5 files changed, 193 insertions, 0 deletions
diff --git a/src/api/Cargo.toml b/src/api/Cargo.toml
index 29b26e5e..db77cf38 100644
--- a/src/api/Cargo.toml
+++ b/src/api/Cargo.toml
@@ -54,6 +54,9 @@ quick-xml = { version = "0.21", features = [ "serialize" ] }
 url = "2.1"
 
 opentelemetry = "0.17"
+opentelemetry-prometheus = "0.10"
+opentelemetry-otlp = "0.10"
+prometheus = "0.13"
 
 [features]
 k2v = [ "garage_util/k2v", "garage_model/k2v" ]
diff --git a/src/api/admin/api_server.rs b/src/api/admin/api_server.rs
new file mode 100644
index 00000000..836b5158
--- /dev/null
+++ b/src/api/admin/api_server.rs
@@ -0,0 +1,128 @@
+use std::sync::Arc;
+
+use async_trait::async_trait;
+
+use futures::future::Future;
+use http::header::CONTENT_TYPE;
+use hyper::{Body, Request, Response};
+
+use opentelemetry::trace::{SpanRef, Tracer};
+use opentelemetry_prometheus::PrometheusExporter;
+use prometheus::{Encoder, TextEncoder};
+
+use garage_model::garage::Garage;
+use garage_util::error::Error as GarageError;
+
+use crate::error::*;
+use crate::generic_server::*;
+
+use crate::admin::router::{Authorization, Endpoint};
+
+pub struct AdminApiServer {
+	garage: Arc<Garage>,
+	exporter: PrometheusExporter,
+	metrics_token: Option<String>,
+	admin_token: Option<String>,
+}
+
+impl AdminApiServer {
+	pub fn new(garage: Arc<Garage>) -> Self {
+		let exporter = opentelemetry_prometheus::exporter().init();
+		let cfg = &garage.config.admin;
+		let metrics_token = cfg
+			.metrics_token
+			.as_ref()
+			.map(|tok| format!("Bearer {}", tok));
+		let admin_token = cfg
+			.admin_token
+			.as_ref()
+			.map(|tok| format!("Bearer {}", tok));
+		Self {
+			garage,
+			exporter,
+			metrics_token,
+			admin_token,
+		}
+	}
+
+	pub async fn run(self, shutdown_signal: impl Future<Output = ()>) -> Result<(), GarageError> {
+		if let Some(bind_addr) = self.garage.config.admin.api_bind_addr {
+			let region = self.garage.config.s3_api.s3_region.clone();
+			ApiServer::new(region, self)
+				.run_server(bind_addr, shutdown_signal)
+				.await
+		} else {
+			Ok(())
+		}
+	}
+
+	fn handle_metrics(&self) -> Result<Response<Body>, Error> {
+		let mut buffer = vec![];
+		let encoder = TextEncoder::new();
+
+		let tracer = opentelemetry::global::tracer("garage");
+		let metric_families = tracer.in_span("admin/gather_metrics", |_| {
+			self.exporter.registry().gather()
+		});
+
+		encoder
+			.encode(&metric_families, &mut buffer)
+			.ok_or_internal_error("Could not serialize metrics")?;
+
+		Ok(Response::builder()
+			.status(200)
+			.header(CONTENT_TYPE, encoder.format_type())
+			.body(Body::from(buffer))?)
+	}
+}
+
+#[async_trait]
+impl ApiHandler for AdminApiServer {
+	const API_NAME: &'static str = "admin";
+	const API_NAME_DISPLAY: &'static str = "Admin";
+
+	type Endpoint = Endpoint;
+
+	fn parse_endpoint(&self, req: &Request<Body>) -> Result<Endpoint, Error> {
+		Endpoint::from_request(req)
+	}
+
+	async fn handle(
+		&self,
+		req: Request<Body>,
+		endpoint: Endpoint,
+	) -> Result<Response<Body>, Error> {
+		let expected_auth_header = match endpoint.authorization_type() {
