kata-env: Add ability to output as JSON

Having a direct JSON output for kata-env will help record
results in our CIs in some instances. Add that ability with
a kata-env command line extension.

Fixes: #474

Signed-off-by: Graham Whaley <graham.whaley@intel.com>

cli/kata-env.go

@@ -6,6 +6,7 @@
 package main
 
 import (
+	"encoding/json"
 	"errors"
 	"os"
 	"strings"
@@ -328,28 +329,17 @@ func getEnvInfo(configFile string, config oci.RuntimeConfig) (env EnvInfo, err e
 	return env, nil
 }
 
-func showSettings(env EnvInfo, file *os.File) error {
-	encoder := toml.NewEncoder(file)
-
-	err := encoder.Encode(env)
-	if err != nil {
-		return err
-	}
-
-	return nil
-}
-
-func handleSettings(file *os.File, metadata map[string]interface{}) error {
+func handleSettings(file *os.File, c *cli.Context) error {
 	if file == nil {
 		return errors.New("Invalid output file specified")
 	}
 
-	configFile, ok := metadata["configFile"].(string)
+	configFile, ok := c.App.Metadata["configFile"].(string)
 	if !ok {
 		return errors.New("cannot determine config file")
 	}
 
-	runtimeConfig, ok := metadata["runtimeConfig"].(oci.RuntimeConfig)
+	runtimeConfig, ok := c.App.Metadata["runtimeConfig"].(oci.RuntimeConfig)
 	if !ok {
 		return errors.New("cannot determine runtime config")
 	}
@@ -359,13 +349,29 @@ func handleSettings(file *os.File, metadata map[string]interface{}) error {
 		return err
 	}
 
-	return showSettings(env, file)
+	if c.Bool("json") {
+		encoder := json.NewEncoder(file)
+		// Make it more human readable
+		encoder.SetIndent("", "  ")
+		return encoder.Encode(env)
+	}
+
+	// Default to toml output
+	encoder := toml.NewEncoder(file)
+
+	return encoder.Encode(env)
 }
 
 var kataEnvCLICommand = cli.Command{
 	Name:  envCmd,
-	Usage: "display settings",
+	Usage: "display settings. Default to TOML",
+	Flags: []cli.Flag{
+		cli.BoolFlag{
+			Name:  "json",
+			Usage: "Format output as JSON",
+		},
+	},
 	Action: func(context *cli.Context) error {
-		return handleSettings(defaultOutputFile, context.App.Metadata)
+		return handleSettings(defaultOutputFile, context)
 	},
 }

cli/kata-env_test.go

@@ -906,6 +906,13 @@ func TestEnvCLIFunction(t *testing.T) {
 
 	err = fn(ctx)
 	assert.NoError(t, err)
+
+	set := flag.NewFlagSet("", 0)
+	set.Bool("json", true, "")
+	ctx := cli.NewContext(app, set, nil)
+
+	err = fn(ctx)
+	assert.NoError(t, err)
 }
 
 func TestEnvCLIFunctionFail(t *testing.T) {