RPC: expose chain spec properties (#1104)

* Add properties to chain spec

* Read properties as serde_json::Value

* Use a serde json::map::Map directly for properties

* Add type alias for json Map

* Update chain_spec.rs

substrate/Cargo.lock

@@ -3325,6 +3325,7 @@ dependencies = [
  "parity-codec 2.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "parking_lot 0.4.8 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc-hex 2.0.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde_json 1.0.32 (registry+https://github.com/rust-lang/crates.io-index)",
  "sr-primitives 0.1.0",
  "sr-version 0.1.0",
  "substrate-client 0.1.0",

substrate/core/rpc/Cargo.toml

@@ -11,6 +11,7 @@ jsonrpc-pubsub = { git="https://github.com/paritytech/jsonrpc.git" }
 log = "0.4"
 parking_lot = "0.4"
 parity-codec = "2.1"
+serde_json = "1.0"
 substrate-client = { path = "../client" }
 substrate-executor = { path = "../executor" }
 substrate-transaction-pool = { path = "../transaction-pool" }

substrate/core/rpc/src/system/mod.rs

@@ -37,5 +37,9 @@ build_rpc_trait! {
 		/// Get the chain's type. Given as a string identifier.
 		#[rpc(name = "system_chain")]
 		fn system_chain(&self) -> Result<String>;
+
+		/// Get a custom set of properties as a JSON object, defined in the chain spec.
+		#[rpc(name = "system_properties")]
+		fn system_properties(&self) -> Result<serde_json::map::Map<String, serde_json::Value>>;
 	}
 }

substrate/core/rpc/src/system/tests.rs

@@ -27,6 +27,9 @@ impl SystemApi for () {
 	fn system_chain(&self) -> Result<String> {
 		Ok("testchain".into())
 	}
+	fn system_properties(&self) -> Result<serde_json::map::Map<String, serde_json::Value>> {
+		Ok(serde_json::map::Map::new())
+	}
 }
 
 #[test]
@@ -52,3 +55,11 @@ fn system_chain_works() {
 		"testchain".to_owned()
 	);
 }
+
+#[test]
+fn system_properties_works() {
+	assert_eq!(
+		SystemApi::system_properties(&()).unwrap(),
+		serde_json::map::Map::new()
+	);
+}

substrate/core/service/src/chain_spec.rs

@@ -88,8 +88,12 @@ struct ChainSpecFile {
 	pub telemetry_url: Option<String>,
 	pub protocol_id: Option<String>,
 	pub consensus_engine: Option<String>,
+	pub properties: Option<Properties>,
 }
 
+/// Arbitrary properties defined in chain spec as a JSON object
+pub type Properties = json::map::Map<String, json::Value>;
+
 /// A configuration of a chain. Can be used to build a genesis block.
 pub struct ChainSpec<G: RuntimeGenesis> {
 	spec: ChainSpecFile,
@@ -130,6 +134,11 @@ impl<G: RuntimeGenesis> ChainSpec<G> {
 		self.spec.consensus_engine.as_ref().map(String::as_str)
 	}
 
+	pub fn properties(&self) -> Properties {
+		// Return an empty JSON object if 'properties' not defined in config
+		self.spec.properties.as_ref().unwrap_or(&json::map::Map::new()).clone()
+	}
+
 	/// Parse json content into a `ChainSpec`
 	pub fn from_embedded(json: &'static [u8]) -> Result<Self, String> {
 		let spec = json::from_slice(json).map_err(|e| format!("Error parsing spec file: {}", e))?;
@@ -158,6 +167,7 @@ impl<G: RuntimeGenesis> ChainSpec<G> {
 		telemetry_url: Option<&str>,
 		protocol_id: Option<&str>,
 		consensus_engine: Option<&str>,
+		properties: Option<Properties>,
 	) -> Self
 	{
 		let spec = ChainSpecFile {
@@ -167,6 +177,7 @@ impl<G: RuntimeGenesis> ChainSpec<G> {
 			telemetry_url: telemetry_url.map(str::to_owned),
 			protocol_id: protocol_id.map(str::to_owned),
 			consensus_engine: consensus_engine.map(str::to_owned),
+			properties,
 		};
 		ChainSpec {
 			spec,

