Expose health status over RPC (#6274)

* Node-health to a separate crate. * Initialize node_health outside of dapps. * Expose health over RPC. * Bring back 412 and fix JS. * Add health to workspace and tests. * Fix compilation without default features. * Fix borked merge. * Revert to generics to avoid virtual calls. * Fix node-health tests. * Add missing trailing comma.
2017-08-28 14:11:55 +02:00 · 2017-08-28 14:11:55 +02:00 · 3226e1ca33
commit 3226e1ca33
parent 622632616c
31 changed files with 513 additions and 300 deletions
--- a/Cargo.lock
+++ b/Cargo.lock
@ -1613,6 +1613,21 @@ dependencies = [
 "ws2_32-sys 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
 ]

+[[package]]
+name = "node-health"
+version = "0.1.0"
+dependencies = [
+ "futures 0.1.11 (registry+https://github.com/rust-lang/crates.io-index)",
+ "futures-cpupool 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
+ "log 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
+ "ntp 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "parity-reactor 0.1.0",
+ "parking_lot 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde 1.0.9 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde_derive 1.0.9 (registry+https://github.com/rust-lang/crates.io-index)",
+ "time 0.1.35 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "nodrop"
 version = "0.1.9"
@ -1821,6 +1836,7 @@ dependencies = [
 "isatty 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
 "jsonrpc-core 7.0.0 (git+https://github.com/paritytech/jsonrpc.git?branch=parity-1.7)",
 "log 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
+ "node-health 0.1.0",
 "num_cpus 1.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
 "number_prefix 0.2.5 (registry+https://github.com/rust-lang/crates.io-index)",
 "panic_hook 0.1.0",
@ -1862,7 +1878,6 @@ dependencies = [
 "ethcore-util 1.8.0",
 "fetch 0.1.0",
 "futures 0.1.11 (registry+https://github.com/rust-lang/crates.io-index)",
- "futures-cpupool 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
 "itertools 0.5.9 (registry+https://github.com/rust-lang/crates.io-index)",
 "jsonrpc-core 7.0.0 (git+https://github.com/paritytech/jsonrpc.git?branch=parity-1.7)",
 "jsonrpc-http-server 7.0.0 (git+https://github.com/paritytech/jsonrpc.git?branch=parity-1.7)",
@ -1870,7 +1885,7 @@ dependencies = [
 "log 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
 "mime 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
 "mime_guess 1.6.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "ntp 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "node-health 0.1.0",
 "parity-dapps-glue 1.7.0 (registry+https://github.com/rust-lang/crates.io-index)",
 "parity-hash-fetch 1.8.0",
 "parity-reactor 0.1.0",
@ -1985,6 +2000,7 @@ dependencies = [
 "jsonrpc-ws-server 7.0.0 (git+https://github.com/paritytech/jsonrpc.git?branch=parity-1.7)",
 "log 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
 "multihash 0.6.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "node-health 0.1.0",
 "order-stat 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
 "parity-reactor 0.1.0",
 "parity-updater 1.8.0",
--- a/Cargo.toml
+++ b/Cargo.toml
@ -43,6 +43,7 @@ ethcore-logger = { path = "logger" }
 ethcore-stratum = { path = "stratum" }
 ethcore-network = { path = "util/network" }
 ethkey = { path = "ethkey" }
+node-health = { path = "dapps/node-health" }
 rlp = { path = "util/rlp" }
 rpc-cli = { path = "rpc_cli" }
 parity-hash-fetch = { path = "hash-fetch" }
@ -110,4 +111,4 @@ lto = false
 panic = "abort"

 [workspace]
-members = ["ethstore/cli", "ethkey/cli", "evmbin", "whisper", "chainspec"]
+members = ["ethstore/cli", "ethkey/cli", "evmbin", "whisper", "chainspec", "dapps/node-health"]
--- a/dapps/Cargo.toml
+++ b/dapps/Cargo.toml
@ -9,15 +9,12 @@ authors = ["Parity Technologies <admin@parity.io>"]

 [dependencies]
 base32 = "0.3"
-env_logger = "0.4"
 futures = "0.1"
-futures-cpupool = "0.1"
 linked-hash-map = "0.3"
 log = "0.3"
 parity-dapps-glue = "1.7"
 mime = "0.2"
 mime_guess = "1.6.1"
-ntp = "0.2.0"
 rand = "0.3"
 rustc-hex = "1.0"
 serde = "1.0"
@ -32,15 +29,19 @@ itertools = "0.5"
 jsonrpc-core = { git = "https://github.com/paritytech/jsonrpc.git", branch = "parity-1.7" }
 jsonrpc-http-server = { git = "https://github.com/paritytech/jsonrpc.git", branch = "parity-1.7" }

-ethcore-devtools = { path = "../devtools" }
 ethcore-util = { path = "../util" }
 fetch = { path = "../util/fetch" }
+node-health = { path = "./node-health" }
 parity-hash-fetch = { path = "../hash-fetch" }
 parity-reactor = { path = "../util/reactor" }
 parity-ui = { path = "./ui" }

 clippy = { version = "0.0.103", optional = true}

+[dev-dependencies]
+env_logger = "0.4"
+ethcore-devtools = { path = "../devtools" }
+
 [features]
 dev = ["clippy", "ethcore-util/dev"]

