support output-dir when running 'helm template' (#3144)

* support output-dir when running 'helm template'

* add --output-dir to documentation

* when writing to file, dont add additional document

* trigger another ci build. make test-unit works for me

* dont write blank files

* return err instead of panic

cmd/helm/template.go

@@ -21,6 +21,7 @@ import (
 	"fmt"
 	"io"
 	"os"
+	"path"
 	"path/filepath"
 	"regexp"
 	"strings"
@@ -39,6 +40,10 @@ import (
 	tversion "k8s.io/helm/pkg/version"
 )
 
+const defaultDirectoryPermission = 0755
+
+var whitespaceRegex = regexp.MustCompile(`^\s*$`)
+
 const templateDesc = `
 Render chart templates locally and display the output.
 
@@ -64,6 +69,7 @@ type templateCmd struct {
 	releaseName  string
 	renderFiles  []string
 	kubeVersion  string
+	outputDir    string
 }
 
 func newTemplateCmd(out io.Writer) *cobra.Command {
@@ -88,6 +94,7 @@ func newTemplateCmd(out io.Writer) *cobra.Command {
 	f.StringArrayVar(&t.values, "set", []string{}, "set values on the command line (can specify multiple or separate values with commas: key1=val1,key2=val2)")
 	f.StringVar(&t.nameTemplate, "name-template", "", "specify template used to name the release")
 	f.StringVar(&t.kubeVersion, "kube-version", "", "override the Kubernetes version used as Capabilities.KubeVersion.Major/Minor (e.g. 1.7)")
+	f.StringVar(&t.outputDir, "output-dir", "", "writes the executed templates to files in output-dir instead of stdout")
 
 	return cmd
 }
@@ -126,6 +133,14 @@ func (t *templateCmd) run(cmd *cobra.Command, args []string) error {
 		}
 	}
 
+	// verify that output-dir exists if provided
+	if t.outputDir != "" {
+		_, err = os.Stat(t.outputDir)
+		if os.IsNotExist(err) {
+			return fmt.Errorf("output-dir '%s' does not exist", t.outputDir)
+		}
+	}
+
 	if t.namespace == "" {
 		t.namespace = defaultNamespace()
 	}
@@ -248,8 +263,61 @@ func (t *templateCmd) run(cmd *cobra.Command, args []string) error {
 		if strings.HasPrefix(b, "_") {
 			continue
 		}
+
+		if t.outputDir != "" {
+			// blank template after execution
+			if whitespaceRegex.MatchString(data) {
+				continue
+			}
+			err = writeToFile(t.outputDir, m.Name, data)
+			if err != nil {
+				return err
+			}
+			continue
+		}
 		fmt.Printf("---\n# Source: %s\n", m.Name)
 		fmt.Println(data)
 	}
 	return nil
 }
+
+// write the <data> to <output-dir>/<name>
+func writeToFile(outputDir string, name string, data string) error {
+	outfileName := strings.Join([]string{outputDir, name}, string(filepath.Separator))
+
+	err := ensureDirectoryForFile(outfileName)
+	if err != nil {
+		return err
+	}
+
+	f, err := os.Create(outfileName)
+	if err != nil {
+		return err
+	}
+
+	defer f.Close()
+
+	_, err = f.WriteString(fmt.Sprintf("##---\n# Source: %s\n%s", name, data))
+
+	if err != nil {
+		return err
+	}
+
+	fmt.Printf("wrote %s\n", outfileName)
+	return nil
+}
+
+// check if the directory exists to create file. creates if don't exists
+func ensureDirectoryForFile(file string) error {
+	baseDir := path.Dir(file)
+	_, err := os.Stat(baseDir)
+	if err != nil && !os.IsNotExist(err) {
+		return err
+	}
+
+	err = os.MkdirAll(baseDir, defaultDirectoryPermission)
+	if err != nil {
+		return err
+	}
+	return nil
+}

docs/helm/helm_template.md

@@ -31,6 +31,7 @@ helm template [flags] CHART
       --name-template string   specify template used to name the release
       --namespace string       namespace to install the release into
       --notes                  show the computed NOTES.txt file as well
+      --output-dir string      writes the executed templates to files in output-dir instead of stdout
       --set stringArray        set values on the command line (can specify multiple or separate values with commas: key1=val1,key2=val2)
   -f, --values valueFiles      specify values in a YAML file (can specify multiple) (default [])
 ```
@@ -49,4 +50,4 @@ helm template [flags] CHART
 ### SEE ALSO
 * [helm](helm.md)	 - The Helm package manager for Kubernetes.
 
-###### Auto generated by spf13/cobra on 7-Nov-2017
+###### Auto generated by spf13/cobra on 15-Nov-2017