Add nasctl: Go NAS control plane with React frontend

internal/modules/nfs/exports.tmpl

@@ -0,0 +1,4 @@
+# Generated by nasctl. Do not edit manually.
+{{range .Exports}}
+{{.Path}} {{.ClientSpec}}
+{{- end}}

internal/modules/nfs/nfs.go

@@ -0,0 +1,168 @@
+package nfs
+
+import (
+	"bytes"
+	"context"
+	"embed"
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+	"text/template"
+
+	"github.com/darroyo/nasctl/internal/db"
+	"github.com/darroyo/nasctl/internal/system"
+)
+
+const ModuleName = "nfs"
+
+//go:embed exports.tmpl
+var exportsTemplate embed.FS
+
+type Config struct {
+	ExportsPath string
+	Reload      bool
+}
+
+type Module struct {
+	cfg Config
+}
+
+type templateExport struct {
+	Path       string
+	ClientSpec string
+}
+
+type templateData struct {
+	Exports []templateExport
+}
+
+func New(cfg Config) *Module {
+	if cfg.ExportsPath == "" {
+		cfg.ExportsPath = "/etc/exports"
+	}
+	return &Module{cfg: cfg}
+}
+
+func (m *Module) Name() string {
+	return ModuleName
+}
+
+func (m *Module) IsDirty(ctx context.Context, database *db.DB) (bool, error) {
+	return database.IsDirty(ModuleName)
+}
+
+func (m *Module) Apply(ctx context.Context, database *db.DB) error {
+	exports, err := database.ListNFSExports()
+	if err != nil {
+		return err
+	}
+
+	content, err := m.renderConfig(exports)
+	if err != nil {
+		return err
+	}
+
+	if err := writeAtomic(m.cfg.ExportsPath, content); err != nil {
+		return err
+	}
+
+	if m.cfg.Reload {
+		stdout, stderr, err := system.Run(ctx, "exportfs", "-ra")
+		if err != nil {
+			return fmt.Errorf("exportfs -ra: %w (stdout=%q stderr=%q)", err, stdout, stderr)
+		}
+	}
+
+	message := fmt.Sprintf("applied %d nfs export(s) to %s", len(exports), m.cfg.ExportsPath)
+	if err := database.AppendApplyLog(ModuleName, message, true); err != nil {
+		return err
+	}
+	return database.ClearDirty(ModuleName)
+}
+
+// clientSpec builds the "client(opts) client(opts)" segment of an exports line.
+// If no clients are configured, it defaults to "*(opts)".
+func clientSpec(clients []string, options string) string {
+	opts := strings.TrimSpace(options)
+	if opts == "" {
+		opts = "ro"
+	}
+	if len(clients) == 0 {
+		return fmt.Sprintf("*(%s)", opts)
+	}
+	specs := make([]string, 0, len(clients))
+	for _, client := range clients {
+		client = strings.TrimSpace(client)
+		if client == "" {
+			continue
+		}
+		specs = append(specs, fmt.Sprintf("%s(%s)", client, opts))
+	}
+	if len(specs) == 0 {
+		return fmt.Sprintf("*(%s)", opts)
+	}
+	return strings.Join(specs, " ")
+}
+
+func (m *Module) renderConfig(exports []db.NFSExport) ([]byte, error) {
+	tmplContent, err := exportsTemplate.ReadFile("exports.tmpl")
+	if err != nil {
+		return nil, fmt.Errorf("read exports template: %w", err)
+	}
+
+	tmpl, err := template.New("exports").Parse(string(tmplContent))
+	if err != nil {
+		return nil, fmt.Errorf("parse exports template: %w", err)
+	}
+
+	data := templateData{Exports: make([]templateExport, 0, len(exports))}
+	for _, export := range exports {
+		data.Exports = append(data.Exports, templateExport{
+			Path:       export.Path,
+			ClientSpec: clientSpec(export.Clients, export.Options),
+		})
+	}
+
+	var buf bytes.Buffer
+	if err := tmpl.Execute(&buf, data); err != nil {
+		return nil, fmt.Errorf("execute exports template: %w", err)
+	}
+	return buf.Bytes(), nil
+}
+
+func writeAtomic(path string, content []byte) error {
+	dir := filepath.Dir(path)
+	if err := os.MkdirAll(dir, 0o755); err != nil {
+		return fmt.Errorf("create config dir: %w", err)
+	}
+
+	tmp, err := os.CreateTemp(dir, ".exports.*")
+	if err != nil {
+		return fmt.Errorf("create temp file: %w", err)
+	}
+	tmpPath := tmp.Name()
+
+	cleanup := func() {
+		_ = tmp.Close()
+		_ = os.Remove(tmpPath)
+	}
+
+	if _, err := tmp.Write(content); err != nil {
+		cleanup()
+		return fmt.Errorf("write temp config: %w", err)
+	}
+	if err := tmp.Chmod(0o644); err != nil {
+		cleanup()
+		return fmt.Errorf("chmod temp config: %w", err)
+	}
+	if err := tmp.Close(); err != nil {
+		cleanup()
+		return fmt.Errorf("close temp config: %w", err)
+	}
+	if err := os.Rename(tmpPath, path); err != nil {
+		cleanup()
+		return fmt.Errorf("rename temp config: %w", err)
+	}
+	return nil
+}