lib: create instantiateDRvPath to separate eval steps from build steps

Author: alyraffauf

src/lib.go

@@ -21,26 +21,11 @@ type JobSpec struct {
 	User     string `json:"user"`     // ssh user
 }
 
-func buildClosure(flake string, spec JobSpec, builder string) (string, error) {
-	expr := fmt.Sprintf("%s#%sConfigurations.%s.config.system.build.toplevel", flake, spec.Type, spec.Output)
-	drvExpr := expr + ".drvPath"
-
-	// Step 1: Evaluate the .drv path locally
-	data, err := runJSON("nix", "--extra-experimental-features", "nix-command flakes", "eval", "--raw", drvExpr)
-	if err != nil {
-		return "", fmt.Errorf("failed to evaluate drvPath for %s: %w", spec.Output, err)
-	}
-	drvPath := strings.TrimSpace(string(data))
-
-	// Step 2: Copy the .drv closure to the remote builder (if needed)
-	if builder != "localhost" {
-		if _, err := run("nix", "--extra-experimental-features", "nix-command flakes", "copy", "--to", "ssh-ng://"+builder, drvPath); err != nil {
-			return "", fmt.Errorf("failed to copy .drv to %s: %w", builder, err)
-		}
-	}
-
-	// Step 3: Build the closure from the drv remotely or locally
+func buildClosure(spec JobSpec, drvPath string, builder string) (string, error) {
 	var buildOut []byte
+	var err error
+
+	// Build the closure locally or on the remote builder
 	if builder != "localhost" {
 		buildOut, err = runJSON("nix", "--extra-experimental-features", "nix-command flakes", "build", "--no-link", "--json", "--store", "ssh-ng://"+builder, drvPath+"^*")
 	} else {
@@ -50,7 +35,7 @@ func buildClosure(flake string, spec JobSpec, builder string) (string, error) {
 		return "", fmt.Errorf("failed to build %s on %s: %w", spec.Output, builder, err)
 	}
 
-	// Step 4: Parse the output path
+	// Parse the output path
 	var results []BuildResult
 	if err := json.Unmarshal(buildOut, &results); err != nil {
 		return "", fmt.Errorf("invalid build JSON for %s: %w\nRaw: %s", spec.Output, err, string(buildOut))
@@ -113,6 +98,28 @@ func info(format string, args ...any) {
 	fmt.Printf("[nynx] "+format+"\n", args...)
 }
 
+func instantiateDrvPath(flake string, spec JobSpec, builder string) (string, error) {
+	expr := fmt.Sprintf("%s#%sConfigurations.%s.config.system.build.toplevel", flake, spec.Type, spec.Output)
+	drvExpr := expr + ".drvPath"
+
+	// Evaluate the .drv path locally
+	data, err := runJSON("nix", "--extra-experimental-features", "nix-command flakes", "eval", "--raw", drvExpr)
+	if err != nil {
+		return "", fmt.Errorf("failed to evaluate drvPath for %s: %w", spec.Output, err)
+	}
+
+	drvPath := strings.TrimSpace(string(data))
+
+	// Copy the .drv to the remote builder (if needed)
+	if builder != "localhost" {
+		if _, err := run("nix", "--extra-experimental-features", "nix-command flakes", "copy", "--to", "ssh-ng://"+builder, drvPath); err != nil {
+			return "", fmt.Errorf("failed to copy .drv to %s: %w", builder, err)
+		}
+	}
+
+	return drvPath, nil
+}
+
 func loadDeploymentSpec(cfg string) (map[string]JobSpec, error) {
 	// Nix -> JSON
 	data, err := runJSON("nix", "eval", "--json", "-f", cfg)

src/main.go

@@ -111,13 +111,28 @@ func main() {
 		verboseInfo(verbose, "✔ Operations validated.")
 	}
 
+	verboseInfo(verbose, "Instantiating drvPath(s) for %d job(s)...", len(jobs))
+
+	drvPaths := make(map[string]string, len(jobs))
+	for name, spec := range jobs {
+		verboseInfo(verbose, "Instantiating drvPath for %s#%s...", flake, spec.Output)
+
+		drv, err := instantiateDrvPath(flake, spec, buildHost)
+		if err != nil {
+			fatal("Failed to instantiate drvPath for job '%s': %v", name, err)
+		}
+		drvPaths[name] = drv
+
+		info("✔ Instantiated drvPath for %s#%s.", flake, spec.Output)
+	}
+
 	verboseInfo(verbose, "Building closures for %d job(s)...", len(jobs))
 
 	outs := make(map[string]string, len(jobs))
 	for name, spec := range jobs {
 		verboseInfo(verbose, "Building %s#%s...", flake, spec.Output)
 
-		out, err := buildClosure(flake, spec, buildHost)
+		out, err := buildClosure(spec, drvPaths[name], buildHost)
 		if err != nil {
 			fatal("Failure building closures: %v", err)
 		}