+			Authorization::MetricsToken => self.metrics_token.as_ref(),
+			Authorization::AdminToken => self.admin_token.as_ref(),
+		};
+
+		if let Some(h) = expected_auth_header {
+			match req.headers().get("Authorization") {
+				None => Err(Error::Forbidden(
+					"Authorization token must be provided".into(),
+				)),
+				Some(v) if v.to_str().map(|hv| hv == h).unwrap_or(false) => Ok(()),
+				_ => Err(Error::Forbidden(
+					"Invalid authorization token provided".into(),
+				)),
+			}?;
+		}
+
+		match endpoint {
+			Endpoint::Metrics => self.handle_metrics(),
+			_ => Err(Error::NotImplemented(format!(
+				"Admin endpoint {} not implemented yet",
+				endpoint.name()
+			))),
+		}
+	}
+}
+
+impl ApiEndpoint for Endpoint {
+	fn name(&self) -> &'static str {
+		Endpoint::name(self)
+	}
+
+	fn add_span_attributes(&self, _span: SpanRef<'_>) {}
+}
diff --git a/src/api/admin/mod.rs b/src/api/admin/mod.rs
new file mode 100644
index 00000000..ff2cf4b1
--- /dev/null
+++ b/src/api/admin/mod.rs
@@ -0,0 +1,2 @@
+pub mod api_server;
+mod router;
diff --git a/src/api/admin/router.rs b/src/api/admin/router.rs
new file mode 100644
index 00000000..d0b30fc1
--- /dev/null
+++ b/src/api/admin/router.rs
@@ -0,0 +1,59 @@
+use crate::error::*;
+
+use hyper::{Method, Request};
+
+use crate::router_macros::router_match;
+
+pub enum Authorization {
+	MetricsToken,
+	AdminToken,
+}
+
+router_match! {@func
+
+/// List of all Admin API endpoints.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum Endpoint {
+	Metrics,
+	Options,
+	GetClusterStatus,
+	GetClusterLayout,
+	UpdateClusterLayout,
+	ApplyClusterLayout,
+	RevertClusterLayout,
+}}
+
+impl Endpoint {
+	/// Determine which S3 endpoint a request is for using the request, and a bucket which was
+	/// possibly extracted from the Host header.
+	/// Returns Self plus bucket name, if endpoint is not Endpoint::ListBuckets
+	pub fn from_request<T>(req: &Request<T>) -> Result<Self, Error> {
+		let path = req.uri().path();
+
+		use Endpoint::*;
+		let res = match (req.method(), path) {
+			(&Method::OPTIONS, _) => Options,
+			(&Method::GET, "/metrics") => Metrics,
+			(&Method::GET, "/status") => GetClusterStatus,
+			(&Method::GET, "/layout") => GetClusterLayout,
+			(&Method::POST, "/layout") => UpdateClusterLayout,
+			(&Method::POST, "/layout/apply") => ApplyClusterLayout,
+			(&Method::POST, "/layout/revert") => RevertClusterLayout,
+			(m, p) => {
+				return Err(Error::BadRequest(format!(
+					"Unknown API endpoint: {} {}",
+					m, p
+				)))
+			}
+		};
+
+		Ok(res)
+	}
+	/// Get the kind of authorization which is required to perform the operation.
+	pub fn authorization_type(&self) -> Authorization {
+		match self {
+			Self::Metrics => Authorization::MetricsToken,
+			_ => Authorization::AdminToken,
+		}
+	}
+}
diff --git a/src/api/lib.rs b/src/api/lib.rs
index 0078f7b5..5c522799 100644
--- a/src/api/lib.rs
+++ b/src/api/lib.rs
@@ -12,6 +12,7 @@ mod router_macros;
 /// This mode is public only to help testing. Don't expect stability here
 pub mod signature;
 
+pub mod admin;
 #[cfg(feature = "k2v")]
 pub mod k2v;
 pub mod s3;