Created Function to Reduce Duplicated Code

common/clap_utils/Cargo.toml

@@ -13,3 +13,7 @@ dirs = "3.0.1"
 eth2_network_config = { path = "../eth2_network_config" }
 eth2_ssz = "0.4.1"
 ethereum-types = "0.12.1"
+serde = "1.0.116"
+serde_json = "1.0.59"
+serde_yaml = "0.8.13"
+types = { path = "../../consensus/types"}

common/clap_utils/src/lib.rs

@@ -6,6 +6,7 @@ use ethereum_types::U256 as Uint256;
 use ssz::Decode;
 use std::path::PathBuf;
 use std::str::FromStr;
+use types::{ChainSpec, Config, EthSpec};
 
 pub mod flags;
 
@@ -163,3 +164,29 @@ pub fn parse_ssz_optional<T: Decode>(
         })
         .transpose()
 }
+
+/// Writes configs to file if `dump-config` or `dump-chain-config` flags are set
+pub fn check_dump_configs<S, E>(
+    matches: &ArgMatches,
+    config: S,
+    spec: &ChainSpec,
+) -> Result<(), String>
+where
+    S: serde::Serialize,
+    E: EthSpec,
+{
+    if let Some(dump_path) = parse_optional::<PathBuf>(matches, "dump-config")? {
+        let mut file = std::fs::File::create(dump_path)
+            .map_err(|e| format!("Failed to open file for writing config: {:?}", e))?;
+        serde_json::to_writer(&mut file, &config)
+            .map_err(|e| format!("Error serializing config: {:?}", e))?;
+    }
+    if let Some(dump_path) = parse_optional::<PathBuf>(matches, "dump-chain-config")? {
+        let chain_config = Config::from_chain_spec::<E>(spec);
+        let mut file = std::fs::File::create(dump_path)
+            .map_err(|e| format!("Failed to open file for writing chain config: {:?}", e))?;
+        serde_yaml::to_writer(&mut file, &chain_config)
+            .map_err(|e| format!("Error serializing config: {:?}", e))?;
+    }
+    Ok(())
+}