plugin.c

#include <uwsgi.h>
#include <curl/curl.h>

/*

this is a stats pusher plugin for the datadog server:

--stats-push datadogdb:https://app.datadoghq.com/api/v1/series?api_key=API_KEY

it exports values exposed by the metric subsystem

*/

extern struct uwsgi_server uwsgi;

/*
JSON body:

{"series":[{"metric":"NAME","points":[[NOW,VALUE]],"type":"GAUGE|COUNTER","host":"HOST"}]}

*/

size_t silent_stream_handler(char *ptr, size_t size, size_t nmemb, void *userdata)
{
   return size * nmemb;
}

static void stats_pusher_datadog(struct uwsgi_stats_pusher_instance *uspi, time_t now, char *json, size_t json_len) {

	// we use the same buffer for all of the metrics
	struct uwsgi_buffer *ub = uwsgi_buffer_new(uwsgi.page_size);

	if (uwsgi_buffer_append(ub, "{\"series\":[", 11)) goto error;

	struct uwsgi_metric *um = uwsgi.metrics;
	while(um) {
		uwsgi_rlock(uwsgi.metrics_lock);
		int64_t value = *um->value;
		uwsgi_rwunlock(uwsgi.metrics_lock);

		if (um->reset_after_push){
			uwsgi_wlock(uwsgi.metrics_lock);
			*um->value = um->initial_value;
			uwsgi_rwunlock(uwsgi.metrics_lock);
		}

		if (uwsgi_buffer_append(ub, "{\"metric\":\"", 11)) goto error;
		if (uwsgi_buffer_append_json(ub, um->name, um->name_len)) goto error;
        	if (uwsgi_buffer_append(ub, "\",\"points\":[[", 13)) goto error;
        	if (uwsgi_buffer_num64(ub, now)) goto error;
        	if (uwsgi_buffer_append(ub, ",", 1)) goto error;
        	if (uwsgi_buffer_num64(ub, value)) goto error;
        	if (uwsgi_buffer_append(ub, "]],\"type\":\"", 11)) goto error;
        	if (um->type == UWSGI_METRIC_GAUGE) {
                	if (uwsgi_buffer_append(ub, "gauge", 5)) goto error;
        	}
        	else {
                	if (uwsgi_buffer_append(ub, "counter", 7)) goto error;
        	}
        	if (uwsgi_buffer_append(ub, "\",\"host\":\"", 10)) goto error;
        	if (uwsgi_buffer_append_json(ub, uwsgi.hostname, uwsgi.hostname_len)) goto error;
        	if (uwsgi_buffer_append(ub, "\"}", 2)) goto error;
		if (um->next) {
			if (uwsgi_buffer_append(ub, ",", 1)) goto error;
		}
		um = um->next;
	}

	if (uwsgi_buffer_append(ub, "]}", 2)) goto error;

        // now send the JSON to the datadog server via curl
        CURL *curl = curl_easy_init();
        if (!curl) {
                uwsgi_log_verbose("[datadog] unable to initialize curl\n");
                return;
        }
        struct curl_slist *headers = NULL;
        headers = curl_slist_append(headers, "Content-Type: application/json");
        curl_easy_setopt(curl, CURLOPT_TIMEOUT, uwsgi.socket_timeout);
        curl_easy_setopt(curl, CURLOPT_CONNECTTIMEOUT, uwsgi.socket_timeout);
        curl_easy_setopt(curl, CURLOPT_HTTPHEADER, headers);
        curl_easy_setopt(curl, CURLOPT_URL, uspi->arg);
        curl_easy_setopt(curl, CURLOPT_CUSTOMREQUEST, "POST");
        curl_easy_setopt(curl, CURLOPT_POSTFIELDS, ub->buf);
        curl_easy_setopt(curl, CURLOPT_SSL_VERIFYPEER, 0L);
        curl_easy_setopt(curl, CURLOPT_SSL_VERIFYHOST, 0L);
        curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, &silent_stream_handler);  // disable CURL output to stdout
        CURLcode res = curl_easy_perform(curl);
        curl_slist_free_all(headers);
        if (res != CURLE_OK) {
                uwsgi_log_verbose("[datadog] error sending metrics: %s\n", curl_easy_strerror(res));
                curl_easy_cleanup(curl);
                return;
        }
        long http_code = 0;
#ifdef CURLINFO_RESPONSE_CODE
        curl_easy_getinfo(curl, CURLINFO_RESPONSE_CODE, &http_code);
#else
        curl_easy_getinfo(curl, CURLINFO_HTTP_CODE, &http_code);
#endif
        if (http_code != 200 && http_code != 201 && http_code != 202) {
                uwsgi_log_verbose("[datadog] HTTP api returned non-200 response code: %d\n", (int) http_code);
        }
        curl_easy_cleanup(curl);
	uwsgi_buffer_destroy(ub);
        return;
error:
        uwsgi_log_verbose("[datadog] unable to generate JSON\n");

	uwsgi_buffer_destroy(ub);
}

static void datadog_init(void) {
        struct uwsgi_stats_pusher *usp = uwsgi_register_stats_pusher("datadog", stats_pusher_datadog);
	// we use a custom format not the JSON one
	usp->raw = 1;
}

struct uwsgi_plugin datadog_plugin = {
        .name = "datadog",
        .on_load = datadog_init,
};