add --build-host flag for remote builds

Author: alyraffauf

src/lib.go

@@ -20,10 +20,18 @@ type JobSpec struct {
 	User     string `json:"user"`     // ssh user
 }
 
-func buildClosure(flake string, spec JobSpec) (string, error) {
+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)
 
-	data, err := runJSON("nix", "build", "--no-link", "--json", expr)
+	var data []byte
+	var err error
+
+	if builder != "localhost" {
+		data, err = runJSON("nix", "build", "--no-link", "--json", "--store", fmt.Sprintf("ssh-ng://%s", builder), expr)
+	} else {
+		data, err = runJSON("nix", "build", "--no-link", "--json", expr)
+	}
+
 	if err != nil {
 		return "", fmt.Errorf("Failed to build %s: %v", spec.Output, err)
 	}
@@ -36,6 +44,10 @@ func buildClosure(flake string, spec JobSpec) (string, error) {
 	out, ok := res[0].Outputs["out"]
 	if !ok {
 		return "", fmt.Errorf("Missing 'out' for %s", spec.Output)
+	} else if builder != "localhost" {
+		if _, err := run("nix", "copy", "--from", "ssh-ng://"+builder, out, "--no-check-sigs"); err != nil {
+			return "", fmt.Errorf("Error copying from %s: %v", builder, err)
+		}
 	}
 
 	return out, nil
@@ -59,7 +71,7 @@ func deployClosure(name string, spec JobSpec, outs map[string]string, op string)
 		cmds = append(cmds, []string{"ssh", target, "sudo", path + "/bin/switch-to-configuration", op})
 	}
 
-	if _, err := run("nix", "copy", "--to", "ssh://"+target, path); err != nil {
+	if _, err := run("nix", "copy", "--to", "ssh-ng://"+target, path); err != nil {
 		return fmt.Errorf("error copying to %s: %v", target, err)
 	}
 

src/main.go

@@ -32,19 +32,21 @@ func main() {
 		cfgDefault = "deployments.nix"
 	}
 
-	flakeFlag := flag.String("flake", flakeDefault, "Flake URL or path.")
-	opFlag := flag.String("operation", opDefault, "Operation to perform.")
+	buildHostFlag := flag.String("build-host", "localhost", "Build closures on a specified remote host instead of locally.")
 	cfgFlag := flag.String("deployments", cfgDefault, "Path to deployments file.")
+	flakeFlag := flag.String("flake", flakeDefault, "Flake URL or path.")
 	jobsFlag := flag.String("jobs", "", "Filtered, comma-separated subset of deployment jobs to run.")
+	opFlag := flag.String("operation", opDefault, "Operation to perform.")
 	skipFlag := flag.String("skip", "", "Comma-separated list of deployment jobs to skip.")
 	verboseFlag := flag.Bool("verbose", false, "Enable verbose output.")
 
 	flag.Parse()
 
-	flake := *flakeFlag
-	op := *opFlag
+	buildHost := *buildHostFlag
 	cfg := *cfgFlag
+	flake := *flakeFlag
 	jobFilter := *jobsFlag
+	op := *opFlag
 	skipFilter := *skipFlag
 	verbose := *verboseFlag
 
@@ -114,7 +116,8 @@ func main() {
 	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)
+
+		out, err := buildClosure(flake, spec, buildHost)
 		if err != nil {
 			fatal("Failure building closures: %v", err)
 		}