Add block-height subcommand

cli/src/cluster_query.rs

@@ -115,6 +115,10 @@ impl ClusterQuerySubCommands for App<'_, '_> {
             .alias("get-slot")
             .arg(commitment_arg()),
         )
+        .subcommand(
+            SubCommand::with_name("block-height").about("Get current block height")
+            .arg(commitment_arg()),
+        )
         .subcommand(
             SubCommand::with_name("epoch").about("Get current epoch")
             .arg(commitment_arg()),
@@ -362,6 +366,13 @@ pub fn parse_get_slot(_matches: &ArgMatches<'_>) -> Result<CliCommandInfo, CliEr
     })
 }
 
+pub fn parse_get_block_height(_matches: &ArgMatches<'_>) -> Result<CliCommandInfo, CliError> {
+    Ok(CliCommandInfo {
+        command: CliCommand::GetBlockHeight,
+        signers: vec![],
+    })
+}
+
 pub fn parse_largest_accounts(matches: &ArgMatches<'_>) -> Result<CliCommandInfo, CliError> {
     let filter = if matches.is_present("circulating") {
         Some(RpcLargestAccountsFilter::Circulating)
@@ -651,6 +662,13 @@ pub fn process_get_slot(rpc_client: &RpcClient, config: &CliConfig) -> ProcessRe
     Ok(slot.to_string())
 }
 
+pub fn process_get_block_height(rpc_client: &RpcClient, config: &CliConfig) -> ProcessResult {
+    let epoch_info: CliEpochInfo = rpc_client
+        .get_epoch_info_with_commitment(config.commitment)?
+        .into();
+    Ok(epoch_info.epoch_info.block_height.to_string())
+}
+
 pub fn parse_show_block_production(matches: &ArgMatches<'_>) -> Result<CliCommandInfo, CliError> {
     let epoch = value_t!(matches, "epoch", Epoch).ok();
     let slot_limit = value_t!(matches, "slot_limit", u64).ok();