Add --staking flag (#1641)

## Issue Addressed

Closes #1472 

## Proposed Changes

Add `--staking` ~~and`staking-with-eth1-endpoint`~~ flag to improve UX for stakers.


Co-authored-by: Paul Hauner <paul@paulhauner.com>

beacon_node/client/src/builder.rs

@@ -599,8 +599,15 @@ where
             .ok_or_else(|| "caching_eth1_backend requires a chain spec".to_string())?;
 
         // Check if the eth1 endpoint we connect to is on the correct network id.
+        // Note: This check also effectively checks the eth1 http connection before the beacon chain
+        // is completely started and fails loudly if there is an issue.
         let network_id =
-            eth1::http::get_network_id(&config.endpoint, Duration::from_millis(15_000)).await?;
+            eth1::http::check_eth1_endpoint(&config.endpoint, Duration::from_millis(15_000))
+                .await
+                .map_err(|_| "Error connecting to eth1 node.\n\
+                    Please ensure that you have an eth1 http server running locally on localhost:8545 \
+                    or pass an external endpoint using `--eth1-endpoint <SERVER-ADDRESS>`.\n\
+                    Also ensure that `eth` and `net` apis are enabled on the eth1 http server.".to_string())?;
 
         if network_id != config.network_id {
             return Err(format!(

beacon_node/eth1/src/http.rs

@@ -55,6 +55,19 @@ impl FromStr for Eth1NetworkId {
     }
 }
 
+/// Checks that the provided eth1 node has all the relevant api endpoints open
+/// and returns the network id.
+pub async fn check_eth1_endpoint(
+    endpoint: &str,
+    timeout: Duration,
+) -> Result<Eth1NetworkId, String> {
+    // Checks that the "eth" api works as expected.
+    let _block_number = get_block_number(endpoint, timeout).await?;
+    // Checks that the "net" api works as expected.
+    let network_id = get_network_id(endpoint, timeout).await?;
+    Ok(network_id)
+}
+
 /// Get the eth1 network id of the given endpoint.
 pub async fn get_network_id(endpoint: &str, timeout: Duration) -> Result<Eth1NetworkId, String> {
     let response_body = send_rpc_request(endpoint, "net_version", json!([]), timeout).await?;

beacon_node/src/cli.rs

@@ -193,6 +193,19 @@ pub fn cli_app<'a, 'b>() -> App<'a, 'b> {
                 .takes_value(true),
         )
 
+        /*
+         * Standard staking flags
+         */
+
+        .arg(
+            Arg::with_name("staking")
+                .long("staking")
+                .help("Standard option for a staking beacon node. Equivalent to \
+                `lighthouse bn --http --eth1 `. This will enable the http server on localhost:5052 \
+                and try connecting to an eth1 node on localhost:8545")
+                .takes_value(false)
+        )
+
         /*
          * Eth1 Integration
          */

beacon_node/src/config.rs

@@ -4,7 +4,7 @@ use clap_utils::BAD_TESTNET_DIR_MESSAGE;
 use client::{config::DEFAULT_DATADIR, ClientConfig, ClientGenesis};
 use eth2_libp2p::{multiaddr::Protocol, Enr, Multiaddr, NetworkConfig, PeerIdSerialized};
 use eth2_testnet_config::Eth2TestnetConfig;
-use slog::{crit, info, Logger};
+use slog::{crit, info, warn, Logger};
 use ssz::Encode;
 use std::cmp;
 use std::fs;
@@ -83,6 +83,16 @@ pub fn get_config<E: EthSpec>(
         false,
     )?;
 
+    /*
+     * Staking flag
+     * Note: the config values set here can be overwritten by other more specific cli params
+     */
+
+    if cli_args.is_present("staking") {
+        client_config.rest_api.enabled = true;
+        client_config.sync_eth1_chain = true;
+    }
+
     /*
      * Http server
      */
@@ -112,6 +122,15 @@ pub fn get_config<E: EthSpec>(
         client_config.rest_api.allow_origin = allow_origin.to_string();
     }
 
+    // Log a warning indicating an open HTTP server if it wasn't specified explicitly
+    // (e.g. using the --staking flag).
+    if cli_args.is_present("staking") {
+        warn!(
+            log,
+            "Running HTTP server on port {}", client_config.rest_api.port
+        );
+    }
+
     /*
      * Websocket server
      */
@@ -426,7 +445,7 @@ pub fn set_network_config(
 
     if cli_args.is_present("disable-discovery") {
         config.disable_discovery = true;
-        slog::warn!(log, "Discovery is disabled. New peers will not be found");
+        warn!(log, "Discovery is disabled. New peers will not be found");
     }
 
     Ok(())

book/src/become-a-validator-source.md

@@ -47,7 +47,7 @@ the internet and maintains a view of the chain.
 Start your beacon node with:
 
 ```bash
- lighthouse --testnet medalla beacon --eth1 --http
+ lighthouse --testnet medalla beacon --staking
 ```
 
 > The `--testnet` parameter is optional. Omitting it will default to the
@@ -55,8 +55,11 @@ Start your beacon node with:
 > Current values are either `altona` or `medalla`. This is true for all the
 > following commands in this document.
 
->Note:  the `--http` flag enables the HTTP API for the validator client. And the `--eth1` flag tells the beacon node that it should sync with an Ethereum1 node (e.g. Geth). These flags are only required if you wish to run a validator.
+You can also pass an external http endpoint (e.g. Infura) for the Eth1 node using the `--eth1-endpoint` flag:
 
+```bash
+ lighthouse --testnet medalla beacon --staking --eth1-endpoint <ETH1-SERVER>
+```
 
 Your beacon node has started syncing when you see the following (truncated)
 log: