Configuration Prometheus (OpenMetrics) Exporter

Now that you have a cache running, you must enable observability features. To this end, you can enable Prometheus exporter. You should allow the Prometheus server without authentication only on locahost or known safe networks.

config.prometheus_address = "127.0.0.1";
config.prometheus_port = 11450;

Alternatively, as in the following example, you can use the EdgePeak route mechanism to set up a route and authenticate before forwarding requests to the localhost-bound Prometheus exporter.

config.prometheus_address = "127.0.0.1";
config.prometheus_port = 8450;
config.upstreams["internal_prometheus"] = {
      .endpoints = {"http://127.0.0.1:8450"}
};
auto& prom = config.vhosts["prom"] = {
      .endpoints = {endpoint(HTTP, 80), endpoint(HTTPS, 443)},
      .pattern = ".*"
};
prom << route(GET|HEAD, "/metrics.*", [](
    client_request req, client_reply rpy) -> future {
      if(req.get_header("Authorization") == "Bearer SecretValue" or req.get_ip() == "192.168.123.45"){
            co_await rpy.set_proxy(req, "internal_prometheus");
      }else{
            co_await rpy.set_error(req, 403);
      }
});