feat: add json output to config:export

This change adds json output as both key/value as well as a list of objects. The former can be used in quick scripting environments, while the latter allows higher-level languages to have a bit more structure around how environment variables are declared. Specifically, systems such as kubernetes understand the latter method, while the former can be used within Nomad job files.

plugins/config/environment.go

@@ -1,17 +1,16 @@
 package config
 
 import (
+	"archive/tar"
+	"encoding/json"
 	"errors"
 	"fmt"
 	"io"
+	"os"
 	"path/filepath"
 	"sort"
 	"strings"
 
-	"archive/tar"
-
-	"os"
-
 	"github.com/dokku/dokku/plugins/common"
 	"github.com/joho/godotenv"
 	"github.com/ryanuber/columnize"
@@ -31,6 +30,10 @@ const (
 	ExportFormatShell
 	//ExportFormatPretty format: pretty-printed in columns
 	ExportFormatPretty
+	//ExportFormatJSON format: json key/value output
+	ExportFormatJSON
+	//ExportFormatJSONList format: json output as a list of objects
+	ExportFormatJSONList
 )
 
 //Env is a representation for global or app environment
@@ -168,6 +171,10 @@ func (e *Env) Export(format ExportFormat) string {
 		return e.ShellString()
 	case ExportFormatPretty:
 		return prettyPrintEnvEntries("", e.Map())
+	case ExportFormatJSON:
+		return e.JSONString()
+	case ExportFormatJSONList:
+		return e.JSONListString()
 	default:
 		common.LogFail(fmt.Sprintf("Unknown export format: %v", format))
 		return ""
@@ -190,6 +197,35 @@ func (e *Env) DockerArgsString() string {
 	return e.stringWithPrefixAndSeparator("--env=", " ")
 }
 
+//JSONString returns the contents of this Env as a key/value json object
+func (e *Env) JSONString() string {
+	data, err := json.Marshal(e.Map())
+	if err != nil {
+		return "{}"
+	}
+
+	return string(data)
+}
+
+//JSONListString returns the contents of this Env as a json list of objects containing the name and the value of the env var
+func (e *Env) JSONListString() string {
+	var list []map[string]string
+	for _, key := range e.Keys() {
+		value, _ := e.Get(key)
+		list = append(list, map[string]string{
+			"name":  key,
+			"value": value,
+		})
+	}
+
+	data, err := json.Marshal(list)
+	if err != nil {
+		return "[]"
+	}
+
+	return string(data)
+}
+
 //ShellString gets the contents of this Env in the form "KEY='value' KEY2='value'"
 // for passing the environment in the shell
 func (e *Env) ShellString() string {

plugins/config/src/subcommands/export/export.go

@@ -14,7 +14,7 @@ func main() {
 	args := flag.NewFlagSet("config:export", flag.ExitOnError)
 	global := args.Bool("global", false, "--global: use the global environment")
 	merged := args.Bool("merged", false, "--merged: merge app environment and global environment")
-	format := args.String("format", "exports", "--format: [ exports | envfile | docker-args | shell ] which format to export as)")
+	format := args.String("format", "exports", "--format: [ exports | envfile | docker-args | shell | pretty | json | json-list ] which format to export as)")
 	args.Parse(os.Args[2:])
 	config.CommandExport(args.Args(), *global, *merged, *format)
 }

plugins/config/subcommands.go

@@ -117,6 +117,10 @@ func CommandExport(args []string, global bool, merged bool, format string) {
 		suffix = " "
 	case "pretty":
 		exportType = ExportFormatPretty
+	case "json":
+		exportType = ExportFormatJSON
+	case "json-list":
+		exportType = ExportFormatJSONList
 	default:
 		common.LogFail(fmt.Sprintf("Unknown export format: %v", format))
 	}

tests/unit/20_config.bats

@@ -155,6 +155,32 @@ teardown() {
   run /bin/bash -c "dokku --app $TEST_APP config:show"
   echo "output: $output"
   echo "status: "$stat
-
   assert_output "=====> $TEST_APP env vars"$'\nBKEY:  true\naKey:  true\nbKey:  true\nzKey:  true'
 }
+
+@test "(config) config:export" {
+  run /bin/bash -c "dokku --app $TEST_APP config:set zKey=true bKey=true BKEY=true aKey=true"
+  echo "output: $output"
+  echo "status: $status"
+  assert_success
+
+  run /bin/bash -c "dokku config:export --format docker-args $TEST_APP"
+  echo "output: $output"
+  echo "status: "$stat
+  assert_output "--env=BKEY='true' --env=aKey='true' --env=bKey='true' --env=zKey='true'"
+
+  run /bin/bash -c "dokku config:export --format shell $TEST_APP"
+  echo "output: $output"
+  echo "status: "$stat
+  assert_output "BKEY='true' aKey='true' bKey='true' zKey='true' "
+
+  run /bin/bash -c "dokku config:export --format json $TEST_APP"
+  echo "output: $output"
+  echo "status: "$stat
+  assert_output '{"BKEY":"true","aKey":"true","bKey":"true","zKey":"true"}'
+
+  run /bin/bash -c "dokku config:export --format json-list $TEST_APP"
+  echo "output: $output"
+  echo "status: "$stat
+  assert_output '[{"name":"BKEY","value":"true"},{"name":"aKey","value":"true"},{"name":"bKey","value":"true"},{"name":"zKey","value":"true"}]'
+}