--- a/dapps/node-health/Cargo.toml
+++ b/dapps/node-health/Cargo.toml
@ -0,0 +1,18 @@
+[package]
+name = "node-health"
+description = "Node's health status"
+version = "0.1.0"
+license = "GPL-3.0"
+authors = ["Parity Technologies <admin@parity.io>"]
+
+[dependencies]
+futures = "0.1"
+futures-cpupool = "0.1"
+log = "0.3"
+ntp = "0.2.0"
+parking_lot = "0.4"
+serde = "1.0"
+serde_derive = "1.0"
+time = "0.1.35"
+
+parity-reactor = { path = "../../util/reactor" }
--- a/dapps/node-health/src/health.rs
+++ b/dapps/node-health/src/health.rs
@ -0,0 +1,122 @@
+// Copyright 2015-2017 Parity Technologies (UK) Ltd.
+// This file is part of Parity.
+
+// Parity is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Parity is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Parity.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Reporting node's health.
+
+use std::sync::Arc;
+use std::time;
+use futures::{Future, BoxFuture};
+use futures::sync::oneshot;
+use types::{HealthInfo, HealthStatus, Health};
+use time::{TimeChecker, MAX_DRIFT};
+use parity_reactor::Remote;
+use parking_lot::Mutex;
+use {SyncStatus};
+
+const TIMEOUT_SECS: u64 = 5;
+const PROOF: &str = "Only one closure is invoked.";
+
+/// A struct enabling you to query for node's health.
+#[derive(Debug, Clone)]
+pub struct NodeHealth {
+	sync_status: Arc<SyncStatus>,
+	time: TimeChecker,
+	remote: Remote,
+}
+
+impl NodeHealth {
+	/// Creates new `NodeHealth`.
+	pub fn new(sync_status: Arc<SyncStatus>, time: TimeChecker, remote: Remote) -> Self {
+		NodeHealth { sync_status, time, remote, }
+	}
+
+	/// Query latest health report.
+	pub fn health(&self) -> BoxFuture<Health, ()> {
+		trace!(target: "dapps", "Checking node health.");
+		// Check timediff
+		let sync_status = self.sync_status.clone();
+		let time = self.time.time_drift();
+		let (tx, rx) = oneshot::channel();
+		let tx = Arc::new(Mutex::new(Some(tx)));
+		let tx2 = tx.clone();
+		self.remote.spawn_with_timeout(
+			move || time.then(move |result| {
+				let _ = tx.lock().take().expect(PROOF).send(Ok(result));
+				Ok(())
+			}),
+			time::Duration::from_secs(TIMEOUT_SECS),
+			move || {
+				let _ = tx2.lock().take().expect(PROOF).send(Err(()));
+			},
+		);
+
+		rx.map_err(|err| {
+			warn!(target: "dapps", "Health request cancelled: {:?}", err);
+		}).and_then(move |time| {
+			// Check peers
+			let peers = {
+				let (connected, max) = sync_status.peers();
+				let (status, message) = match connected {
+					0 => {
+						(HealthStatus::Bad, "You are not connected to any peers. There is most likely some network issue. Fix connectivity.".into())
+					},
+					1 => (HealthStatus::NeedsAttention, "You are connected to only one peer. Your node might not be reliable. Check your network connection.".into()),
+					_ => (HealthStatus::Ok, "".into()),
+				};
+				HealthInfo { status, message, details: (connected, max) }
+			};
+
+			// Check sync
+			let sync = {
+				let is_syncing = sync_status.is_major_importing();
+				let (status, message) = if is_syncing {
+					(HealthStatus::NeedsAttention, "Your node is still syncing, the values you see might be outdated. Wait until it's fully synced.".into())
+				} else {
+					(HealthStatus::Ok, "".into())
+				};
+				HealthInfo { status, message, details: is_syncing }
+			};
+
+			// Check time
+			let time = {
+				let (status, message, details) = match time {
+					Ok(Ok(diff)) if diff < MAX_DRIFT && diff > -MAX_DRIFT => {
+						(HealthStatus::Ok, "".into(), diff)
+					},
+					Ok(Ok(diff)) => {
+						(HealthStatus::Bad, format!(
+							"Your clock is not in sync. Detected difference is too big for the protocol to work: {}ms. Synchronize your clock.",
+							diff,
+						), diff)
+					},
+					Ok(Err(err)) => {
+						(HealthStatus::NeedsAttention, format!(
+							"Unable to reach time API: {}. Make sure that your clock is synchronized.",
+							err,
+						), 0)
+					},
+					Err(_) => {
+						(HealthStatus::NeedsAttention, "Time API request timed out. Make sure that the clock is synchronized.".into(), 0)
+					},
+				};
+
+				HealthInfo { status, message, details, }
+			};
+
+			Ok(Health { peers, sync, time})
+		}).boxed()
+	}
+}
--- a/dapps/node-health/src/lib.rs
+++ b/dapps/node-health/src/lib.rs
@ -0,0 +1,49 @@
+// Copyright 2015-2017 Parity Technologies (UK) Ltd.
+// This file is part of Parity.
+
+// Parity is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Parity is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Parity.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Node Health status reporting.
+
+#![warn(missing_docs)]
+
+extern crate futures;
+extern crate futures_cpupool;
+extern crate ntp;
+extern crate time as time_crate;
+extern crate parity_reactor;
+extern crate parking_lot;
+
+#[macro_use]
+extern crate log;
+#[macro_use]
+extern crate serde_derive;
+
+mod health;
+mod time;
+mod types;
+
+pub use futures_cpupool::CpuPool;
+pub use health::NodeHealth;
+pub use types::{Health, HealthInfo, HealthStatus};
+pub use time::{TimeChecker, Error};
+
+/// Indicates sync status
+pub trait SyncStatus: ::std::fmt::Debug + Send + Sync {
+	/// Returns true if there is a major sync happening.
+	fn is_major_importing(&self) -> bool;
+
+	/// Returns number of connected and ideal peers.
+	fn peers(&self) -> (usize, usize);
+}
--- a/dapps/node-health/src/time.rs
+++ b/dapps/node-health/src/time.rs
@ -41,8 +41,8 @@ use futures::{self, Future, BoxFuture};
 use futures::future::{self, IntoFuture};
 use futures_cpupool::{CpuPool, CpuFuture};
 use ntp;
-use time::{Duration, Timespec};
-use util::RwLock;
+use parking_lot::RwLock;
+use time_crate::{Duration, Timespec};

 /// Time checker error.
 #[derive(Debug, Clone, PartialEq)]
@ -164,7 +164,7 @@ impl Ntp for SimpleNtp {

 				match ntp::request(&server.address) {
 					Ok(packet) => {
-						let dest_time = ::time::now_utc().to_timespec();
+						let dest_time = ::time_crate::now_utc().to_timespec();
 						let orig_time = Timespec::from(packet.orig_time);
 						let recv_time = Timespec::from(packet.recv_time);
 						let transmit_time = Timespec::from(packet.transmit_time);
@ -293,7 +293,7 @@ mod tests {
 	use time::Duration;
 	use futures::{future, Future};
 	use super::{Ntp, TimeChecker, Error};
-	use util::RwLock;
+	use parking_lot::RwLock;

 	#[derive(Clone)]
 	struct FakeNtp(RefCell<Vec<Duration>>, Cell<u64>);
--- a/dapps/node-health/src/types.rs
+++ b/dapps/node-health/src/types.rs
@ -0,0 +1,57 @@
+// Copyright 2015-2017 Parity Technologies (UK) Ltd.
+// This file is part of Parity.
+
+// Parity is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Parity is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Parity.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Base health types.
+
+/// Health API endpoint status.
+#[derive(Debug, PartialEq, Serialize)]
+pub enum HealthStatus {
+	/// Everything's OK.
+	#[serde(rename = "ok")]
+	Ok,
+	/// Node health need attention
+	/// (the issue is not critical, but may need investigation)
+	#[serde(rename = "needsAttention")]
+	NeedsAttention,
+	/// There is something bad detected with the node.
+	#[serde(rename = "bad")]
+	Bad,
+}
+
+/// Represents a single check in node health.
+/// Cointains the status of that check and apropriate message and details.
+#[derive(Debug, PartialEq, Serialize)]
+#[serde(deny_unknown_fields)]
+pub struct HealthInfo<T> {
+	/// Check status.
+	pub status: HealthStatus,
+	/// Human-readable message.
+	pub message: String,
+	/// Technical details of the check.
+	pub details: T,
+}
+
+/// Node Health status.
+#[derive(Debug, PartialEq, Serialize)]
+#[serde(deny_unknown_fields)]
+pub struct Health {
+	/// Status of peers.
+	pub peers: HealthInfo<(usize, usize)>,
+	/// Sync status.
+	pub sync: HealthInfo<bool>,
+	/// Time diff info.
+	pub time: HealthInfo<i64>,
+}
--- a/dapps/src/api/api.rs
+++ b/dapps/src/api/api.rs
@ -21,32 +21,28 @@ use hyper::method::Method;
 use hyper::status::StatusCode;

 use api::{response, types};
-use api::time::{TimeChecker, MAX_DRIFT};
 use apps::fetcher::Fetcher;
 use handlers::{self, extract_url};
 use endpoint::{Endpoint, Handler, EndpointPath};
+use node_health::{NodeHealth, HealthStatus, Health};
 use parity_reactor::Remote;
-use {SyncStatus};

 #[derive(Clone)]
 pub struct RestApi {
 	fetcher: Arc<Fetcher>,
-	sync_status: Arc<SyncStatus>,
-	time: TimeChecker,
+	health: NodeHealth,
 	remote: Remote,
 }

 impl RestApi {
 	pub fn new(
 		fetcher: Arc<Fetcher>,
-		sync_status: Arc<SyncStatus>,
-		time: TimeChecker,
+		health: NodeHealth,
 		remote: Remote,
 	) -> Box<Endpoint> {
 		Box::new(RestApi {
 			fetcher,
-			sync_status,
-			time,
+			health,
 			remote,
 		})
 	}
@ -90,68 +86,23 @@ impl RestApiRouter {
 	}

 	fn health(&self, control: Control) -> Box<Handler> {
-		use self::types::{HealthInfo, HealthStatus, Health};
-
-		trace!(target: "dapps", "Checking node health.");
-		// Check timediff
-		let sync_status = self.api.sync_status.clone();
-		let map = move |time| {
-			// Check peers
-			let peers = {
-				let (connected, max) = sync_status.peers();
-				let (status, message) = match connected {
-					0 => {
-						(HealthStatus::Bad, "You are not connected to any peers. There is most likely some network issue. Fix connectivity.".into())
-					},
-					1 => (HealthStatus::NeedsAttention, "You are connected to only one peer. Your node might not be reliable. Check your network connection.".into()),
-					_ => (HealthStatus::Ok, "".into()),
-				};
-				HealthInfo { status, message, details: (connected, max) }
+		let map = move |health: Result<Result<Health, ()>, ()>| {
+			let status = match health {
+				Ok(Ok(ref health)) => {
+					if [&health.peers.status, &health.sync.status].iter().any(|x| *x != &HealthStatus::Ok) {
+						StatusCode::PreconditionFailed // HTTP 412
+					} else {
+						StatusCode::Ok // HTTP 200
+					}
+				},
+				_ => StatusCode::ServiceUnavailable, // HTTP 503
 			};

