Make --file optional for generate-node-key (#7043)

This pr makes the `--file` argument optional to `generate-node-key`.
If the argument is not given, the secret node key will be printed to
`stdout`. The public node key will always be printed to `stderr`.

bin/utils/subkey/src/lib.rs

@@ -31,7 +31,8 @@ use sp_core::crypto::Ss58Codec;
  about = "Utility for generating and restoring with Substrate keys",
 )]
 pub enum Subkey {
- /// Generate a random node libp2p key, save it to file and print its peer ID
+ /// Generate a random node libp2p key, save it to file or print it to stdout
+ /// and print its peer ID to stderr.
  GenerateNodeKey(GenerateNodeKeyCmd),
 
  /// Generate a random account

client/cli/src/commands/generate_node_key.rs

@@ -26,26 +26,31 @@ use libp2p::identity::{ed25519 as libp2p_ed25519, PublicKey};
 #[derive(Debug, StructOpt)]
 #[structopt(
  name = "generate-node-key",
- about = "Generate a random node libp2p key, save it to file and print its peer ID"
+ about = "Generate a random node libp2p key, save it to \
+ file or print it to stdout and print its peer ID to stderr"
 )]
 pub struct GenerateNodeKeyCmd {
  /// Name of file to save secret key to.
+ ///
+ /// If not given, the secret key is printed to stdout.
  #[structopt(long)]
- file: PathBuf,
+ file: Option<PathBuf>,
 }
 
 impl GenerateNodeKeyCmd {
  /// Run the command
  pub fn run(&self) -> Result<(), Error> {
- let file = &self.file;
-
  let keypair = libp2p_ed25519::Keypair::generate();
  let secret = keypair.secret();
  let peer_id = PublicKey::Ed25519(keypair.public()).into_peer_id();
+ let secret_hex = hex::encode(secret.as_ref());
 
- fs::write(file, hex::encode(secret.as_ref()))?;
+ match &self.file {
+ Some(file) => fs::write(file, secret_hex)?,
+ None => print!("{}", secret_hex),
+ }
 
- println!("{}", peer_id);
+ eprintln!("{}", peer_id);
 
  Ok(())
  }

client/cli/src/commands/key.rs

@@ -28,10 +28,11 @@ use super::{
  generate_node_key::GenerateNodeKeyCmd,
 };
 
-/// key utilities for the cli.
+/// Key utilities for the cli.
 #[derive(Debug, StructOpt)]
 pub enum KeySubcommand {
- /// Generate a random node libp2p key, save it to file and print its peer ID
+ /// Generate a random node libp2p key, save it to file or print it to stdout
+ /// and print its peer ID to stderr.
  GenerateNodeKey(GenerateNodeKeyCmd),
 
  /// Generate a random account