Add --chain option. (#122)

* Add --chain option.

* Reinstate bail on unknown runtime.

substrate/polkadot/cli/src/cli.yml

@@ -48,4 +48,9 @@ args:
       help: Specify a list of bootnodes
       takes_value: true
       multiple: true
+  - chain:
+      long: chain
+      value_name: CHAIN_SPEC
+      help: Specify the chain specification (one of dev or poc-1)
+      takes_value: true
 subcommands:

substrate/polkadot/cli/src/lib.rs

@@ -52,6 +52,7 @@ use std::net::SocketAddr;
 use futures::sync::mpsc;
 use futures::{Sink, Future, Stream};
 use tokio_core::reactor;
+use service::ChainSpec;
 
 /// Parse command line arguments and start the node.
 ///
@@ -104,6 +105,17 @@ pub fn run<I, T>(args: I) -> error::Result<()> where
 		role = service::Role::VALIDATOR;
 	}
 
+	match matches.value_of("chain") {
+		Some("poc-1") => config.chain_spec = ChainSpec::PoC1Testnet,
+		Some("dev") => config.chain_spec = ChainSpec::Development,
+		None => (),
+		Some(unknown) => panic!("Invalid chain name: {}", unknown),
+	}
+	info!("Chain specification: {}", match config.chain_spec {
+		ChainSpec::Development => "Local Development",
+		ChainSpec::PoC1Testnet => "PoC-1 Testnet",
+	});
+
 	config.roles = role;
 	config.network.boot_nodes = matches
 		.values_of("bootnodes")