-			// Check sync
-			let sync = {
-				let is_syncing = sync_status.is_major_importing();
-				let (status, message) = if is_syncing {
-					(HealthStatus::NeedsAttention, "Your node is still syncing, the values you see might be outdated. Wait until it's fully synced.".into())
-				} else {
-					(HealthStatus::Ok, "".into())
-				};
-				HealthInfo { status, message, details: is_syncing }
-			};
-
-			// Check time
-			let time = {
-				let (status, message, details) = match time {
-					Ok(Ok(diff)) if diff < MAX_DRIFT && diff > -MAX_DRIFT => {
-						(HealthStatus::Ok, "".into(), diff)
-					},
-					Ok(Ok(diff)) => {
-						(HealthStatus::Bad, format!(
-							"Your clock is not in sync. Detected difference is too big for the protocol to work: {}ms. Synchronize your clock.",
-							diff,
-						), diff)
-					},
-					Ok(Err(err)) => {
-						(HealthStatus::NeedsAttention, format!(
-							"Unable to reach time API: {}. Make sure that your clock is synchronized.",
-							err,
-						), 0)
-					},
-					Err(_) => {
-						(HealthStatus::NeedsAttention, "Time API request timed out. Make sure that the clock is synchronized.".into(), 0)
-					},
-				};
-
-				HealthInfo { status, message, details, }
-			};
-
-			response::as_json(StatusCode::Ok, &Health { peers, sync, time })
+			response::as_json(status, &health)
 		};
-
-		let time = self.api.time.time_drift();
+		let health = self.api.health.health();
 		let remote = self.api.remote.clone();
-		Box::new(handlers::AsyncHandler::new(time, map, remote, control))
+		Box::new(handlers::AsyncHandler::new(health, map, remote, control))
 	}
 }

--- a/dapps/src/api/mod.rs
+++ b/dapps/src/api/mod.rs
@ -18,8 +18,6 @@

 mod api;
 mod response;
-mod time;
 mod types;

 pub use self::api::RestApi;
-pub use self::time::TimeChecker;
--- a/dapps/src/api/types.rs
+++ b/dapps/src/api/types.rs
@ -25,43 +25,3 @@ pub struct ApiError {
 	/// More technical error details.
 	pub detail: String,
 }
-
-/// Health API endpoint status.
-#[derive(Debug, PartialEq, Serialize)]
-pub enum HealthStatus {
-	/// Everything's OK.
-	#[serde(rename = "ok")]
-	Ok,
-	/// Node health need attention
-	/// (the issue is not critical, but may need investigation)
-	#[serde(rename = "needsAttention")]
-	NeedsAttention,
-	/// There is something bad detected with the node.
-	#[serde(rename = "bad")]
-	Bad
-}
-
-/// Represents a single check in node health.
-/// Cointains the status of that check and apropriate message and details.
-#[derive(Debug, PartialEq, Serialize)]
-#[serde(deny_unknown_fields)]
-pub struct HealthInfo<T> {
-	/// Check status.
-	pub status: HealthStatus,
-	/// Human-readable message.
-	pub message: String,
-	/// Technical details of the check.
-	pub details: T,
-}
-
-/// Node Health status.
-#[derive(Debug, PartialEq, Serialize)]
-#[serde(deny_unknown_fields)]
-pub struct Health {
-	/// Status of peers.
-	pub peers: HealthInfo<(usize, usize)>,
-	/// Sync status.
-	pub sync: HealthInfo<bool>,
-	/// Time diff info.
-	pub time: HealthInfo<i64>,
-}
--- a/dapps/src/apps/fetcher/mod.rs
+++ b/dapps/src/apps/fetcher/mod.rs
@ -281,6 +281,7 @@ mod tests {
 		}
 	}

+	#[derive(Debug)]
 	struct FakeSync(bool);
 	impl SyncStatus for FakeSync {
 		fn is_major_importing(&self) -> bool { self.0 }
--- a/dapps/src/lib.rs
+++ b/dapps/src/lib.rs
@ -21,11 +21,9 @@

 extern crate base32;
 extern crate futures;
-extern crate futures_cpupool;
 extern crate itertools;
 extern crate linked_hash_map;
 extern crate mime_guess;
-extern crate ntp;
 extern crate rand;
 extern crate rustc_hex;
 extern crate serde;
@ -40,6 +38,7 @@ extern crate jsonrpc_http_server;

 extern crate ethcore_util as util;
 extern crate fetch;
+extern crate node_health;
 extern crate parity_dapps_glue as parity_dapps;
 extern crate parity_hash_fetch as hash_fetch;
 extern crate parity_reactor;
@ -57,7 +56,6 @@ extern crate ethcore_devtools as devtools;
 #[cfg(test)]
 extern crate env_logger;

-
 mod endpoint;
 mod apps;
 mod page;
@ -79,19 +77,12 @@ use util::RwLock;
 use jsonrpc_http_server::{self as http, hyper, Origin};

 use fetch::Fetch;
-use futures_cpupool::CpuPool;
+use node_health::NodeHealth;
 use parity_reactor::Remote;

 pub use hash_fetch::urlhint::ContractClient;
+pub use node_health::SyncStatus;

-/// Indicates sync status
-pub trait SyncStatus: Send + Sync {
-	/// Returns true if there is a major sync happening.
-	fn is_major_importing(&self) -> bool;
-
-	/// Returns number of connected and ideal peers.
-	fn peers(&self) -> (usize, usize);
-}

 /// Validates Web Proxy tokens
 pub trait WebProxyTokens: Send + Sync {
@ -156,8 +147,7 @@ impl Middleware {

 	/// Creates new middleware for UI server.
 	pub fn ui<F: Fetch>(
-		ntp_servers: &[String],
-		pool: CpuPool,
+		health: NodeHealth,
 		remote: Remote,
 		dapps_domain: &str,
 		registrar: Arc<ContractClient>,
@ -172,11 +162,9 @@ impl Middleware {
 		).embeddable_on(None).allow_dapps(false));
 		let special = {
 			let mut special = special_endpoints(
-				ntp_servers,
-				pool,
+				health,
 				content_fetcher.clone(),
 				remote.clone(),
-				sync_status.clone(),
 			);
 			special.insert(router::SpecialEndpoint::Home, Some(apps::ui()));
 			special
@ -197,8 +185,7 @@ impl Middleware {

 	/// Creates new Dapps server middleware.
 	pub fn dapps<F: Fetch>(
-		ntp_servers: &[String],
-		pool: CpuPool,
+		health: NodeHealth,
 		remote: Remote,
 		ui_address: Option<(String, u16)>,
 		extra_embed_on: Vec<(String, u16)>,
@ -236,11 +223,9 @@ impl Middleware {

 		let special = {
 			let mut special = special_endpoints(
-				ntp_servers,
-				pool,
+				health,
 				content_fetcher.clone(),
 				remote.clone(),
-				sync_status,
 			);
 			special.insert(
 				router::SpecialEndpoint::Home,
@ -270,20 +255,17 @@ impl http::RequestMiddleware for Middleware {
 	}
 }

