Fix issues with testnet dir and update docs (#992)

lighthouse/environment/src/lib.rs

@@ -7,8 +7,7 @@
 //! `Context` which can be handed to any service that wishes to start async tasks or perform
 //! logging.
 
-use clap::ArgMatches;
-use eth2_config::{read_from_file, Eth2Config};
+use eth2_config::Eth2Config;
 use eth2_testnet_config::Eth2TestnetConfig;
 use futures::{sync::oneshot, Future};
 use slog::{info, o, Drain, Level, Logger};
@@ -139,72 +138,26 @@ impl<E: EthSpec> EnvironmentBuilder<E> {
     }
 
     /// Setups eth2 config using the CLI arguments.
-    pub fn setup_eth2_config(
+    pub fn eth2_testnet_config(
         mut self,
-        datadir: PathBuf,
-        eth2_testnet_config: Eth2TestnetConfig<E>,
-        cli_args: &ArgMatches,
+        eth2_testnet_config: &Eth2TestnetConfig<E>,
     ) -> Result<Self, String> {
-        self.load_eth2_config(&datadir)?;
-
-        match cli_args.subcommand() {
-            ("testnet", Some(sub_cli_args)) => {
-                // Modify the `SECONDS_PER_SLOT` "constant".
-                if let Some(slot_time) = sub_cli_args.value_of("slot-time") {
-                    let slot_time = slot_time
-                        .parse::<u64>()
-                        .map_err(|e| format!("Unable to parse slot-time: {:?}", e))?;
-
-                    self.eth2_config.spec.milliseconds_per_slot = slot_time;
-                }
-            }
-            _ => {
-                if !datadir.exists() {
-                    // Create a new chain spec from the default configuration.
-                    self.eth2_config.spec = eth2_testnet_config
-                        .yaml_config
-                        .as_ref()
-                        .ok_or_else(|| {
-                            "The testnet directory must contain a spec config".to_string()
-                        })?
-                        .apply_to_chain_spec::<E>(&self.eth2_config.spec)
-                        .ok_or_else(|| {
-                            format!(
-                                "The loaded config is not compatible with the {} spec",
-                                &self.eth2_config.spec_constants
-                            )
-                        })?;
-                }
-            }
-        }
+        // Create a new chain spec from the default configuration.
+        self.eth2_config.spec = eth2_testnet_config
+            .yaml_config
+            .as_ref()
+            .ok_or_else(|| "The testnet directory must contain a spec config".to_string())?
+            .apply_to_chain_spec::<E>(&self.eth2_config.spec)
+            .ok_or_else(|| {
+                format!(
+                    "The loaded config is not compatible with the {} spec",
+                    &self.eth2_config.spec_constants
+                )
+            })?;
 
         Ok(self)
     }
 
-    /// Loads the eth2 config if the file exists.
-    fn load_eth2_config(&mut self, datadir: &PathBuf) -> Result<(), String> {
-        let filename = datadir.join(ETH2_CONFIG_FILENAME);
-        if filename.exists() {
-            let loaded_eth2_config: Eth2Config = read_from_file(filename.clone())
-                .map_err(|e| format!("Unable to parse {:?} file: {:?}", filename, e))?
-                .ok_or_else(|| format!("{:?} file does not exist", filename))?;
-
-            // The loaded spec must be using the same spec constants (e.g., minimal, mainnet) as the
-            // client expects.
-            if loaded_eth2_config.spec_constants == self.eth2_config.spec_constants {
-                self.eth2_config = loaded_eth2_config;
-            } else {
-                return Err(format!(
-                    "Eth2 config loaded from disk does not match client spec version. Got {} \
-                         expected {}",
-                    &loaded_eth2_config.spec_constants, &self.eth2_config.spec_constants
-                ));
-            }
-        }
-
-        Ok(())
-    }
-
     /// Consumes the builder, returning an `Environment`.
     pub fn build(self) -> Result<Environment<E>, String> {
         Ok(Environment {

lighthouse/src/main.rs

@@ -1,7 +1,7 @@
 #[macro_use]
 extern crate clap;
 
-use beacon_node::{get_data_dir, get_eth2_testnet_config, get_testnet_dir, ProductionBeaconNode};
+use beacon_node::{get_eth2_testnet_config, get_testnet_dir, ProductionBeaconNode};
 use clap::{App, Arg, ArgMatches};
 use env_logger::{Builder, Env};
 use environment::EnvironmentBuilder;
@@ -73,6 +73,18 @@ fn main() {
                 .help("Data directory for lighthouse keys and databases.")
                 .takes_value(true),
         )
+        .arg(
+            Arg::with_name("testnet-dir")
+                .long("testnet-dir")
+                .value_name("DIR")
+                .help(
+                    "Path to directory containing eth2_testnet specs. Defaults to \
+                      a hard-coded Lighthouse testnet. Only effective if there is no \
+                      existing database.",
+                )
+                .takes_value(true)
+                .global(true),
+        )
         .subcommand(beacon_node::cli_app())
         .subcommand(validator_client::cli_app())
         .subcommand(account_manager::cli_app())
@@ -110,15 +122,12 @@ fn run<E: EthSpec>(
         .ok_or_else(|| "Expected --debug-level flag".to_string())?;
 
     let log_format = matches.value_of("log-format");
+    let eth2_testnet_config = get_eth2_testnet_config(&get_testnet_dir(matches))?;
 
     let mut environment = environment_builder
         .async_logger(debug_level, log_format)?
         .multi_threaded_tokio_runtime()?
-        .setup_eth2_config(
-            get_data_dir(matches),
-            get_eth2_testnet_config(&get_testnet_dir(matches))?,
-            matches,
-        )?
+        .eth2_testnet_config(&eth2_testnet_config)?
         .build()?;
 
     let log = environment.core_context().log;