substrate/core/service/src/lib.rs

@@ -78,7 +78,7 @@ use codec::{Encode, Decode};
 
 pub use self::error::{ErrorKind, Error};
 pub use config::{Configuration, Roles, PruningMode};
-pub use chain_spec::ChainSpec;
+pub use chain_spec::{ChainSpec, Properties};
 pub use transaction_pool::txpool::{self, Pool as TransactionPool, Options as TransactionPoolOptions, ChainApi, IntoPoolError};
 pub use client::ExecutionStrategy;
 
@@ -235,6 +235,7 @@ impl<Components> Service<Components>
 		// RPC
 		let rpc_config = RpcConfig {
 			chain_name: config.chain_spec.name().to_string(),
+			properties: config.chain_spec.properties().clone(),
 			impl_name: config.impl_name,
 			impl_version: config.impl_version,
 		};
@@ -378,6 +379,7 @@ fn maybe_start_server<T, F>(address: Option<SocketAddr>, start: F) -> Result<Opt
 #[derive(Clone)]
 struct RpcConfig {
 	chain_name: String,
+	properties: Properties,
 	impl_name: &'static str,
 	impl_version: &'static str,
 }
@@ -394,6 +396,10 @@ impl substrate_rpc::system::SystemApi for RpcConfig {
 	fn system_chain(&self) -> substrate_rpc::system::error::Result<String> {
 		Ok(self.chain_name.clone())
 	}
+
+	fn system_properties(&self) -> substrate_rpc::system::error::Result<Properties> {
+		Ok(self.properties.clone())
+	}
 }
 
 /// Transaction pool adapter.

substrate/node/cli/res/bbq-birch.json

@@ -1,6 +1,9 @@
 {
 	"name": "BBQ Birch",
 	"id": "bbq-birch",
+	"properties": {
+		"tokenSymbol": "BBQ"
+	},
 	"telemetryUrl": "wss://telemetry.polkadot.io/submit/",
 	"protocolId": null,
 	"bootNodes": [

substrate/node/cli/src/chain_spec.rs

@@ -140,6 +140,7 @@ pub fn staging_testnet_config() -> ChainSpec {
 		Some(STAGING_TELEMETRY_URL.into()),
 		None,
 		None,
+		None,
 	)
 }
 
@@ -240,7 +241,7 @@ fn development_config_genesis() -> GenesisConfig {
 
 /// Development config (single validator Alice)
 pub fn development_config() -> ChainSpec {
-	ChainSpec::from_genesis("Development", "development", development_config_genesis, vec![], None, None, None)
+	ChainSpec::from_genesis("Development", "development", development_config_genesis, vec![], None, None, None, None)
 }
 
 fn local_testnet_genesis() -> GenesisConfig {
@@ -254,7 +255,7 @@ fn local_testnet_genesis() -> GenesisConfig {
 
 /// Local testnet config (multivalidator Alice + Bob)
 pub fn local_testnet_config() -> ChainSpec {
-	ChainSpec::from_genesis("Local Testnet", "local_testnet", local_testnet_genesis, vec![], None, None, None)
+	ChainSpec::from_genesis("Local Testnet", "local_testnet", local_testnet_genesis, vec![], None, None, None, None)
 }
 
 #[cfg(test)]
@@ -271,7 +272,7 @@ mod tests {
 
 	/// Local testnet config (multivalidator Alice + Bob)
 	pub fn integration_test_config() -> ChainSpec {
-		ChainSpec::from_genesis("Integration Test", "test", local_testnet_genesis_instant, vec![], None, None, None)
+		ChainSpec::from_genesis("Integration Test", "test", local_testnet_genesis_instant, vec![], None, None, None, None)
 	}
 
 	#[test]