-fn special_endpoints<T: AsRef<str>>(
-	ntp_servers: &[T],
-	pool: CpuPool,
+fn special_endpoints(
+	health: NodeHealth,
 	content_fetcher: Arc<apps::fetcher::Fetcher>,
 	remote: Remote,
-	sync_status: Arc<SyncStatus>,
 ) -> HashMap<router::SpecialEndpoint, Option<Box<endpoint::Endpoint>>> {
 	let mut special = HashMap::new();
 	special.insert(router::SpecialEndpoint::Rpc, None);
 	special.insert(router::SpecialEndpoint::Utils, Some(apps::utils()));
 	special.insert(router::SpecialEndpoint::Api, Some(api::RestApi::new(
 		content_fetcher,
-		sync_status,
-		api::TimeChecker::new(ntp_servers, pool),
+		health,
 		remote,
 	)));
 	special
--- a/dapps/src/tests/helpers/mod.rs
+++ b/dapps/src/tests/helpers/mod.rs
@ -26,7 +26,7 @@ use jsonrpc_http_server::{self as http, Host, DomainsValidation};
 use devtools::http_client;
 use hash_fetch::urlhint::ContractClient;
 use fetch::{Fetch, Client as FetchClient};
-use futures_cpupool::CpuPool;
+use node_health::{NodeHealth, TimeChecker, CpuPool};
 use parity_reactor::Remote;

 use {Middleware, SyncStatus, WebProxyTokens};
@ -39,6 +39,7 @@ use self::fetch::FakeFetch;

 const SIGNER_PORT: u16 = 18180;

+#[derive(Debug)]
 struct FakeSync(bool);
 impl SyncStatus for FakeSync {
 	fn is_major_importing(&self) -> bool { self.0 }
@ -254,9 +255,13 @@ impl Server {
 		remote: Remote,
 		fetch: F,
 	) -> Result<Server, http::Error> {
+		let health = NodeHealth::new(
+			sync_status.clone(),
+			TimeChecker::new::<String>(&[], CpuPool::new(1)),
+			remote.clone(),
+		);
 		let middleware = Middleware::dapps(
-			&["0.pool.ntp.org:123".into(), "1.pool.ntp.org:123".into()],
-			CpuPool::new(4),
+			health,
 			remote,
 			signer_address,
 			vec![],
--- a/js/src/api/rpc/parity/parity.js
+++ b/js/src/api/rpc/parity/parity.js
@ -385,6 +385,11 @@ export default class Parity {
      .then(outNumber);
  }

+  nodeHealth () {
+    return this._transport
+      .execute('parity_nodeHealth');
+  }
+
  nodeName () {
    return this._transport
      .execute('parity_nodeName');
--- a/js/src/redux/providers/status.js
+++ b/js/src/redux/providers/status.js
@ -200,7 +200,7 @@ export default class Status {
    const statusPromises = [
      this._api.eth.syncing(),
      this._api.parity.netPeers(),
-      this._fetchHealth()
+      this._api.parity.nodeHealth()
    ];

    return Promise
@ -247,13 +247,6 @@ export default class Status {
    };
  }

-  _fetchHealth = () => {
-    // Support Parity-Extension.
-    const uiUrl = this._api.transport.uiUrlWithProtocol || '';
-
-    return fetch(`${uiUrl}/api/health`).then(res => res.json());
-  }
-
  /**
   * The data fetched here should not change
   * unless Parity is restarted. They are thus
--- a/parity/configuration.rs
+++ b/parity/configuration.rs
@ -346,6 +346,7 @@ impl Configuration {
 				daemon: daemon,
 				logger_config: logger_config.clone(),
 				miner_options: self.miner_options(self.args.flag_reseal_min_period)?,
+				ntp_servers: self.ntp_servers(),
 				ws_conf: ws_conf,
 				http_conf: http_conf,
 				ipc_conf: ipc_conf,
@ -563,7 +564,6 @@ impl Configuration {
 	fn ui_config(&self) -> UiConfiguration {
 		UiConfiguration {
 			enabled: self.ui_enabled(),
-			ntp_servers: self.ntp_servers(),
 			interface: self.ui_interface(),
 			port: self.ui_port(),
 			hosts: self.ui_hosts(),
@ -576,7 +576,6 @@ impl Configuration {

 		DappsConfiguration {
 			enabled: self.dapps_enabled(),
-			ntp_servers: self.ntp_servers(),
 			dapps_path: PathBuf::from(self.directories().dapps),
 			extra_dapps: if self.args.cmd_dapp {
 				self.args.arg_path.iter().map(|path| PathBuf::from(path)).collect()
@ -1318,12 +1317,6 @@ mod tests {
 			support_token_api: true
 		}, UiConfiguration {
 			enabled: true,
-			ntp_servers: vec![
-				"0.parity.pool.ntp.org:123".into(),
-				"1.parity.pool.ntp.org:123".into(),
-				"2.parity.pool.ntp.org:123".into(),
-				"3.parity.pool.ntp.org:123".into(),
-			],
 			interface: "127.0.0.1".into(),
 			port: 8180,
 			hosts: Some(vec![]),
@ -1348,6 +1341,12 @@ mod tests {
 			daemon: None,
 			logger_config: Default::default(),
 			miner_options: Default::default(),
+			ntp_servers: vec![
+				"0.parity.pool.ntp.org:123".into(),
+				"1.parity.pool.ntp.org:123".into(),
+				"2.parity.pool.ntp.org:123".into(),
+				"3.parity.pool.ntp.org:123".into(),
+			],
 			ws_conf: Default::default(),
 			http_conf: Default::default(),
 			ipc_conf: Default::default(),
@ -1567,16 +1566,9 @@ mod tests {
 		let conf3 = parse(&["parity", "--ui-path", "signer", "--ui-interface", "test"]);

 		// then
-		let ntp_servers = vec![
-			"0.parity.pool.ntp.org:123".into(),
-			"1.parity.pool.ntp.org:123".into(),
-			"2.parity.pool.ntp.org:123".into(),
-			"3.parity.pool.ntp.org:123".into(),
-		];
 		assert_eq!(conf0.directories().signer, "signer".to_owned());
 		assert_eq!(conf0.ui_config(), UiConfiguration {
 			enabled: true,
-			ntp_servers: ntp_servers.clone(),
 			interface: "127.0.0.1".into(),
 			port: 8180,
 			hosts: Some(vec![]),
@ -1585,7 +1577,6 @@ mod tests {
 		assert_eq!(conf1.directories().signer, "signer".to_owned());
 		assert_eq!(conf1.ui_config(), UiConfiguration {
 			enabled: true,
-			ntp_servers: ntp_servers.clone(),
 			interface: "127.0.0.1".into(),
 			port: 8180,
 			hosts: Some(vec![]),
@ -1595,7 +1586,6 @@ mod tests {
 		assert_eq!(conf2.directories().signer, "signer".to_owned());
 		assert_eq!(conf2.ui_config(), UiConfiguration {
 			enabled: true,
-			ntp_servers: ntp_servers.clone(),
 			interface: "127.0.0.1".into(),
 			port: 3123,
 			hosts: Some(vec![]),
@ -1604,7 +1594,6 @@ mod tests {
 		assert_eq!(conf3.directories().signer, "signer".to_owned());
 		assert_eq!(conf3.ui_config(), UiConfiguration {
 			enabled: true,
-			ntp_servers: ntp_servers.clone(),
 			interface: "test".into(),
 			port: 8180,
 			hosts: Some(vec![]),
--- a/parity/dapps.rs
+++ b/parity/dapps.rs
@ -22,12 +22,12 @@ use ethcore::client::{Client, BlockChainClient, BlockId};
 use ethcore::transaction::{Transaction, Action};
 use ethsync::LightSync;
 use futures::{future, IntoFuture, Future, BoxFuture};
-use futures_cpupool::CpuPool;
 use hash_fetch::fetch::Client as FetchClient;
 use hash_fetch::urlhint::ContractClient;
 use helpers::replace_home;
 use light::client::Client as LightClient;
 use light::on_demand::{self, OnDemand};
+use node_health::{SyncStatus, NodeHealth};
 use rpc;
 use rpc_apis::SignerService;
 use parity_reactor;
@ -36,7 +36,6 @@ use util::{Bytes, Address};
 #[derive(Debug, PartialEq, Clone)]
 pub struct Configuration {
 	pub enabled: bool,
-	pub ntp_servers: Vec<String>,
 	pub dapps_path: PathBuf,
 	pub extra_dapps: Vec<PathBuf>,
 	pub extra_embed_on: Vec<(String, u16)>,
@ -48,12 +47,6 @@ impl Default for Configuration {
 		let data_dir = default_data_path();
 		Configuration {
 			enabled: true,
-			ntp_servers: vec![
-				"0.parity.pool.ntp.org:123".into(),
-				"1.parity.pool.ntp.org:123".into(),
-				"2.parity.pool.ntp.org:123".into(),
-				"3.parity.pool.ntp.org:123".into(),
-			],
 			dapps_path: replace_home(&data_dir, "$BASE/dapps").into(),
 			extra_dapps: vec![],
 			extra_embed_on: vec![],
@ -149,10 +142,10 @@ impl ContractClient for LightRegistrar {
 // to resolve.
 #[derive(Clone)]
 pub struct Dependencies {
+	pub node_health: NodeHealth,
 	pub sync_status: Arc<SyncStatus>,
 	pub contract_client: Arc<ContractClient>,
 	pub remote: parity_reactor::TokioRemote,
-	pub pool: CpuPool,
 	pub fetch: FetchClient,
 	pub signer: Arc<SignerService>,
 	pub ui_address: Option<(String, u16)>,
@ -165,7 +158,6 @@ pub fn new(configuration: Configuration, deps: Dependencies) -> Result<Option<Mi

