caddy.json

{
  "apps": {
    "http": {
      "servers": {
        "server_0": {
          "listen": [
            ":80"
          ],
          "logs": {},
          "routes": [
            {
              "match": [
                {
                  "host": [
                    "0.0.0.0"
                  ]
                }
              ]
            },
            {
              "handle": [
                {
                  "handler": "reverse_proxy",
                  "buffer_requests": true,
                  "upstreams": [
                    {
                      "dial": "localhost:8000"
                    }
                  ],
                  "headers": {
                    "response": {
                      "add": {
                        "Response-Time": ["{http.request.duration}"],
                        "Proxy-Latency": ["{http.reverse_proxy.upstream.latency}"]
                      }
                    }
                  }
                }
              ]
            }
          ]
        }
      }
    }
  }
}