feat: ledger replay with 'fake' validator keypair

tools/genx/README.md

@@ -14,5 +14,51 @@ if they exist on chain
 ```sh
 cargo run --release --bin genx test-validator \
   --rpc-port 7799 --url 'https://rpc.magicblock.app/mainnet' \
-  test-integration/ledgers/ledgers
+ ledger
 ```
+
+Then you run the script to start a mainnet standin locally.
+
+Also make sure to update the config with which to start the ephemeral validator that will
+replay the ledger to point to the port that it is running on.
+
+#### Config Example
+
+```toml
+[accounts]
+remote = ["http://127.0.0.1:7799", "ws://127.0.0.1:7800"]
+lifecycle = "ephemeral"
+commit = { frequency_millis = 50_000 }
+payer = { init_sol = 1_000 }
+
+[rpc]
+addr = "0.0.0.0"
+port = 8899
+
+[validator]
+millis_per_slot = 50
+
+[ledger]
+reset = false
+path = "./ledger"
+```
+
+### test-ledger
+
+Prepares a ledger for replay in a diagnostics/test scenario. At this point it ensures that the
+original keypair of the validator operator is not used. Instead it is overwritten with a random
+keypair. That keypair is then printed to the terminal so that the `VALIDATOR_KEYPAIR` env var
+can be set to it when running the ephemeral validator to replay the ledger.
+
+One can auto-set that env var using the output of this command as follows:
+
+```sh
+export VALIDATOR_KEYPAIR=$(cargo run --bin genx -- test-ledger ./ledger)
+```
+
+Then we can just do the following to replay the ledger (i.e. providing the above config):
+
+```sh
+cargo run --release ledger-config.toml
+```
+

tools/genx/src/ledger_replay_test.rs

@@ -0,0 +1,46 @@
+use std::fs;
+use std::path::PathBuf;
+
+use solana_sdk::signature::Keypair;
+use solana_sdk::signer::{EncodableKey, Signer};
+
+pub(crate) fn ledger_replay_test(ledger_path: &PathBuf) {
+    match fs::exists(ledger_path) {
+        Ok(x) if !x => {
+            panic!("Ledger path does not exist: {}", ledger_path.display())
+        }
+        Err(err) => {
+            panic!(
+                "Error looking up ledger path: {} ({})",
+                ledger_path.display(),
+                err
+            )
+        }
+        _ => {}
+    }
+
+    let keypair_file = ledger_path.join("validator-keypair.json");
+
+    if let Ok(true) = fs::exists(&keypair_file) {
+        if let Ok(kp) = Keypair::read_from_file(&keypair_file) {
+            eprintln!("Overwriting existing keypair: {}", kp.pubkey());
+        }
+    }
+
+    let kp = Keypair::new();
+    Keypair::write_to_file(&kp, &keypair_file)
+        .expect("Failed to write keypair");
+
+    eprintln!(
+        "Wrote test validator authority (pubkey: {}) to ledger",
+        kp.pubkey()
+    );
+    let base58 = kp.to_base58_string();
+    eprintln!(
+        "Add the keypair to your environment via 'export VALIDATOR_KEYPAIR={}'\n",
+        base58
+    );
+
+    // Print the base58 keypair to stdout for easy copy/paste and output capture
+    println!("{}", base58);
+}

tools/genx/src/main.rs

@@ -2,6 +2,7 @@ use std::path::PathBuf;
 
 use clap::{Parser, Subcommand};
 use test_validator::TestValidatorConfig;
+mod ledger_replay_test;
 mod test_validator;
 
 #[derive(Debug, Parser)]
@@ -29,6 +30,13 @@ enum Commands {
         #[arg(long)]
         url: String,
     },
+    /// Prepares the ledger for testing
+    #[command(name = "test-ledger")]
+    #[command(
+        about = "Prepares the ledger for testing",
+        long_about = "(Over)writes the validator keypair"
+    )]
+    LedgerReplayTest { ledger_path: PathBuf },
 }
 
 fn main() {
@@ -45,5 +53,8 @@ fn main() {
                 config,
             )
         }
+        Commands::LedgerReplayTest { ledger_path } => {
+            ledger_replay_test::ledger_replay_test(&ledger_path)
+        }
     }
 }