puertos/config/routes/nelmio_api_doc.yaml

# Expose your documentation as JSON swagger compliant
app.swagger:
    path: /api/doc.json
    methods: GET
    defaults: { _controller: nelmio_api_doc.controller.swagger }

## Requires the Asset component and the Twig bundle
## $ composer require twig asset
#app.swagger_ui:
#    path: /api/doc
#    methods: GET
#    defaults: { _controller: nelmio_api_doc.controller.swagger_ui }