 	server::dapps_middleware(
 		deps,
-		&configuration.ntp_servers,
 		configuration.dapps_path,
 		configuration.extra_dapps,
 		rpc::DAPPS_DOMAIN,
@ -174,19 +166,18 @@ pub fn new(configuration: Configuration, deps: Dependencies) -> Result<Option<Mi
 	).map(Some)
 }

-pub fn new_ui(enabled: bool, ntp_servers: &[String], deps: Dependencies) -> Result<Option<Middleware>, String> {
+pub fn new_ui(enabled: bool, deps: Dependencies) -> Result<Option<Middleware>, String> {
 	if !enabled {
 		return Ok(None);
 	}

 	server::ui_middleware(
 		deps,
-		ntp_servers,
 		rpc::DAPPS_DOMAIN,
 	).map(Some)
 }

-pub use self::server::{SyncStatus, Middleware, service};
+pub use self::server::{Middleware, service};

 #[cfg(not(feature = "dapps"))]
 mod server {
@ -196,11 +187,6 @@ mod server {
 	use parity_rpc::{hyper, RequestMiddleware, RequestMiddlewareAction};
 	use rpc_apis;

-	pub trait SyncStatus {
-		fn is_major_importing(&self) -> bool;
-		fn peers(&self) -> (usize, usize);
-	}
-
 	pub struct Middleware;
 	impl RequestMiddleware for Middleware {
 		fn on_request(
@ -212,7 +198,6 @@ mod server {

 	pub fn dapps_middleware(
 		_deps: Dependencies,
-		_ntp_servers: &[String],
 		_dapps_path: PathBuf,
 		_extra_dapps: Vec<PathBuf>,
 		_dapps_domain: &str,
@ -224,7 +209,6 @@ mod server {

 	pub fn ui_middleware(
 		_deps: Dependencies,
-		_ntp_servers: &[String],
 		_dapps_domain: &str,
 	) -> Result<Middleware, String> {
 		Err("Your Parity version has been compiled without UI support.".into())
@ -246,11 +230,9 @@ mod server {
 	use parity_reactor;

 	pub use parity_dapps::Middleware;
-	pub use parity_dapps::SyncStatus;

 	pub fn dapps_middleware(
 		deps: Dependencies,
-		ntp_servers: &[String],
 		dapps_path: PathBuf,
 		extra_dapps: Vec<PathBuf>,
 		dapps_domain: &str,
@ -262,8 +244,7 @@ mod server {
 		let web_proxy_tokens = Arc::new(move |token| signer.web_proxy_access_token_domain(&token));

 		Ok(parity_dapps::Middleware::dapps(
-			ntp_servers,
-			deps.pool,
+			deps.node_health,
 			parity_remote,
 			deps.ui_address,
 			extra_embed_on,
@ -280,13 +261,11 @@ mod server {

 	pub fn ui_middleware(
 		deps: Dependencies,
-		ntp_servers: &[String],
 		dapps_domain: &str,
 	) -> Result<Middleware, String> {
 		let parity_remote = parity_reactor::Remote::new(deps.remote.clone());
 		Ok(parity_dapps::Middleware::ui(
-			ntp_servers,
-			deps.pool,
+			deps.node_health,
 			parity_remote,
 			dapps_domain,
 			deps.contract_client,
--- a/parity/main.rs
+++ b/parity/main.rs
@ -58,6 +58,7 @@ extern crate ethcore_util as util;
 extern crate ethcore_network as network;
 extern crate ethkey;
 extern crate ethsync;
+extern crate node_health;
 extern crate panic_hook;
 extern crate parity_hash_fetch as hash_fetch;
 extern crate parity_ipfs_api;
--- a/parity/rpc.rs
+++ b/parity/rpc.rs
@ -73,7 +73,6 @@ impl Default for HttpConfiguration {
 #[derive(Debug, PartialEq, Clone)]
 pub struct UiConfiguration {
 	pub enabled: bool,
-	pub ntp_servers: Vec<String>,
 	pub interface: String,
 	pub port: u16,
 	pub hosts: Option<Vec<String>>,
@ -107,12 +106,6 @@ impl Default for UiConfiguration {
 	fn default() -> Self {
 		UiConfiguration {
 			enabled: true && cfg!(feature = "ui-enabled"),
-			ntp_servers: vec![
-				"0.parity.pool.ntp.org:123".into(),
-				"1.parity.pool.ntp.org:123".into(),
-				"2.parity.pool.ntp.org:123".into(),
-				"3.parity.pool.ntp.org:123".into(),
-			],
 			port: 8180,
 			interface: "127.0.0.1".into(),
 			hosts: Some(vec![]),
--- a/parity/rpc_apis.rs
+++ b/parity/rpc_apis.rs
@ -27,17 +27,18 @@ use ethcore::account_provider::AccountProvider;
 use ethcore::client::Client;
 use ethcore::miner::{Miner, ExternalMiner};
 use ethcore::snapshot::SnapshotService;
-use parity_rpc::{Metadata, NetworkSettings};
-use parity_rpc::informant::{ActivityNotifier, ClientNotifier};
-use parity_rpc::dispatch::{FullDispatcher, LightDispatcher};
+use ethcore_logger::RotatingLogger;
 use ethsync::{ManageNetwork, SyncProvider, LightSync};
 use hash_fetch::fetch::Client as FetchClient;
 use jsonrpc_core::{self as core, MetaIoHandler};
 use light::{TransactionQueue as LightTransactionQueue, Cache as LightDataCache};
+use node_health::NodeHealth;
+use parity_reactor;
+use parity_rpc::dispatch::{FullDispatcher, LightDispatcher};
+use parity_rpc::informant::{ActivityNotifier, ClientNotifier};
+use parity_rpc::{Metadata, NetworkSettings};
 use updater::Updater;
 use util::{Mutex, RwLock};
-use ethcore_logger::RotatingLogger;
-use parity_reactor;

