summary endpoint to existing web server about prometheus-cpp

[jupp0r]

Yes, you'll have to implement some glue logic. It'll basically work like the Exposer that prometheus-cpp comes with already and I'd encourage you to look at the code here: https://github.com/jupp0r/prometheus-cpp/tree/master/pull/src

The rough flow is as follows:

1. Your existing http server gets a request on a metrics endpoint (url).
2. You get a copy of the current metrics state from a registry via the Collect() method
3. You use the text serializer to render the metrics to prometheus' text format
4. You set a bunch of response headers for your response (see the exposer code or prometheus docs)
5. Send the response and cross fingers

Let me know how that goes.

[benitogf]

Send the response and cross fingers
😄

Thanks for your kind response, I did exactly that, using only src/core was enough to setup the endpoint. Here's the endpoint handler as a reference in case that someone else needs to do something similar:

#pragma once
#include "seasocks/PageHandler.h"
#include "prometheus/registry.h"
#include "prometheus/serializer.h"
#include "prometheus/text_serializer.h"

using std::shared_ptr;
using seasocks::PageHandler;
using seasocks::Response;
using seasocks::Request;
using prometheus::Registry;
using prometheus::Serializer;
using prometheus::TextSerializer;

class MetricsHandler: public PageHandler {
 private:
  shared_ptr<Registry> metrics;
 public:
  explicit MetricsHandler(shared_ptr<Registry> metrics_registry):
    metrics(metrics_registry) {}
  virtual std::shared_ptr<Response> handle(const Request& request) {
    auto serializer = std::unique_ptr<Serializer>{new TextSerializer()};
    if (request.verb() == Request::Verb::Get &&
        request.getRequestUri() == "/metrics") {
      return Response::textResponse(
        serializer->Serialize(metrics.get()->Collect()));
    }
    return Response::unhandled();
  }
};

[yaminisridaran]

I have a existing http server already running. I need to expose a metrics rest api and how to get the metrics to be sent to this metrics api.
Any pointers to some sample code for handling this situation.

[jupp0r]

@yaminisridaran see the example code and verbal explanation above.