feat: add --format json support to ps:scale

The `ps:scale` command now accepts a `--format` flag that defaults to `stdout` and can be set to `json` to emit the current formation as a JSON array of process type and quantity objects, matching the JSON output the `:report` subcommands already provide. The flag only applies when displaying the current formation; it is ignored when process types are supplied for scaling. When no scale has been set for the app, the JSON output is an empty array.

plugins/ps/functions.go

@@ -1,6 +1,7 @@
 package ps
 
 import (
+	"encoding/json"
 	"errors"
 	"fmt"
 	"os"
@@ -243,12 +244,22 @@ func restorePrep() error {
 	return nil
 }
 
-func scaleReport(appName string) error {
+func scaleReport(appName string, format string) error {
 	formations, err := getFormations(appName)
 	if err != nil {
 		return err
 	}
 
+	if format == "json" {
+		out, err := json.Marshal(formations)
+		if err != nil {
+			return err
+		}
+
+		common.Log(string(out))
+		return nil
+	}
+
 	common.LogInfo1Quiet(fmt.Sprintf("Scaling for %s", appName))
 
 	content := []string{}

plugins/ps/src/commands/commands.go

@@ -23,7 +23,7 @@ Additional commands:`
     ps:report [<app>] [<flag>], Displays a process report for one or more apps
     ps:restart [--parallel count] [--all|<app>] [<process-name>], Restart an app
     ps:restore [<app>], Start previously running apps e.g. after reboot
-    ps:scale [--skip-deploy] <app> <proc>=<count> [<proc>=<count>...], Get/Set how many instances of a given process to run
+    ps:scale [--skip-deploy] [--format stdout|json] <app> [<proc>=<count>...], Get/Set how many instances of a given process to run
     ps:set <app> <key> <value>, Set or clear a ps property for an app
     ps:start [--parallel count] [--all|<app>], Start an app
     ps:stop [--parallel count] [--all|<app>], Stop an app

plugins/ps/src/subcommands/subcommands.go

@@ -65,10 +65,11 @@ func main() {
 	case "scale":
 		args := flag.NewFlagSet("ps:scale", flag.ExitOnError)
 		skipDeploy := args.Bool("skip-deploy", false, "--skip-deploy: skip deploy of the app")
+		format := args.String("format", "stdout", "format: [ stdout | json ]")
 		args.Parse(os.Args[2:])
 		appName := args.Arg(0)
 		_, processTuples := common.ShiftString(args.Args())
-		err = ps.CommandScale(appName, *skipDeploy, processTuples)
+		err = ps.CommandScale(appName, *skipDeploy, *format, processTuples)
 	case "set":
 		args := flag.NewFlagSet("ps:set", flag.ExitOnError)
 		global := args.Bool("global", false, "--global: set a global property")

plugins/ps/subcommands.go

@@ -158,13 +158,13 @@ func CommandRetire(appName string) error {
 }
 
 // CommandScale gets or sets how many instances of a given process to run
-func CommandScale(appName string, skipDeploy bool, processTuples []string) error {
+func CommandScale(appName string, skipDeploy bool, format string, processTuples []string) error {
 	if err := common.VerifyAppName(appName); err != nil {
 		return err
 	}
 
 	if len(processTuples) == 0 {
-		return scaleReport(appName)
+		return scaleReport(appName, format)
 	}
 
 	if !canScaleApp(appName) {