 #[derive(Debug, PartialEq, Clone, Eq, Hash)]
 pub enum Api {
@ -217,6 +218,7 @@ pub struct FullDependencies {
 	pub settings: Arc<NetworkSettings>,
 	pub net_service: Arc<ManageNetwork>,
 	pub updater: Arc<Updater>,
+	pub health: NodeHealth,
 	pub geth_compatibility: bool,
 	pub dapps_service: Option<Arc<DappsService>>,
 	pub dapps_address: Option<(String, u16)>,
@ -300,12 +302,13 @@ impl FullDependencies {
 						false => None,
 					};
 					handler.extend_with(ParityClient::new(
-						&self.client,
-						&self.miner,
-						&self.sync,
-						&self.updater,
-						&self.net_service,
-						&self.secret_store,
+						self.client.clone(),
+						self.miner.clone(),
+						self.sync.clone(),
+						self.updater.clone(),
+						self.net_service.clone(),
+						self.health.clone(),
+						self.secret_store.clone(),
 						self.logger.clone(),
 						self.settings.clone(),
 						signer,
@ -403,6 +406,7 @@ pub struct LightDependencies {
 	pub secret_store: Arc<AccountProvider>,
 	pub logger: Arc<RotatingLogger>,
 	pub settings: Arc<NetworkSettings>,
+	pub health: NodeHealth,
 	pub on_demand: Arc<::light::on_demand::OnDemand>,
 	pub cache: Arc<Mutex<LightDataCache>>,
 	pub transaction_queue: Arc<RwLock<LightTransactionQueue>>,
@ -507,6 +511,7 @@ impl LightDependencies {
 						self.secret_store.clone(),
 						self.logger.clone(),
 						self.settings.clone(),
+						self.health.clone(),
 						signer,
 						self.dapps_address.clone(),
 						self.ws_address.clone(),
--- a/parity/run.rs
+++ b/parity/run.rs
@ -14,6 +14,7 @@
 // You should have received a copy of the GNU General Public License
 // along with Parity.  If not, see <http://www.gnu.org/licenses/>.

+use std::fmt;
 use std::sync::Arc;
 use std::net::{TcpListener};

@ -32,6 +33,7 @@ use fdlimit::raise_fd_limit;
 use hash_fetch::fetch::{Fetch, Client as FetchClient};
 use informant::{Informant, LightNodeInformantData, FullNodeInformantData};
 use light::Cache as LightDataCache;
+use node_health;
 use parity_reactor::EventLoop;
 use parity_rpc::{NetworkSettings, informant, is_major_importing};
 use updater::{UpdatePolicy, Updater};
@ -80,6 +82,7 @@ pub struct RunCmd {
 	pub daemon: Option<String>,
 	pub logger_config: LogConfig,
 	pub miner_options: MinerOptions,
+	pub ntp_servers: Vec<String>,
 	pub ws_conf: rpc::WsConfiguration,
 	pub http_conf: rpc::HttpConfiguration,
 	pub ipc_conf: rpc::IpcConfiguration,
@ -283,7 +286,7 @@ fn execute_light(cmd: RunCmd, can_restart: bool, logger: Arc<RotatingLogger>) ->

 	// the dapps server
 	let signer_service = Arc::new(signer::new_service(&cmd.ws_conf, &cmd.ui_conf, &cmd.logger_config));
-	let dapps_deps = {
+	let (node_health, dapps_deps) = {
 		let contract_client = Arc::new(::dapps::LightRegistrar {
 			client: service.client().clone(),
 			sync: light_sync.clone(),
@ -291,7 +294,12 @@ fn execute_light(cmd: RunCmd, can_restart: bool, logger: Arc<RotatingLogger>) ->
 		});

 		struct LightSyncStatus(Arc<LightSync>);
-		impl dapps::SyncStatus for LightSyncStatus {
+		impl fmt::Debug for LightSyncStatus {
+			fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+				write!(fmt, "Light Sync Status")
+			}
+		}
+		impl node_health::SyncStatus for LightSyncStatus {
 			fn is_major_importing(&self) -> bool { self.0.is_major_importing() }
 			fn peers(&self) -> (usize, usize) {
 				let peers = ethsync::LightSyncProvider::peer_numbers(&*self.0);
@ -299,19 +307,26 @@ fn execute_light(cmd: RunCmd, can_restart: bool, logger: Arc<RotatingLogger>) ->
 			}
 		}

-		dapps::Dependencies {
-			sync_status: Arc::new(LightSyncStatus(light_sync.clone())),
-			pool: fetch.pool(),
+		let sync_status = Arc::new(LightSyncStatus(light_sync.clone()));
+		let node_health = node_health::NodeHealth::new(
+			sync_status.clone(),
+			node_health::TimeChecker::new(&cmd.ntp_servers, fetch.pool()),
+			event_loop.remote(),
+		);
+
+		(node_health.clone(), dapps::Dependencies {
+			sync_status,
+			node_health,
 			contract_client: contract_client,
 			remote: event_loop.raw_remote(),
 			fetch: fetch.clone(),
 			signer: signer_service.clone(),
 			ui_address: cmd.ui_conf.address(),
-		}
+		})
 	};

 	let dapps_middleware = dapps::new(cmd.dapps_conf.clone(), dapps_deps.clone())?;
-	let ui_middleware = dapps::new_ui(cmd.ui_conf.enabled, &cmd.ui_conf.ntp_servers, dapps_deps)?;
+	let ui_middleware = dapps::new_ui(cmd.ui_conf.enabled, dapps_deps)?;

 	// start RPCs
 	let dapps_service = dapps::service(&dapps_middleware);
@ -320,6 +335,7 @@ fn execute_light(cmd: RunCmd, can_restart: bool, logger: Arc<RotatingLogger>) ->
 		client: service.client().clone(),
 		sync: light_sync.clone(),
 		net: light_sync.clone(),
+		health: node_health,
 		secret_store: account_provider,
 		logger: logger,
 		settings: Arc::new(cmd.net_settings),
@ -661,12 +677,17 @@ pub fn execute(cmd: RunCmd, can_restart: bool, logger: Arc<RotatingLogger>) -> R
 	let signer_service = Arc::new(signer::new_service(&cmd.ws_conf, &cmd.ui_conf, &cmd.logger_config));

 	// the dapps server
-	let dapps_deps = {
+	let (node_health, dapps_deps) = {
 		let (sync, client) = (sync_provider.clone(), client.clone());
 		let contract_client = Arc::new(::dapps::FullRegistrar { client: client.clone() });

 		struct SyncStatus(Arc<ethsync::SyncProvider>, Arc<Client>, ethsync::NetworkConfiguration);
-		impl dapps::SyncStatus for SyncStatus {
+		impl fmt::Debug for SyncStatus {
+			fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+				write!(fmt, "Dapps Sync Status")
+			}
+		}
+		impl node_health::SyncStatus for SyncStatus {
 			fn is_major_importing(&self) -> bool {
 				is_major_importing(Some(self.0.status().state), self.1.queue_info())
 			}
@ -676,18 +697,24 @@ pub fn execute(cmd: RunCmd, can_restart: bool, logger: Arc<RotatingLogger>) -> R
 			}
 		}

-		dapps::Dependencies {
-			sync_status: Arc::new(SyncStatus(sync, client, net_conf)),
-			pool: fetch.pool(),
+		let sync_status = Arc::new(SyncStatus(sync, client, net_conf));
+		let node_health = node_health::NodeHealth::new(
+			sync_status.clone(),
+			node_health::TimeChecker::new(&cmd.ntp_servers, fetch.pool()),
+			event_loop.remote(),
+		);
+		(node_health.clone(), dapps::Dependencies {
+			sync_status,
+			node_health,
 			contract_client: contract_client,
 			remote: event_loop.raw_remote(),
 			fetch: fetch.clone(),
 			signer: signer_service.clone(),
 			ui_address: cmd.ui_conf.address(),
-		}
+		})
 	};
 	let dapps_middleware = dapps::new(cmd.dapps_conf.clone(), dapps_deps.clone())?;
-	let ui_middleware = dapps::new_ui(cmd.ui_conf.enabled, &cmd.ui_conf.ntp_servers, dapps_deps)?;
+	let ui_middleware = dapps::new_ui(cmd.ui_conf.enabled, dapps_deps)?;

