Added a CLI command to update the parameters for the layout computation (for now, only the zone redundancy)

src/garage/cli/layout.rs

@@ -14,8 +14,8 @@ pub async fn cli_layout_command_dispatch(
 	rpc_host: NodeID,
 ) -> Result<(), Error> {
 	match cmd {
-		LayoutOperation::Assign(configure_opt) => {
+		LayoutOperation::Assign(assign_opt) => {
-			cmd_assign_role(system_rpc_endpoint, rpc_host, configure_opt).await
+			cmd_assign_role(system_rpc_endpoint, rpc_host, assign_opt).await
 		}
 		LayoutOperation::Remove(remove_opt) => {
 			cmd_remove_role(system_rpc_endpoint, rpc_host, remove_opt).await
@@ -27,6 +27,9 @@ pub async fn cli_layout_command_dispatch(
 		LayoutOperation::Revert(revert_opt) => {
 			cmd_revert_layout(system_rpc_endpoint, rpc_host, revert_opt).await
 		}
+        LayoutOperation::Config(config_opt) => {
+            cmd_config_layout(system_rpc_endpoint, rpc_host, config_opt).await
+        }
 	}
 }
 
@@ -245,6 +248,34 @@ pub async fn cmd_revert_layout(
 	Ok(())
 }
 
+pub async fn cmd_config_layout(
+	rpc_cli: &Endpoint<SystemRpc, ()>,
+	rpc_host: NodeID,
+	config_opt: ConfigLayoutOpt,
+) -> Result<(), Error> {
+	let mut layout = fetch_layout(rpc_cli, rpc_host).await?;
+    
+    match config_opt.redundancy {
+        None => (),
+        Some(r) => {
+            if r > layout.replication_factor {
+                println!("The zone redundancy must be smaller or equal to the \
+                replication factor ({}).", layout.replication_factor);
+            }
+            else if r < 1 {
+                println!("The zone redundancy must be at least 1.");
+            }
+            else {
+                layout.parameters.update(LayoutParameters{ zone_redundancy: r });
+                println!("The new zone redundancy has been staged.");
+            }
+        }
+    }
+
+	send_layout(rpc_cli, rpc_host, layout).await?;
+    Ok(())
+}
+
 // --- utility ---
 
 pub async fn fetch_layout(

src/garage/cli/structs.rs

@@ -86,6 +86,10 @@ pub enum LayoutOperation {
 	/// Remove role from Garage cluster node
 	#[structopt(name = "remove", version = garage_version())]
 	Remove(RemoveRoleOpt),
+    
+    /// Configure parameters value for the layout computation
+	#[structopt(name = "config", version = garage_version())]
+    Config(ConfigLayoutOpt),
 
 	/// Show roles currently assigned to nodes and changes staged for commit
 	#[structopt(name = "show", version = garage_version())]
@@ -100,6 +104,7 @@ pub enum LayoutOperation {
 	Revert(RevertLayoutOpt),
 }
 
+
 #[derive(StructOpt, Debug)]
 pub struct AssignRoleOpt {
 	/// Node(s) to which to assign role (prefix of hexadecimal node id)
@@ -110,7 +115,7 @@ pub struct AssignRoleOpt {
 	#[structopt(short = "z", long = "zone")]
 	pub(crate) zone: Option<String>,
 
-	/// Capacity (in relative terms, use 1 to represent your smallest server)
+	/// Capacity (in relative terms)
 	#[structopt(short = "c", long = "capacity")]
 	pub(crate) capacity: Option<u32>,
 
@@ -133,6 +138,13 @@ pub struct RemoveRoleOpt {
 	pub(crate) node_id: String,
 }
 
+#[derive(StructOpt, Debug)]
+pub struct ConfigLayoutOpt {
+	/// Zone redundancy parameter
+	#[structopt(short = "r", long = "redundancy")]
+	pub(crate) redundancy: Option<usize>,
+}
+
 #[derive(StructOpt, Debug)]
 pub struct ApplyLayoutOpt {
 	/// Version number of new configuration: this command will fail if