apply_local: Don't bother evaluating other hosts

src/command/apply_local.rs

@@ -98,11 +98,8 @@ pub async fn run(_global_args: &ArgMatches<'_>, local_args: &ArgMatches<'_>) {
     };
     let goal = Goal::from_str(local_args.value_of("goal").unwrap()).unwrap();
 
-    log::info!("Enumerating nodes...");
-    let all_nodes = hive.deployment_info().await.unwrap();
-
     let target: Target = {
-        if let Some(info) = all_nodes.get(&hostname) {
+        if let Some(info) = hive.deployment_info_for(&hostname).await.unwrap() {
             if !info.allows_local_deployment() {
                 log::error!("Local deployment is not enabled for host {}.", hostname);
                 log::error!("Hint: Set deployment.allowLocalDeployment to true.");

src/nix/hive.rs

@@ -46,7 +46,7 @@ impl Hive {
         &self.hive
     }
 
-    /// Retrieve deployment info for all nodes
+    /// Retrieve deployment info for all nodes.
     pub async fn deployment_info(&self) -> NixResult<HashMap<String, NodeConfig>> {
         // FIXME: Really ugly :(
         let s: String = self.nix_instantiate("hive.deploymentConfigJson").eval()
@@ -62,6 +62,15 @@ impl Hive {
         Ok(configs)
     }
 
+    /// Retrieve deployment info for a single node.
+    pub async fn deployment_info_for(&self, node: &str) -> NixResult<Option<NodeConfig>> {
+        let expr = format!("toJSON (hive.nodes.\"{}\".config.deployment or null)", node);
+        let s: String = self.nix_instantiate(&expr).eval()
+            .capture_json().await?;
+
+        Ok(serde_json::from_str(&s).unwrap())
+    }
+
     /// Evaluates selected nodes.
     ///
     /// Evaluation may take up a lot of memory, so we make it possible