 	let dapps_service = dapps::service(&dapps_middleware);
 	let deps_for_rpc_apis = Arc::new(rpc_apis::FullDependencies {
@ -695,6 +722,7 @@ pub fn execute(cmd: RunCmd, can_restart: bool, logger: Arc<RotatingLogger>) -> R
 		snapshot: snapshot_service.clone(),
 		client: client.clone(),
 		sync: sync_provider.clone(),
+		health: node_health,
 		net: manage_network.clone(),
 		secret_store: secret_store,
 		miner: miner.clone(),
--- a/rpc/Cargo.toml
+++ b/rpc/Cargo.toml
@ -47,12 +47,13 @@ ethjson = { path = "../json" }
 ethcore-devtools = { path = "../devtools" }
 ethcore-light = { path = "../ethcore/light" }
 ethcore-logger = { path = "../logger" }
-vm = { path = "../ethcore/vm" }
-parity-updater = { path = "../updater" }
-parity-reactor = { path = "../util/reactor" }
-rlp = { path = "../util/rlp" }
 fetch = { path = "../util/fetch" }
+node-health = { path = "../dapps/node-health" }
+parity-reactor = { path = "../util/reactor" }
+parity-updater = { path = "../updater" }
+rlp = { path = "../util/rlp" }
 stats = { path = "../util/stats" }
+vm = { path = "../ethcore/vm" }

 clippy = { version = "0.0.103", optional = true}
 pretty_assertions = "0.1"
--- a/rpc/src/lib.rs
+++ b/rpc/src/lib.rs
@ -55,6 +55,7 @@ extern crate ethsync;
 extern crate ethcore_logger;
 extern crate vm;
 extern crate fetch;
+extern crate node_health;
 extern crate parity_reactor;
 extern crate parity_updater as updater;
 extern crate rlp;
--- a/rpc/src/v1/helpers/dispatch.rs
+++ b/rpc/src/v1/helpers/dispatch.rs
@ -584,8 +584,9 @@ fn decrypt(accounts: &AccountProvider, address: Address, msg: Bytes, password: S
 }

 /// Extract the default gas price from a client and miner.
-pub fn default_gas_price<C, M>(client: &C, miner: &M) -> U256
-	where C: MiningBlockChainClient, M: MinerService
+pub fn default_gas_price<C, M>(client: &C, miner: &M) -> U256 where
+	C: MiningBlockChainClient,
+	M: MinerService,
 {
 	client.gas_price_corpus(100).median().cloned().unwrap_or_else(|| miner.sensible_gas_price())
 }
--- a/rpc/src/v1/helpers/fake_sign.rs
+++ b/rpc/src/v1/helpers/fake_sign.rs
@ -24,8 +24,8 @@ use jsonrpc_core::Error;
 use v1::helpers::CallRequest;
 use v1::helpers::dispatch::default_gas_price;

-pub fn sign_call<B: MiningBlockChainClient, M: MinerService>(
-	client: &Arc<B>,
+pub fn sign_call<C: MiningBlockChainClient, M: MinerService> (
+	client: &Arc<C>,
 	miner: &Arc<M>,
 	request: CallRequest,
 	gas_cap: bool,
--- a/rpc/src/v1/impls/light/parity.rs
+++ b/rpc/src/v1/impls/light/parity.rs
@ -19,15 +19,15 @@ use std::sync::Arc;
 use std::collections::{BTreeMap, HashSet};
 use futures::{future, Future, BoxFuture};

-use ethcore_logger::RotatingLogger;
 use util::misc::version_data;

-use crypto::ecies;
+use crypto::{ecies, DEFAULT_MAC};
 use ethkey::{Brain, Generator};
 use ethstore::random_phrase;
 use ethsync::LightSyncProvider;
 use ethcore::account_provider::AccountProvider;
-use crypto::DEFAULT_MAC;
+use ethcore_logger::RotatingLogger;
+use node_health::{NodeHealth, Health};

 use light::client::LightChainClient;

@ -53,6 +53,7 @@ pub struct ParityClient {
 	accounts: Arc<AccountProvider>,
 	logger: Arc<RotatingLogger>,
 	settings: Arc<NetworkSettings>,
+	health: NodeHealth,
 	signer: Option<Arc<SignerService>>,
 	dapps_address: Option<(String, u16)>,
 	ws_address: Option<(String, u16)>,
@ -67,18 +68,20 @@ impl ParityClient {
 		accounts: Arc<AccountProvider>,
 		logger: Arc<RotatingLogger>,
 		settings: Arc<NetworkSettings>,
+		health: NodeHealth,
 		signer: Option<Arc<SignerService>>,
 		dapps_address: Option<(String, u16)>,
 		ws_address: Option<(String, u16)>,
 	) -> Self {
 		ParityClient {
-			light_dispatch: light_dispatch,
-			accounts: accounts,
-			logger: logger,
-			settings: settings,
-			signer: signer,
-			dapps_address: dapps_address,
-			ws_address: ws_address,
+			light_dispatch,
+			accounts,
+			logger,
+			settings,
+			health,
+			signer,
+			dapps_address,
+			ws_address,
 			eip86_transition: client.eip86_transition(),
 		}
 	}
@ -393,4 +396,10 @@ impl Parity for ParityClient {
 	fn call(&self, _meta: Self::Metadata, _requests: Vec<CallRequest>, _block: Trailing<BlockNumber>) -> BoxFuture<Vec<Bytes>, Error> {
 		future::err(errors::light_unimplemented(None)).boxed()
 	}
+
+	fn node_health(&self) -> BoxFuture<Health, Error> {
+		self.health.health()
+			.map_err(|err| errors::internal("Health API failure.", err))
+			.boxed()
+	}
 }
--- a/rpc/src/v1/impls/parity.rs
+++ b/rpc/src/v1/impls/parity.rs
@ -20,11 +20,10 @@ use std::str::FromStr;
 use std::collections::{BTreeMap, HashSet};
 use futures::{future, Future, BoxFuture};

-use ethcore_logger::RotatingLogger;
 use util::Address;
 use util::misc::version_data;

-use crypto::ecies;
+use crypto::{DEFAULT_MAC, ecies};
 use ethkey::{Brain, Generator};
 use ethstore::random_phrase;
 use ethsync::{SyncProvider, ManageNetwork};
@ -34,8 +33,9 @@ use ethcore::ids::BlockId;
 use ethcore::miner::MinerService;
 use ethcore::mode::Mode;
 use ethcore::transaction::SignedTransaction;
+use ethcore_logger::RotatingLogger;
+use node_health::{NodeHealth, Health};
 use updater::{Service as UpdateService};
-use crypto::DEFAULT_MAC;

 use jsonrpc_core::Error;
 use jsonrpc_macros::Trailing;
@ -53,17 +53,13 @@ use v1::types::{
 };

 /// Parity implementation.
-pub struct ParityClient<C, M, S: ?Sized, U> where
-	C: MiningBlockChainClient,
-	M: MinerService,
-	S: SyncProvider,
-	U: UpdateService,
-{
+pub struct ParityClient<C, M, U>  {
 	client: Arc<C>,
 	miner: Arc<M>,
-	sync: Arc<S>,
 	updater: Arc<U>,
+	sync: Arc<SyncProvider>,
 	net: Arc<ManageNetwork>,
+	health: NodeHealth,
 	accounts: Option<Arc<AccountProvider>>,
 	logger: Arc<RotatingLogger>,
 	settings: Arc<NetworkSettings>,
@ -73,39 +69,39 @@ pub struct ParityClient<C, M, S: ?Sized, U> where
 	eip86_transition: u64,
 }

