lighthouse-pulse/beacon_node/rest_api/src/metrics.rs
Luke Anderson 0c1ceab527
Addressed Paul's suggestions.
- Updated some comments.
 - Replaced match statements with map functions.
2019-09-04 13:43:45 +10:00

79 lines
3.0 KiB
Rust

use crate::{success_response, ApiError, ApiResult, DBPath};
use beacon_chain::{BeaconChain, BeaconChainTypes};
use http::HeaderValue;
use hyper::{Body, Request};
use prometheus::{Encoder, TextEncoder};
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 + 'static>(req: Request<Body>) -> ApiResult {
let mut buffer = vec![];
let encoder = TextEncoder::new();
let beacon_chain = req
.extensions()
.get::<Arc<BeaconChain<T>>>()
.ok_or_else(|| ApiError::ServerError("Beacon chain extension missing".to_string()))?;
let db_path = req
.extensions()
.get::<DBPath>()
.ok_or_else(|| ApiError::ServerError("DBPath extension missing".to_string()))?;
// 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);
beacon_chain::scrape_for_metrics(&beacon_chain);
encoder
.encode(&lighthouse_metrics::gather(), &mut buffer)
.unwrap();
String::from_utf8(buffer)
.map(|string| {
let mut response = success_response(Body::from(string));
// Need to change the header to text/plain for prometheus
response.headers_mut().insert(
"content-type",
HeaderValue::from_static("text/plain; charset=utf-8"),
);
response
})
.map_err(|e| ApiError::ServerError(format!("Failed to encode prometheus info: {:?}", e)))
}