3 files changed, 175 insertions, 0 deletions
diff --git a/src/admin/Cargo.toml b/src/admin/Cargo.toml
new file mode 100644
index 00000000..9775b667
--- /dev/null
+++ b/src/admin/Cargo.toml
@@ -0,0 +1,28 @@
+[package]
+name = "garage_admin"
+version = "0.6.0"
+authors = ["Maximilien Richer <code@mricher.fr>"]
+edition = "2018"
+license = "AGPL-3.0"
+description = "Administration and metrics REST HTTP server for Garage"
+repository = "https://git.deuxfleurs.fr/Deuxfleurs/garage"
+
+[lib]
+path = "lib.rs"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+garage_model = { version = "0.6.0", path = "../model" }
+garage_util = { version = "0.6.0", path = "../util" }
+
+futures = "0.3"
+futures-util = "0.3"
+http = "0.2"
+hyper = "0.14"
+log = "0.4"
+
+opentelemetry = "0.17"
+opentelemetry-prometheus = "0.10"
+prometheus = "0.13"
+lazy_static = "1.4"
diff --git a/src/admin/lib.rs b/src/admin/lib.rs
new file mode 100644
index 00000000..443361be
--- /dev/null
+++ b/src/admin/lib.rs
@@ -0,0 +1,6 @@
+//! Crate for handling the admin and metric HTTP APIs
+#[macro_use]
+extern crate log;
+extern crate lazy_static;
+
+pub mod metrics;
diff --git a/src/admin/metrics.rs b/src/admin/metrics.rs
new file mode 100644
index 00000000..547ee4c8
--- /dev/null
+++ b/src/admin/metrics.rs
@@ -0,0 +1,141 @@
+use hyper::{
+	header::CONTENT_TYPE,
+	service::{make_service_fn, service_fn},
+	Body, Method, Request, Response, Server,
+};
+use lazy_static::lazy_static;
+use opentelemetry::{
+	global,
+	metrics::{BoundCounter, BoundValueRecorder},
+	KeyValue,
+};
+use opentelemetry_prometheus::PrometheusExporter;
+use prometheus::{Encoder, TextEncoder};
+use std::convert::Infallible;
+use std::sync::Arc;
+use std::time::SystemTime;
+
+use futures::future::*;
+use garage_model::garage::Garage;
+use garage_util::error::Error as GarageError;
+
+lazy_static! {
+	// This defines the differennt tags that will be referenced by the object
+	static ref HANDLER_ALL: [KeyValue; 1] = [KeyValue::new("handler", "all")];
+}
+
+// serve_req on metric endpoint
+async fn serve_req(
+	req: Request<Body>,
+	admin_server: Arc<AdminServer>,
+) -> Result<Response<Body>, hyper::Error> {
+	println!("Receiving request at path {}", req.uri());
+	let request_start = SystemTime::now();
+
+	admin_server.metrics.http_counter.add(1);
+
+	let response = match (req.method(), req.uri().path()) {
+		(&Method::GET, "/metrics") => {
+			let mut buffer = vec![];
+			let encoder = TextEncoder::new();
+			let metric_families = admin_server.exporter.registry().gather();
+			encoder.encode(&metric_families, &mut buffer).unwrap();
+			admin_server
+				.metrics
+				.http_body_gauge
+				.record(buffer.len() as u64);
+
+			Response::builder()
+				.status(200)
+				.header(CONTENT_TYPE, encoder.format_type())
+				.body(Body::from(buffer))
+				.unwrap()
+		}
+		_ => Response::builder()
+			.status(404)
+			.body(Body::from("Not implemented"))
+			.unwrap(),
+	};
+
+	admin_server
+		.metrics
+		.http_req_histogram
+		.record(request_start.elapsed().map_or(0.0, |d| d.as_secs_f64()));
+	Ok(response)
+}
+
+// AdminServer hold the admin server internal admin_server and the metric exporter
+pub struct AdminServer {
+	exporter: PrometheusExporter,
+	metrics: AdminServerMetrics,
+}
+
+// GarageMetricadmin_server holds the metrics counter definition for Garage
+// FIXME: we would rather have that split up among the different libraries?
+struct AdminServerMetrics {
+	http_counter: BoundCounter<u64>,
+	http_body_gauge: BoundValueRecorder<u64>,
+	http_req_histogram: BoundValueRecorder<f64>,
+	bucket_v2_merkle_updater_todo_queue_length: BoundValueRecorder<f64>,
+}
+
+impl AdminServer {
+	/// init initilialize the AdminServer and background metric server
+	pub fn init() -> AdminServer {
+		let exporter = opentelemetry_prometheus::exporter().init();
+		let meter = global::meter("garage/admin_server");
+		AdminServer {
+			exporter,
+			metrics: AdminServerMetrics {
+				http_counter: meter
+					.u64_counter("router.http_requests_total")
+					.with_description("Total number of HTTP requests made.")
+					.init()
+					.bind(HANDLER_ALL.as_ref()),
+				http_body_gauge: meter
+					.u64_value_recorder("example.http_response_size_bytes")
+					.with_description("The metrics HTTP response sizes in bytes.")
+					.init()
+					.bind(HANDLER_ALL.as_ref()),
+				http_req_histogram: meter
+					.f64_value_recorder("example.http_request_duration_seconds")
+					.with_description("The HTTP request latencies in seconds.")
+					.init()
+					.bind(HANDLER_ALL.as_ref()),
+				bucket_v2_merkle_updater_todo_queue_length: meter
+					.f64_value_recorder("bucket_v2.merkle_updater.todo_queue_length")
+					.with_description("Bucket merkle updater TODO queue length.")
+					.init()
+					.bind(HANDLER_ALL.as_ref()),
+			},
+		}
+	}
+	/// run execute the admin server on the designated HTTP port and listen for requests
+	pub async fn run(
+		self,
+		garage: Arc<Garage>,
+		shutdown_signal: impl Future<Output = ()>,
+	) -> Result<(), GarageError> {
+		let admin_server = Arc::new(self);
+		// For every connection, we must make a `Service` to handle all
+		// incoming HTTP requests on said connection.
+		let make_svc = make_service_fn(move |_conn| {
+			let admin_server = admin_server.clone();
+			// This is the `Service` that will handle the connection.
+			// `service_fn` is a helper to convert a function that
+			// returns a Response into a `Service`.
+			async move {
+				Ok::<_, Infallible>(service_fn(move |req| serve_req(req, admin_server.clone())))
+			}
+		});
+
+		let addr = &garage.config.admin_api.bind_addr;
+
+		let server = Server::bind(&addr).serve(make_svc);
+		let graceful = server.with_graceful_shutdown(shutdown_signal);
+		info!("Admin server listening on http://{}", addr);
+
+		graceful.await?;
+		Ok(())
+	}
+}