feat: first steps towards watchable ps output

See coop-cloud/organising#178.

cli/app/ps.go

@@ -3,6 +3,7 @@ package app
 import (
 	"fmt"
 	"strings"
+	"time"
 
 	abraFormatter "coopcloud.tech/abra/cli/formatter"
 	"coopcloud.tech/abra/cli/internal"
@@ -15,11 +16,50 @@ import (
 	"github.com/urfave/cli/v2"
 )
 
+var watch bool
+var watchFlag = &cli.BoolFlag{
+	Name:        "watch",
+	Aliases:     []string{"w"},
+	Value:       false,
+	Usage:       "Watch status by polling repeatedly",
+	Destination: &watch,
+}
+
 var appPsCommand = &cli.Command{
 	Name:    "ps",
 	Usage:   "Check app status",
 	Aliases: []string{"p"},
+	Flags: []cli.Flag{
+		watchFlag,
+	},
 	Action: func(c *cli.Context) error {
+		if !watch {
+			showPSOutput(c)
+			return nil
+		}
+
+		// TODO: how do we make this update in-place in an x-platform way?
+		for {
+			showPSOutput(c)
+			time.Sleep(2 * time.Second)
+		}
+	},
+	BashComplete: func(c *cli.Context) {
+		appNames, err := config.GetAppNames()
+		if err != nil {
+			logrus.Warn(err)
+		}
+		if c.NArg() > 0 {
+			return
+		}
+		for _, a := range appNames {
+			fmt.Println(a)
+		}
+	},
+}
+
+// showPSOutput renders ps output.
+func showPSOutput(c *cli.Context) {
 	app := internal.ValidateApp(c)
 
 	cl, err := client.New(app.Server)
@@ -56,18 +96,4 @@ var appPsCommand = &cli.Command{
 	}
 
 	table.Render()
-		return nil
-	},
-	BashComplete: func(c *cli.Context) {
-		appNames, err := config.GetAppNames()
-		if err != nil {
-			logrus.Warn(err)
-		}
-		if c.NArg() > 0 {
-			return
-		}
-		for _, a := range appNames {
-			fmt.Println(a)
-		}
-	},
 }