Embed templates into binary (#2169)

* Embed config templates

* Embed export templates

* Embed graph templates

* Just call the export Template "export"

* Use path "__full" for builtin full export template

* fix embedded static files

* rewrite for switch

* align docs with the export template and graph changes

---------

Co-authored-by: Roman Dodin <[email protected]>

clab/config/template.go

@@ -2,7 +2,10 @@ package config
 
 import (
 	"context"
+	"embed"
 	"fmt"
+	"io/fs"
+	"os"
 	"path/filepath"
 	"strings"
 	"text/template"
@@ -51,20 +54,27 @@ func LoadTemplates(tmpl *template.Template, role string) error {
 	return nil
 }
 
+//go:embed templates
+var embeddedTemplates embed.FS
+
 func RenderAll(allnodes map[string]*NodeConfig) error {
 	if len(TemplatePaths) == 0 { // default is the install path
 		TemplatePaths = []string{"@"}
 	}
 
-	for i, v := range TemplatePaths {
+	var TemplateFS []fs.FS
+
+	for _, v := range TemplatePaths {
 		if v == "@" {
-			TemplatePaths[i] = "/etc/containerlab/templates/"
+			TemplateFS = append(TemplateFS, embeddedTemplates)
+		} else {
+			TemplateFS = append(TemplateFS, os.DirFS(v))
 		}
 	}
 
 	if len(TemplateNames) == 0 {
 		var err error
-		TemplateNames, err = GetTemplateNamesInDirs(TemplatePaths)
+		TemplateNames, err = GetTemplateNamesInDirs(TemplateFS)
 		if err != nil {
 			return err
 		}

clab/config/utils.go

@@ -2,8 +2,8 @@ package config
 
 import (
 	"fmt"
+	"io/fs"
 	"net/netip"
-	"path/filepath"
 	"reflect"
 	"strconv"
 	"strings"
@@ -274,15 +274,15 @@ func ipFarEnd(in netip.Prefix) netip.Prefix {
 // GetTemplateNamesInDirs returns a list of template file names found in a list of dir `paths`
 // without traversing nested dirs
 // template names are following the pattern <some-name>__<role/kind>.tmpl.
-func GetTemplateNamesInDirs(paths []string) ([]string, error) {
+func GetTemplateNamesInDirs(dirs []fs.FS) ([]string, error) {
 	var tnames []string
-	for _, p := range paths {
-		all, err := filepath.Glob(filepath.Join(p, "*__*.tmpl"))
+	for _, dir := range dirs {
+		all, err := fs.Glob(dir, "*__*.tmpl")
 		if err != nil {
 			return nil, err
 		}
 		for _, fn := range all {
-			tn := strings.Split(filepath.Base(fn), "__")[0]
+			tn := strings.Split(fn, "__")[0]
 			// skip adding templates with the same name
 			if len(tnames) > 0 && tnames[len(tnames)-1] == tn {
 				continue

clab/export.go

@@ -6,9 +6,9 @@ package clab
 
 import (
 	"context"
+	_ "embed"
 	"encoding/json"
 	"io"
-	"path/filepath"
 	"text/template"
 
 	"github.com/hairyhenderson/gomplate/v3"
@@ -41,10 +41,15 @@ type TopologyExport struct {
 	NodeConfigs map[string]*types.NodeConfig `json:"nodeconfigs,omitempty"`
 }
 
