helix/internal/stacks/templates.go

package stacks

import (
	"fmt"
	"os"
	"path/filepath"
	"strings"
	"text/template"
)

// renderTemplates renders all template files (.tmpl) within a given directory in the
// embedded 'templates' filesystem.
func renderTemplates(data interface{}, service, projectCacheRoot string) error {
	// create the context directory
	contextDir := filepath.Join(projectCacheRoot, service)

	if err := os.MkdirAll(contextDir, 0700); err != nil {
		return fmt.Errorf("unable to make the cache directory for %s...\n%w", service, err)
	}

	// read the service's template directory to get the list of the template files.
	templateDir := "templates/" + service

	fsDir, err := templates.ReadDir(templateDir)
	if err != nil {
		return err
	}

	// render each template file (.tmpl) to the context directory.
	for _, f := range fsDir {
		filename := f.Name()

		content, err := templates.ReadFile(fmt.Sprintf("%s/%s", templateDir, filename))
		if err != nil {
			return err
		}

		outputFilename := strings.TrimSuffix(filename, ".tmpl")
		outputPath := filepath.Join(contextDir, outputFilename)

		file, err := os.Create(outputPath)
		if err != nil {
			return fmt.Errorf("unable to create the file '%s'...\n%v", outputPath, err)
		}
		defer file.Close()

		if !strings.HasSuffix(filename, ".tmpl") {
			fmt.Fprint(file, string(content))
			return nil
		}

		tmpl := template.Must(template.New(filename).Parse(string(content)))

		if err = tmpl.Execute(file, data); err != nil {
			return fmt.Errorf("unable to execute the template at '%s'...\n%v", outputFilename, err)
		}
	}

	return nil
}