feat(helm): output flag for helm inspect to provide data as json values

output flag is added to `helm inspect`, so the output format type can be
set to json or yaml
eg: `helm inspect chart mychart/ --output=json`

closes: [5070](https://github.com/helm/helm/issues/5070)

Signed-off-by: Mohan Prasath <openmohan@gmail.com>

cmd/helm/inspect.go

@@ -17,12 +17,14 @@ limitations under the License.
 package main
 
 import (
+	"encoding/json"
 	"fmt"
+	"io"
+	"strings"
+
 	"github.com/ghodss/yaml"
 	"github.com/golang/protobuf/ptypes/any"
 	"github.com/spf13/cobra"
-	"io"
-	"strings"
 
 	"k8s.io/helm/pkg/chartutil"
 )
@@ -52,6 +54,7 @@ of the README file
 type inspectCmd struct {
 	chartpath    string
 	output       string
+	outputFormat string
 	verify       bool
 	keyring      string
 	out          io.Writer
@@ -70,6 +73,8 @@ const (
 	valuesOnly = "values"
 	readmeOnly = "readme"
 	all        = "all"
+	yamlFormat = "yaml"
+	jsonFormat = "json"
 )
 
 var readmeFileNames = []string{"readme.md", "readme.txt", "readme"}
@@ -211,6 +216,12 @@ func newInspectCmd(out io.Writer) *cobra.Command {
 		subCmd.Flags().StringVar(&insp.caFile, caFile, "", caFiledesc)
 	}
 
+	outputFormat := "output"
+	outputFormatDesc := "output represents the output format. One of: json|yaml"
+	inspectCommand.Flags().StringVar(&insp.outputFormat, outputFormat, yamlFormat, outputFormatDesc)
+	valuesSubCmd.Flags().StringVar(&insp.outputFormat, outputFormat, yamlFormat, outputFormatDesc)
+	chartSubCmd.Flags().StringVar(&insp.outputFormat, outputFormat, yamlFormat, outputFormatDesc)
+
 	for _, subCmd := range cmds[1:] {
 		inspectCommand.AddCommand(subCmd)
 	}
@@ -223,7 +234,17 @@ func (i *inspectCmd) run() error {
 	if err != nil {
 		return err
 	}
-	cf, err := yaml.Marshal(chrt.Metadata)
+
+	if err := i.validateFlags(); err != nil {
+		return err
+	}
+
+	var cf []byte
+	if i.outputFormat == yamlFormat {
+		cf, err = yaml.Marshal(chrt.Metadata)
+	} else {
+		cf, err = json.Marshal(chrt.Metadata)
+	}
 	if err != nil {
 		return err
 	}
@@ -236,7 +257,16 @@ func (i *inspectCmd) run() error {
 		if i.output == all {
 			fmt.Fprintln(i.out, "---")
 		}
-		fmt.Fprintln(i.out, chrt.Values.Raw)
+
+		cValues := []byte(chrt.Values.Raw)
+		if i.outputFormat == jsonFormat {
+			cValues, err = yaml.YAMLToJSON(cValues)
+			if err != nil {
+				return err
+			}
+		}
+
+		fmt.Fprintln(i.out, string(cValues))
 	}
 
 	if i.output == readmeOnly || i.output == all {
@@ -252,6 +282,13 @@ func (i *inspectCmd) run() error {
 	return nil
 }
 
+func (i *inspectCmd) validateFlags() error {
+	if i.outputFormat == jsonFormat || i.outputFormat == yamlFormat {
+		return nil
+	}
+	return fmt.Errorf("invalid output format provided =%s, expected values json,yaml", i.outputFormat)
+}
+
 func findReadme(files []*any.Any) (file *any.Any) {
 	for _, file := range files {
 		if containsString(readmeFileNames, strings.ToLower(file.TypeUrl), nil) {

cmd/helm/inspect_test.go

@@ -30,6 +30,7 @@ func TestInspect(t *testing.T) {
 		chartpath:    "testdata/testcharts/alpine",
 		output:       all,
 		out:          b,
+		outputFormat: "yaml",
 	}
 	insp.run()
 

docs/helm/helm_inspect.md

@@ -23,6 +23,7 @@ helm inspect [CHART] [flags]
   -h, --help               help for inspect
       --key-file string    identify HTTPS client using this SSL key file
       --keyring string     path to the keyring containing public verification keys (default "~/.gnupg/pubring.gpg")
+      --output string      output represents the output format. One of: json|yaml (default "yaml")
       --password string    chart repository password where to locate the requested chart
       --repo string        chart repository url where to locate the requested chart
       --username string    chart repository username where to locate the requested chart
@@ -49,4 +50,4 @@ helm inspect [CHART] [flags]
 * [helm inspect readme](helm_inspect_readme.md)	 - shows inspect readme
 * [helm inspect values](helm_inspect_values.md)	 - shows inspect values
 
-###### Auto generated by spf13/cobra on 1-Aug-2018
+###### Auto generated by spf13/cobra on 19-Dec-2018

docs/helm/helm_inspect_chart.md

@@ -21,6 +21,7 @@ helm inspect chart [CHART] [flags]
   -h, --help               help for chart
       --key-file string    identify HTTPS client using this SSL key file
       --keyring string     path to the keyring containing public verification keys (default "~/.gnupg/pubring.gpg")
+      --output string      output represents the output format. One of: json|yaml (default "yaml")
       --password string    chart repository password where to locate the requested chart
       --repo string        chart repository url where to locate the requested chart
       --username string    chart repository username where to locate the requested chart
@@ -44,4 +45,4 @@ helm inspect chart [CHART] [flags]
 
 * [helm inspect](helm_inspect.md)	 - inspect a chart
 
-###### Auto generated by spf13/cobra on 1-Aug-2018
+###### Auto generated by spf13/cobra on 19-Dec-2018

docs/helm/helm_inspect_values.md

@@ -21,6 +21,7 @@ helm inspect values [CHART] [flags]
   -h, --help               help for values
       --key-file string    identify HTTPS client using this SSL key file
       --keyring string     path to the keyring containing public verification keys (default "~/.gnupg/pubring.gpg")
+      --output string      output represents the output format. One of: json|yaml (default "yaml")
       --password string    chart repository password where to locate the requested chart
       --repo string        chart repository url where to locate the requested chart
       --username string    chart repository username where to locate the requested chart
@@ -44,4 +45,4 @@ helm inspect values [CHART] [flags]
 
 * [helm inspect](helm_inspect.md)	 - inspect a chart
 
-###### Auto generated by spf13/cobra on 1-Aug-2018
+###### Auto generated by spf13/cobra on 19-Dec-2018