-impl<C, M, S: ?Sized, U> ParityClient<C, M, S, U> where
+impl<C, M, U> ParityClient<C, M, U> where
 	C: MiningBlockChainClient,
-	M: MinerService,
-	S: SyncProvider,
-	U: UpdateService,
 {
 	/// Creates new `ParityClient`.
 	pub fn new(
-		client: &Arc<C>,
-		miner: &Arc<M>,
-		sync: &Arc<S>,
-		updater: &Arc<U>,
-		net: &Arc<ManageNetwork>,
-		store: &Option<Arc<AccountProvider>>,
+		client: Arc<C>,
+		miner: Arc<M>,
+		sync: Arc<SyncProvider>,
+		updater: Arc<U>,
+		net: Arc<ManageNetwork>,
+		health: NodeHealth,
+		accounts: Option<Arc<AccountProvider>>,
 		logger: Arc<RotatingLogger>,
 		settings: Arc<NetworkSettings>,
 		signer: Option<Arc<SignerService>>,
 		dapps_address: Option<(String, u16)>,
 		ws_address: Option<(String, u16)>,
 	) -> Self {
+		let eip86_transition = client.eip86_transition();
 		ParityClient {
-			client: client.clone(),
-			miner: miner.clone(),
-			sync: sync.clone(),
-			updater: updater.clone(),
-			net: net.clone(),
-			accounts: store.clone(),
-			logger: logger,
-			settings: settings,
-			signer: signer,
-			dapps_address: dapps_address,
-			ws_address: ws_address,
-			eip86_transition: client.eip86_transition(),
+			client,
+			miner,
+			sync,
+			updater,
+			net,
+			health,
+			accounts,
+			logger,
+			settings,
+			signer,
+			dapps_address,
+			ws_address,
+			eip86_transition,
 		}
 	}

@ -116,10 +112,9 @@ impl<C, M, S: ?Sized, U> ParityClient<C, M, S, U> where
 	}
 }

-impl<C, M, S: ?Sized, U> Parity for ParityClient<C, M, S, U> where
-	M: MinerService + 'static,
+impl<C, M, U> Parity for ParityClient<C, M, U> where
 	C: MiningBlockChainClient + 'static,
-	S: SyncProvider + 'static,
+	M: MinerService + 'static,
 	U: UpdateService + 'static,
 {
 	type Metadata = Metadata;
@ -429,4 +424,10 @@ impl<C, M, S: ?Sized, U> Parity for ParityClient<C, M, S, U> where

 		future::done(result).boxed()
 	}
+
+	fn node_health(&self) -> BoxFuture<Health, Error> {
+		self.health.health()
+			.map_err(|err| errors::internal("Health API failure.", err))
+			.boxed()
+	}
 }
--- a/rpc/src/v1/tests/mocked/parity.rs
+++ b/rpc/src/v1/tests/mocked/parity.rs
@ -15,13 +15,15 @@
 // along with Parity.  If not, see <http://www.gnu.org/licenses/>.

 use std::sync::Arc;
-use ethcore_logger::RotatingLogger;
-use util::{Address, U256};
-use ethsync::ManageNetwork;
 use ethcore::account_provider::AccountProvider;
 use ethcore::client::{TestBlockChainClient, Executed};
 use ethcore::miner::LocalTransactionStatus;
+use ethcore_logger::RotatingLogger;
 use ethstore::ethkey::{Generator, Random};
+use ethsync::ManageNetwork;
+use node_health::{self, NodeHealth};
+use parity_reactor;
+use util::Address;

 use jsonrpc_core::IoHandler;
 use v1::{Parity, ParityClient};
@ -30,13 +32,14 @@ use v1::helpers::{SignerService, NetworkSettings};
 use v1::tests::helpers::{TestSyncProvider, Config, TestMinerService, TestUpdater};
 use super::manage_network::TestManageNetwork;

-pub type TestParityClient = ParityClient<TestBlockChainClient, TestMinerService, TestSyncProvider, TestUpdater>;
+pub type TestParityClient = ParityClient<TestBlockChainClient, TestMinerService, TestUpdater>;

 pub struct Dependencies {
 	pub miner: Arc<TestMinerService>,
 	pub client: Arc<TestBlockChainClient>,
 	pub sync: Arc<TestSyncProvider>,
 	pub updater: Arc<TestUpdater>,
+	pub health: NodeHealth,
 	pub logger: Arc<RotatingLogger>,
 	pub settings: Arc<NetworkSettings>,
 	pub network: Arc<ManageNetwork>,
@ -54,6 +57,11 @@ impl Dependencies {
 				network_id: 3,
 				num_peers: 120,
 			})),
+			health: NodeHealth::new(
+				Arc::new(FakeSync),
+				node_health::TimeChecker::new::<String>(&[], node_health::CpuPool::new(1)),
+				parity_reactor::Remote::new_sync(),
+			),
 			updater: Arc::new(TestUpdater::default()),
 			logger: Arc::new(RotatingLogger::new("rpc=trace".to_owned())),
 			settings: Arc::new(NetworkSettings {
@ -75,12 +83,13 @@ impl Dependencies {
 		let opt_accounts = Some(self.accounts.clone());

 		ParityClient::new(
-			&self.client,
-			&self.miner,
-			&self.sync,
-			&self.updater,
-			&self.network,
-			&opt_accounts,
+			self.client.clone(),
+			self.miner.clone(),
+			self.sync.clone(),
+			self.updater.clone(),
+			self.network.clone(),
+			self.health.clone(),
+			opt_accounts.clone(),
 			self.logger.clone(),
 			self.settings.clone(),
 			signer,
@ -102,6 +111,13 @@ impl Dependencies {
 	}
 }

+#[derive(Debug)]
+struct FakeSync;
+impl node_health::SyncStatus for FakeSync {
+	fn is_major_importing(&self) -> bool { false }
+	fn peers(&self) -> (usize, usize) { (4, 25) }
+}
+
 #[test]
 fn rpc_parity_accounts_info() {
 	let deps = Dependencies::new();
@ -507,6 +523,8 @@ fn rpc_parity_cid() {

 #[test]
 fn rpc_parity_call() {
+	use util::U256;
+
 	let deps = Dependencies::new();
 	deps.client.set_execution_result(Ok(Executed {
 		exception: None,
@ -541,3 +559,14 @@ fn rpc_parity_call() {

 	assert_eq!(io.handle_request_sync(request), Some(response.to_owned()));
 }
+
+#[test]
+fn rpc_parity_node_health() {
+	let deps = Dependencies::new();
+	let io = deps.default_client();
+
+	let request = r#"{"jsonrpc": "2.0", "method": "parity_nodeHealth", "params":[], "id": 1}"#;
+	let response = r#"{"jsonrpc":"2.0","result":{"peers":{"details":[4,25],"message":"","status":"ok"},"sync":{"details":false,"message":"","status":"ok"},"time":{"details":0,"message":"","status":"ok"}},"id":1}"#;
+
+	assert_eq!(io.handle_request_sync(request), Some(response.to_owned()));
+}
--- a/rpc/src/v1/traits/parity.rs
+++ b/rpc/src/v1/traits/parity.rs
@ -22,6 +22,7 @@ use jsonrpc_core::Error;
 use jsonrpc_macros::Trailing;
 use futures::BoxFuture;

+use node_health::Health;
 use v1::types::{
 	H160, H256, H512, U256, Bytes, CallRequest,
 	Peers, Transaction, RpcSettings, Histogram,
@ -207,5 +208,9 @@ build_rpc_trait! {
 		/// Call contract, returning the output data.
 		#[rpc(meta, name = "parity_call")]
 		fn call(&self, Self::Metadata, Vec<CallRequest>, Trailing<BlockNumber>) -> BoxFuture<Vec<Bytes>, Error>;
+
+		/// Returns node's health report.
+		#[rpc(async, name = "parity_nodeHealth")]
+		fn node_health(&self) -> BoxFuture<Health, Error>;
 	}
 }
--- a/util/reactor/src/lib.rs
+++ b/util/reactor/src/lib.rs
@ -20,7 +20,7 @@
 extern crate futures;
 extern crate tokio_core;

-use std::thread;
+use std::{fmt, thread};
 use std::sync::mpsc;
 use std::time::Duration;
 use futures::{Future, IntoFuture};
@ -81,7 +81,19 @@ enum Mode {
 	ThreadPerFuture,
 }

-#[derive(Clone)]
+impl fmt::Debug for Mode {
+	fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+		use self::Mode::*;
+
+		match *self {
+			Tokio(_) => write!(fmt, "tokio"),
+			Sync => write!(fmt, "synchronous"),
+			ThreadPerFuture => write!(fmt, "thread per future"),
+		}
+	}
+}
+
+#[derive(Debug, Clone)]
 pub struct Remote {
 	inner: Mode,
 }