Kong: DB-less mode loads its whole configuration from one file

# kong.conf
database = off
declarative_config = /etc/kong/kong.yaml

# kong.yaml
_format_version: "3.0"
services:
  - name: billing
    url: http://billing.internal:8080
    routes:
      - name: billing-route
        paths: ["/billing"]
    plugins:
      - name: rate-limiting
        config: { minute: 100, policy: local }

# replace the running config
curl -X POST http://localhost:8001/config -F config=@kong.yaml

# POST /consumers in DB-less mode:
#   HTTP/1.1 405 Method Not Allowed
#
# What it costs: no runtime provisioning, so anything that creates consumers
# or credentials on the fly (a signup flow, OAuth2 token storage) will not work.
#
# What it buys: no database to run or back up, identical config on every node,
# and a start-up that cannot half-apply.