/mailpit-darwin-arm64.tar.gz"
    …
  }
  port    = 2525
  console = "http://127.0.0.1:8025"
}