Control API.

Control API.

A new nginx option -l specifies control socket listen address.
The socket is providing an HTTP/1 REST API for retrieving information
about running nginx instance.

Example:

$ nginx -l 127.0.0.1:1234

$ curl 127.0.0.1:1234/1/control/processes | jq
[
  {
    "pid": 41536,
    "name": "worker process",
    "exiting": false
  }
]

Co-authored-by: Roman Arutyunyan <arut@nginx.com>
Co-authored-by: Pavel Pautov <p.pautov@f5.com>
Co-authored-by: Dmitry Plotnikov <d.plotnikov@f5.com>
Co-authored-by: Sergey Kandaurov <pluknet@nginx.com>
Co-authored-by: Ivan Ovchinnikov <i.ovchinnikov@f5.com>