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/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")