lighthouse-pulse/beacon_node/rest_api/src/metrics.rs
Michael Sproul 5e7803f00b Clean up database metrics, add freezer DB size (#715)
* Clean up database metrics, add freezer DB size

* Address review comments
2019-12-13 13:30:58 +11:00

68 lines
2.6 KiB
Rust

use crate::response_builder::ResponseBuilder;
use crate::{ApiError, ApiResult};
use beacon_chain::{BeaconChain, BeaconChainTypes};
use hyper::{Body, Request};
use lighthouse_metrics::{Encoder, TextEncoder};
use std::path::PathBuf;
use std::sync::Arc;
pub use lighthouse_metrics::*;
lazy_static! {
pub static ref REQUEST_RESPONSE_TIME: Result<Histogram> = try_create_histogram(
"http_server_request_duration_seconds",
"Time taken to build a response to a HTTP request"
);
pub static ref REQUEST_COUNT: Result<IntCounter> = try_create_int_counter(
"http_server_request_total",
"Total count of HTTP requests received"
);
pub static ref SUCCESS_COUNT: Result<IntCounter> = try_create_int_counter(
"http_server_success_total",
"Total count of HTTP 200 responses sent"
);
}
/// Returns the full set of Prometheus metrics for the Beacon Node application.
///
/// # Note
///
/// This is a HTTP handler method.
pub fn get_prometheus<T: BeaconChainTypes>(
req: Request<Body>,
beacon_chain: Arc<BeaconChain<T>>,
db_path: PathBuf,
freezer_db_path: PathBuf,
) -> ApiResult {
let mut buffer = vec![];
let encoder = TextEncoder::new();
// There are two categories of metrics:
//
// - Dynamically updated: things like histograms and event counters that are updated on the
// fly.
// - Statically updated: things which are only updated at the time of the scrape (used where we
// can avoid cluttering up code with metrics calls).
//
// The `lighthouse_metrics` crate has a `DEFAULT_REGISTRY` global singleton (via `lazy_static`)
// which keeps the state of all the metrics. Dynamically updated things will already be
// up-to-date in the registry (because they update themselves) however statically updated
// things need to be "scraped".
//
// We proceed by, first updating all the static metrics using `scrape_for_metrics(..)`. Then,
// using `lighthouse_metrics::gather(..)` to collect the global `DEFAULT_REGISTRY` metrics into
// a string that can be returned via HTTP.
slot_clock::scrape_for_metrics::<T::EthSpec, T::SlotClock>(&beacon_chain.slot_clock);
store::scrape_for_metrics(&db_path, &freezer_db_path);
beacon_chain::scrape_for_metrics(&beacon_chain);
encoder
.encode(&lighthouse_metrics::gather(), &mut buffer)
.unwrap();
String::from_utf8(buffer)
.map(|string| ResponseBuilder::new(&req)?.body_text(string))
.map_err(|e| ApiError::ServerError(format!("Failed to encode prometheus info: {:?}", e)))?
}