add system-path output option

pkgs/oizys/oizys-go/cmd/output.go

@@ -14,6 +14,8 @@ var outputCmd = &cobra.Command{
 	},
 }
 
+
 func init() {
 	rootCmd.AddCommand(outputCmd)
+  outputCmd.Flags().BoolVar(&systemPath, "system-path", false, "show system-path drv")
 }

pkgs/oizys/oizys-go/cmd/root.go

@@ -32,6 +32,7 @@ var (
 	cacheName  string
 	verbose    bool
 	nom        bool
+	systemPath bool
 )
 
 var oizys = o.NewOizys()
@@ -40,7 +41,7 @@ var rootCmd = &cobra.Command{
 	Use:   "oizys",
 	Short: "nix begat oizys",
 	PersistentPreRun: func(cmd *cobra.Command, args []string) {
-    oizys.Set(flake, host, cacheName, verbose)
+		oizys.Set(flake, host, cacheName, verbose, systemPath)
 		oizys.CheckFlake()
 	},
 }

pkgs/oizys/oizys-go/internal/oizys/main.go

@@ -23,6 +23,7 @@ type Oizys struct {
 	host       string
 	cache      string
 	verbose    bool
+	systemPath bool
 }
 
 func NewOizys() *Oizys {
@@ -42,7 +43,44 @@ func NewOizys() *Oizys {
 	return &Oizys{flake: flake, host: hostname, cache: "daylin"}
 }
 
-func (o *Oizys) Output() string {
+type Derivation struct {
+	InputDrvs map[string]interface{}
+}
+
+func parseSystemPath(derivation map[string]Derivation) (string, error) {
+	for _, nixosDrv := range derivation {
+		for drv := range nixosDrv.InputDrvs {
+			if strings.HasSuffix(drv, "system-path.drv") {
+				return drv, nil
+			}
+		}
+	}
+	return "", errors.New("failed to find path for system-path.drv")
+}
+
+// recreating this command
+// nix derivation show `oizys output` | jq -r '.[].inputDrvs | with_entries(select(.key|match("system-path";"i"))) | keys | .[]'
+func (o *Oizys) getSystemPath() string {
+	cmd := exec.Command("nix", "derivation", "show", o.nixosConfigAttr())
+	log.Println("evaluating to get system-path")
+	cmd.Stderr = os.Stderr
+	out, err := cmd.Output()
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	var derivation map[string]Derivation
+	if err := json.Unmarshal(out, &derivation); err != nil {
+		log.Fatal(err)
+	}
+	systemPath, err := parseSystemPath(derivation)
+	if err != nil {
+		log.Fatal(err)
+	}
+	return systemPath
+}
+
+func (o *Oizys) nixosConfigAttr() string {
 	return fmt.Sprintf(
 		"%s#nixosConfigurations.%s.config.system.build.toplevel",
 		o.flake,
@@ -50,9 +88,17 @@ func (o *Oizys) Output() string {
 	)
 }
 
+func (o *Oizys) Output() string {
+	if o.systemPath {
+		return o.getSystemPath()
+	} else {
+		return o.nixosConfigAttr()
+	}
+}
+
 func (o *Oizys) Set(
 	flake, host, cache string,
-	verbose bool,
+	verbose, systemPath bool,
 ) {
 	if host != "" {
 		o.host = host
@@ -64,6 +110,7 @@ func (o *Oizys) Set(
 		o.cache = cache
 	}
 	o.verbose = verbose
+	o.systemPath = systemPath
 }
 
 func terminalSize() (int, int) {
@@ -153,7 +200,11 @@ func (o *Oizys) git(rest ...string) *exec.Cmd {
 }
 
 func showFailedOutput(buf []byte) {
-	arrow := lipgloss.NewStyle().Bold(true).Foreground(lipgloss.Color("9")).Render("->")
+	arrow := lipgloss.
+		NewStyle().
+		Bold(true).
+		Foreground(lipgloss.Color("9")).
+		Render("->")
 	for _, line := range strings.Split(strings.TrimSpace(string(buf)), "\n") {
 		fmt.Println(arrow, line)
 	}
@@ -208,7 +259,7 @@ func showDryRunResult(nixOutput string, verbose bool) {
 
 func (o *Oizys) NixDryRun(verbose bool, rest ...string) {
 	args := []string{
-		"build", o.Output(), "--dry-run",
+		"build", o.nixosConfigAttr(), "--dry-run",
 	}
 	args = append(args, rest...)
 	cmd := exec.Command("nix", args...)
@@ -302,7 +353,7 @@ func (o *Oizys) Checks(nom bool, rest ...string) {
 func (o *Oizys) CacheBuild(rest ...string) {
 	args := []string{
 		"watch-exec", o.cache, "--", "nix",
-		"build", o.Output(), "--print-build-logs",
+		"build", o.nixosConfigAttr(), "--print-build-logs",
 		"--accept-flake-config",
 	}
 	args = append(args, rest...)
@@ -325,14 +376,6 @@ func (o *Oizys) CI(rest ...string) {
 	runCommand(cmd)
 }
 
-func Output(flake string, host string) string {
-	return fmt.Sprintf(
-		"%s#nixosConfigurations.%s.config.system.build.toplevel",
-		flake,
-		host,
-	)
-}
-
 func nixSpinner(host string) *spinner.Spinner {
 	msg := fmt.Sprintf("%s %s", " evaluating derivation for:",
 		lipgloss.NewStyle().Bold(true).Foreground(lipgloss.Color("6")).Render(host),