Disk space report

Report available disk space on nodes and calculate cluster-wide available space in `garage stats` (fix #479)

src/rpc/Cargo.toml

@@ -23,6 +23,7 @@ hex = "0.4"
 tracing = "0.1.30"
 rand = "0.8"
 sodiumoxide = { version = "0.2.5-0", package = "kuska-sodiumoxide" }
+systemstat = "0.2.3"
 
 async-trait = "0.1.7"
 serde = { version = "1.0", default-features = false, features = ["derive", "rc"] }

src/rpc/system.rs

@@ -118,18 +118,28 @@ pub struct System {
 
 	/// Path to metadata directory
 	pub metadata_dir: PathBuf,
+	/// Path to data directory
+	pub data_dir: PathBuf,
 }
 
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct NodeStatus {
 	/// Hostname of the node
 	pub hostname: String,
+
 	/// Replication factor configured on the node
 	pub replication_factor: usize,
 	/// Cluster layout version
 	pub cluster_layout_version: u64,
 	/// Hash of cluster layout staging data
 	pub cluster_layout_staging_hash: Hash,
+
+	/// Disk usage on partition containing metadata directory (tuple: `(avail, total)`)
+	#[serde(default)]
+	pub meta_disk_avail: Option<(u64, u64)>,
+	/// Disk usage on partition containing data directory (tuple: `(avail, total)`)
+	#[serde(default)]
+	pub data_disk_avail: Option<(u64, u64)>,
 }
 
 #[derive(Debug, Clone, Serialize, Deserialize)]
@@ -271,14 +281,8 @@ impl System {
 			}
 		};
 
-		let local_status = NodeStatus {
-			hostname: gethostname::gethostname()
-				.into_string()
-				.unwrap_or_else(|_| "<invalid utf-8>".to_string()),
-			replication_factor,
-			cluster_layout_version: cluster_layout.version,
-			cluster_layout_staging_hash: cluster_layout.staging_hash,
-		};
+		let mut local_status = NodeStatus::initial(replication_factor, &cluster_layout);
+		local_status.update_disk_usage(&config.metadata_dir, &config.data_dir);
 
 		#[cfg(feature = "metrics")]
 		let metrics = SystemMetrics::new(replication_factor);
@@ -379,6 +383,7 @@ impl System {
 			ring,
 			update_ring: Mutex::new(update_ring),
 			metadata_dir: config.metadata_dir.clone(),
+			data_dir: config.data_dir.clone(),
 		});
 		sys.system_endpoint.set_handler(sys.clone());
 		Ok(sys)
@@ -416,12 +421,7 @@ impl System {
 					.get(&n.id.into())
 					.cloned()
 					.map(|(_, st)| st)
-					.unwrap_or(NodeStatus {
-						hostname: "?".to_string(),
-						replication_factor: 0,
-						cluster_layout_version: 0,
-						cluster_layout_staging_hash: Hash::from([0u8; 32]),
-					}),
+					.unwrap_or(NodeStatus::unknown()),
 			})
 			.collect::<Vec<_>>();
 		known_nodes
@@ -600,6 +600,9 @@ impl System {
 		let ring = self.ring.borrow();
 		new_si.cluster_layout_version = ring.layout.version;
 		new_si.cluster_layout_staging_hash = ring.layout.staging_hash;
+
+		new_si.update_disk_usage(&self.metadata_dir, &self.data_dir);
+
 		self.local_status.swap(Arc::new(new_si));
 	}
 
@@ -864,6 +867,48 @@ impl EndpointHandler<SystemRpc> for System {
 	}
 }
 
+impl NodeStatus {
+	fn initial(replication_factor: usize, layout: &ClusterLayout) -> Self {
+		NodeStatus {
+			hostname: gethostname::gethostname()
+				.into_string()
+				.unwrap_or_else(|_| "<invalid utf-8>".to_string()),
+			replication_factor,
+			cluster_layout_version: layout.version,
+			cluster_layout_staging_hash: layout.staging_hash,
+			meta_disk_avail: None,
+			data_disk_avail: None,
+		}
+	}
+
+	fn unknown() -> Self {
+		NodeStatus {
+			hostname: "?".to_string(),
+			replication_factor: 0,
+			cluster_layout_version: 0,
+			cluster_layout_staging_hash: Hash::from([0u8; 32]),
+			meta_disk_avail: None,
+			data_disk_avail: None,
+		}
+	}
+
+	fn update_disk_usage(&mut self, meta_dir: &Path, data_dir: &Path) {
+		use systemstat::{Platform, System};
+		let mounts = System::new().mounts().unwrap_or_default();
+
+		let mount_avail = |path: &Path| {
+			mounts
+				.iter()
+				.filter(|x| path.starts_with(&x.fs_mounted_on))
+				.max_by_key(|x| x.fs_mounted_on.len())
+				.map(|x| (x.avail.as_u64(), x.total.as_u64()))
+		};
+
+		self.meta_disk_avail = mount_avail(meta_dir);
+		self.data_disk_avail = mount_avail(data_dir);
+	}
+}
+
 fn get_default_ip() -> Option<IpAddr> {
 	pnet_datalink::interfaces()
 		.iter()