Merge pull request #8796 from dokku/8793-add-format-json-support-to-ps-scale

Add --format json support to ps:scale

docs/processes/process-management.md

@@ -4,15 +4,15 @@
 > New as of 0.3.14, Enhanced in 0.7.0
 
 ```
-ps:inspect <app>                                                  # Displays a sanitized version of docker inspect for an app
+ps:inspect <app>                                                          # Displays a sanitized version of docker inspect for an app
-ps:rebuild [--parallel count] [--all|<app>]                       # Rebuilds an app from source
+ps:rebuild [--parallel count] [--all|<app>]                               # Rebuilds an app from source
-ps:report [<app>] [<flag>]                                        # Displays a process report for one or more apps
+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:restart [--parallel count] [--all|<app>]  [<process-name>]             # Restart an app
-ps:restore [<app>]                                                # Start previously running apps e.g. after reboot
+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:set <app> <key> <value>                                                # Set or clear a ps property for an app
-ps:start [--parallel count] [--all|<app>]                         # Start an app
+ps:start [--parallel count] [--all|<app>]                                 # Start an app
-ps:stop [--parallel count] [--all|<app>]                          # Stop an app
+ps:stop [--parallel count] [--all|<app>]                                  # Stop an app
 ```
 
 ## Usage
@@ -107,6 +107,18 @@ proctype: qty
 web:  1
 ```
 
+The formation can also be retrieved as JSON by using the `--format json` flag, which is useful for programmatic consumption. Each entry maps a process type to its desired quantity:
+
+```shell
+dokku ps:scale node-js-app --format json
+```
+
+```json
+[{"process_type":"web","quantity":1},{"process_type":"worker","quantity":4}]
+```
+
+When no scale has been set for the app, the JSON output is an empty array (`[]`).
+
 ### Changing process management settings
 
 The `ps` plugin provides a number of settings that can be used to managed deployments on a per-app basis. The following table outlines ones not covered elsewhere:

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) {

tests/unit/ps-general-1.bats

@@ -269,6 +269,42 @@ web
   assert_output $'beat: 0\nweb:  4\nworker: 1'
 }
 
+@test "(ps:scale) --format json" {
+  run /bin/bash -c "dokku ps:scale $TEST_APP --format json"
+  echo "output: $output"
+  echo "status: $status"
+  assert_success
+  assert_output '[{"process_type":"web","quantity":1}]'
+
+  echo "web=4
+worker=1" >/var/lib/dokku/config/ps/$TEST_APP/scale
+
+  run /bin/bash -c "dokku ps:scale $TEST_APP --format json | jq '. | length'"
+  echo "output: $output"
+  echo "status: $status"
+  assert_success
+  assert_output "2"
+
+  run /bin/bash -c "dokku ps:scale $TEST_APP --format json | jq -r '.[] | select(.process_type==\"web\") | .quantity'"
+  echo "output: $output"
+  echo "status: $status"
+  assert_success
+  assert_output "4"
+
+  run /bin/bash -c "dokku ps:scale $TEST_APP --format json | jq -r '.[] | select(.process_type==\"worker\") | .quantity'"
+  echo "output: $output"
+  echo "status: $status"
+  assert_success
+  assert_output "1"
+
+  rm -f /var/lib/dokku/config/ps/$TEST_APP/scale
+  run /bin/bash -c "dokku ps:scale $TEST_APP --format json"
+  echo "output: $output"
+  echo "status: $status"
+  assert_success
+  assert_output "[]"
+}
+
 @test "(ps) handle windows newlines in procfile" {
   run deploy_app python dokku@$DOKKU_DOMAIN:$TEST_APP procfile_line_endings_to_windows
   echo "output: $output"