+//go:embed export_templates/auto.tmpl
+var defaultExportTemplate string
+
+//go:embed export_templates/full.tmpl
+var fullExportTemplate string
+
 // exportTopologyDataWithTemplate generates and writes topology data file to w using a template.
 func (c *CLab) exportTopologyDataWithTemplate(_ context.Context, w io.Writer, p string) error {
-	n := filepath.Base(p)
-	t, err := template.New(n).
+	t := template.New("export").
 		Funcs(gomplate.CreateFuncs(context.Background(), new(data.Data))).
 		Funcs(template.FuncMap{
 			"ToJSON": func(v interface{}) string {
@@ -55,8 +60,19 @@ func (c *CLab) exportTopologyDataWithTemplate(_ context.Context, w io.Writer, p
 				a, _ := json.MarshalIndent(v, prefix, indent)
 				return string(a)
 			},
-		}).
-		ParseFiles(p)
+		})
+
+	var err error
+
+	switch {
+	case p != "":
+		_, err = t.ParseFiles(p)
+	case p == "__full":
+		_, err = t.Parse(fullExportTemplate)
+	default:
+		_, err = t.Parse(defaultExportTemplate)
+	}
+
 	if err != nil {
 		return err
 	}

clab/graph.go

@@ -5,8 +5,10 @@
 package clab
 
 import (
+	"embed"
 	"fmt"
 	"html/template"
+	"io/fs"
 	"net/http"
 	"os"
 	"os/exec"
@@ -43,7 +45,7 @@ type TopoData struct {
 // noListFs embeds the http.Dir to override the Open method of a filesystem
 // to prevent listing of static files, see https://github.com/srl-labs/containerlab/pull/802#discussion_r815373751
 type noListFs struct {
-	http.Dir
+	http.FileSystem
 }
 
 var g *gographviz.Graph
@@ -154,7 +156,7 @@ func commandExists(cmd string) bool {
 // Open is a custom FS opener that prevents listing of the files in the filesystem
 // see https://github.com/srl-labs/containerlab/pull/802#discussion_r815373751
 func (nfs noListFs) Open(name string) (result http.File, err error) {
-	f, err := nfs.Dir.Open(name)
+	f, err := nfs.FileSystem.Open(name)
 	if err != nil {
 		return
 	}
@@ -246,24 +248,44 @@ func (c *CLab) GenerateMermaidGraph(direction string) error {
 	return nil
 }
 
+//go:embed graph_templates/nextui/nextui.html
+var defaultTemplate string
+
+//go:embed graph_templates/nextui/static
+var defaultStatic embed.FS
+
 func (c *CLab) ServeTopoGraph(tmpl, staticDir, srv string, topoD TopoData) error {
 	var t *template.Template
 
-	if !utils.FileExists(tmpl) {
+	if tmpl == "" {
+		t = template.Must(template.New("nextui.html").Parse(defaultTemplate))
+	} else if utils.FileExists(tmpl) {
+		t = template.Must(template.ParseFiles(tmpl))
+	} else {
 		return fmt.Errorf("%w. Path %s", e.ErrFileNotFound, tmpl)
 	}
-	t = template.Must(template.ParseFiles(tmpl))
 
-	if staticDir != "" {
-		if tmpl == "" {
-			return fmt.Errorf("the --static-dir flag must be used with the --template flag")
+	if staticDir != "" && tmpl == "" {
+		return fmt.Errorf("the --static-dir flag must be used with the --template flag")
+	}
+
+	var staticFS http.FileSystem
+	if staticDir == "" {
+		// extract the sub fs with static files from the embedded fs
+		subFS, err := fs.Sub(defaultStatic, "graph_templates/nextui/static")
+		if err != nil {
+			return err
 		}
 
-		fs := http.FileServer(noListFs{http.Dir(staticDir)})
-		http.Handle("/static/", http.StripPrefix("/static/", fs))
+		staticFS = http.FS(subFS)
+	} else {
 		log.Infof("Serving static files from directory: %s", staticDir)
+		staticFS = http.Dir(staticDir)
 	}
 
+	fs := http.FileServer(noListFs{staticFS})
+	http.Handle("/static/", http.StripPrefix("/static/", fs))
+
 	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
 		_ = t.Execute(w, topoD)
 	})

cmd/deploy.go

@@ -18,11 +18,6 @@ import (
 	"github.com/srl-labs/containerlab/runtime"
 )
 
-const (
-	// file name of a topology export data.
-	defaultExportTemplateFPath = "/etc/containerlab/templates/export/auto.tmpl"
-)
-
 // name of the container management network.
 var mgmtNetName string
 
