Adds --no-validator CLI flag (#3348)

* Implement `is_validator` for offchain-workers

* Introduce `--no-validator` flag

* Don't run babe/grandpa/im-online when `--no-validator` is given

* Fixes compilation

* Bump spec version

* Improve error handling in executor

* Add missing extern function

* Revert making error public

* Remove `--no-validator` CLI

substrate/core/service/src/components.rs

@@ -268,6 +268,7 @@ pub trait OffchainWorker<C: Components> {
 		>,
 		pool: &Arc<TransactionPool<C::TransactionPoolApi>>,
 		network_state: &Arc<dyn NetworkStateInfo + Send + Sync>,
+		is_validator: bool,
 	) -> error::Result<Box<dyn Future<Item = (), Error = ()> + Send>>;
 }
 
@@ -284,8 +285,9 @@ impl<C: Components> OffchainWorker<Self> for C where
 		>,
 		pool: &Arc<TransactionPool<C::TransactionPoolApi>>,
 		network_state: &Arc<dyn NetworkStateInfo + Send + Sync>,
+		is_validator: bool,
 	) -> error::Result<Box<dyn Future<Item = (), Error = ()> + Send>> {
-		let future = offchain.on_block_imported(number, pool, network_state.clone())
+		let future = offchain.on_block_imported(number, pool, network_state.clone(), is_validator)
 			.map(|()| Ok(()));
 		Ok(Box::new(Compat::new(future)))
 	}

substrate/core/service/src/lib.rs

@@ -153,7 +153,7 @@ impl<Components: components::Components> Service<Components> {
 	pub fn new(
 		mut config: FactoryFullConfiguration<Components::Factory>,
 	) -> Result<Self, error::Error> {
-		let (signal, exit) = ::exit_future::signal();
+		let (signal, exit) = exit_future::signal();
 
 		// List of asynchronous tasks to spawn. We collect them, then spawn them all at once.
 		let (to_spawn_tx, to_spawn_rx) =
@@ -250,6 +250,7 @@ impl<Components: components::Components> Service<Components> {
 			let offchain = offchain_workers.as_ref().map(Arc::downgrade);
 			let to_spawn_tx_ = to_spawn_tx.clone();
 			let network_state_info: Arc<dyn NetworkStateInfo + Send + Sync> = network.clone();
+			let is_validator = config.roles.is_authority();
 
 			let events = client.import_notification_stream()
 				.map(|v| Ok::<_, ()>(v)).compat()
@@ -270,6 +271,7 @@ impl<Components: components::Components> Service<Components> {
 							&offchain,
 							&txpool,
 							&network_state_info,
+							is_validator,
 						).map_err(|e| warn!("Offchain workers error processing new block: {:?}", e))?;
 						let _ = to_spawn_tx_.unbounded_send(future);
 					}