@@ -74,7 +69,7 @@ func init() {
 		"limit the maximum number of workers creating nodes and virtual wires")
 	deployCmd.Flags().BoolVarP(&skipPostDeploy, "skip-post-deploy", "", false, "skip post deploy action")
 	deployCmd.Flags().StringVarP(&exportTemplate, "export-template", "",
-		defaultExportTemplateFPath, "template file for topology data export")
+		"", "template file for topology data export")
 	deployCmd.Flags().StringSliceVarP(&nodeFilter, "node-filter", "", []string{},
 		"comma separated list of nodes to include")
 	deployCmd.Flags().BoolVarP(&skipLabDirFileACLs, "skip-labdir-acl", "", false,

cmd/graph.go

@@ -19,11 +19,6 @@ import (
 	"github.com/srl-labs/containerlab/types"
 )
 
-const (
-	defaultGraphTemplatePath = "/etc/containerlab/templates/graph/nextui/nextui.html"
-	defaultStaticPath        = "/etc/containerlab/templates/graph/nextui/static"
-)
-
 var (
 	srv              string
 	tmpl             string
@@ -159,9 +154,9 @@ func init() {
 	graphCmd.Flags().BoolVarP(&drawio, "drawio", "", false, "generate drawio diagram file")
 	graphCmd.Flags().StringVarP(&drawioVersion, "drawio-version", "", "latest",
 		"version of the clab-io-draw container to use for generating drawio diagram file")
-	graphCmd.Flags().StringVarP(&tmpl, "template", "", defaultGraphTemplatePath,
+	graphCmd.Flags().StringVarP(&tmpl, "template", "", "",
 		"Go html template used to generate the graph")
-	graphCmd.Flags().StringVarP(&staticDir, "static-dir", "", defaultStaticPath,
+	graphCmd.Flags().StringVarP(&staticDir, "static-dir", "", "",
 		"Serve static files from the specified directory")
 	graphCmd.Flags().StringSliceVarP(&nodeFilter, "node-filter", "", []string{},
 		"comma separated list of nodes to include")

docs/cmd/deploy.md

@@ -110,9 +110,9 @@ The default timeout is set to 2 minutes and can be changed to values like `30s,
 
 #### export-template
 
-The local `--export-template` flag allows a user to specify a custom Go template that will be used for exporting topology data into `topology-data.json` file under the lab directory. If not set, the default template path is `/etc/containerlab/templates/export/auto.tmpl`.
+The local `--export-template` flag allows a user to specify a custom Go template that will be used for exporting topology data into `topology-data.json` file under the lab directory. If not set, the [default template](https://github.com/srl-labs/containerlab/blob/main/clab/export_templates/auto.tmpl) is used.
 
-To export full topology data instead of a subset of fields exported by default, use `--export-template /etc/containerlab/templates/export/full.tmpl`. Note, some fields exported via `full.tmpl` might contain sensitive information like TLS private keys. To customize export data, it is recommended to start with a copy of `auto.tmpl` and change it according to your needs.
+To export the full topology data instead of a subset of fields exported by default, use `--export-template __full` which is a special value that instructs containerlab to use the [full.tmpl](https://github.com/srl-labs/containerlab/blob/main/clab/export_templates/full.tmpl) template file. Note, some fields exported via `full.tmpl` might contain sensitive information like TLS private keys. To customize export data, it is recommended to start with a copy of `auto.tmpl` and change it according to your needs.
 
 #### log-level
 

docs/cmd/graph.md

@@ -110,7 +110,7 @@ A single path `/` is served, where the graph is generated based on either a defa
 
 ### template
 
-The `--template` flag allows to customize the HTML based graph by supplying a user defined template that will be rendered and exposed on the address specified by `--srv`.
+The `--template` flag allows to customize the HTML-based graph by supplying a user-defined template that will be rendered and exposed on the address specified by the `--srv`.
 
 ### static-dir