feat: add ability to set maintenance mode for all cron tasks running for an app

Closes #6953

docs/processes/scheduled-cron-tasks.md

@@ -53,39 +53,39 @@ When running scheduled cron tasks, there are a few items to be aware of:
 - Scheduled cron tasks are supported on a per-scheduler basis, and are currently only implemented by the `docker-local` scheduler.
 - Tasks for _all_ apps managed by the `docker-local` scheduler are written to a single crontab file owned by the `dokku` user. The `dokku` user's crontab should be considered reserved for this purpose.
 
-#### Specifying a MAILFROM value
 
-> [!IMPORTANT]
-> New as of 0.35.14
+### Changing cron management settings
 
-Users can specify a value for `MAILFROM` via the global `mailfrom` cron property by using the `cron:set` command.
+The `cron` 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:
+
+| Name                  | Description                                                    | Level       | Global Default |
+|-----------------------|----------------------------------------------------------------|-------------|----------------|
+| `mailfrom`            | Sets the `MAILFROM` variable in a cron file for cron reporting | Global-only | empty string   |
+| `maintenance`         | Whether to have cron running for the app or not.               | App-only    | `false`        |
+| `mailto`              | Sets the `MAILTO` variable in a cron file for cron reporting   | Global-only | empty string   |
+
+All settings can be set via the `ps:set` command. Using `maintenance` as an example:
 
 ```shell
-dokku cron:set --global mailfrom example@example.com
+dokku ps:set node-js-app maintenance true
 ```
 
-All output for individual cron runs will be sent from the specified email.
-
-Cron emails can be reset to use the system email by running the `cron:set` command for the global `mailfrom` property with no value.
+The default value may be set by passing an empty value for the option in question:
 
 ```shell
-dokku cron:set --global mailfrom
+dokku ps:set node-js-app maintenance
 ```
 
-#### Specifying a MAILTO value
-
-By default, cron tasks complete and do not perform any reporting. Users can specify a value for `MAILTO` via the global `mailto` cron property by using the `cron:set` command.
+If a property can be set globally - such as `mailto`, use the `--global` flag. If not set for an app, the global value will apply if it exists.
 
 ```shell
-dokku cron:set --global mailto example@example.com
+dokku ps:set --global maintenance true
 ```
 
-All output for individual cron runs will be sent to the specified email.
-
-Cron emails can be disabled by running the `cron:set` command for the global `mailto` property with no value.
+The global default value may be set by passing an empty value for the option.
 
 ```shell
-dokku cron:set --global mailto
+dokku ps:set --global maintenance
 ```
 
 #### Listing Cron tasks

plugins/cron/Makefile

@@ -1,5 +1,5 @@
 SUBCOMMANDS = subcommands/list subcommands/report subcommands/run subcommands/set
-TRIGGERS = triggers/cron-get-property
+TRIGGERS = triggers/cron-get-property triggers/install triggers/post-app-clone-setup triggers/post-app-rename-setup triggers/post-delete triggers/scheduler-stop
 BUILD = commands subcommands triggers
 PLUGIN_NAME = cron
 

plugins/cron/cron.go

@@ -12,14 +12,16 @@ import (
 var (
 	// DefaultProperties is a map of all valid cron properties with corresponding default property values
 	DefaultProperties = map[string]string{
-		"mailfrom": "",
-		"mailto":   "",
+		"mailfrom":    "",
+		"mailto":      "",
+		"maintenance": "false",
 	}
 
 	// GlobalProperties is a map of all valid global cron properties
 	GlobalProperties = map[string]bool{
-		"mailfrom": true,
-		"mailto":   true,
+		"mailfrom":    true,
+		"mailto":      true,
+		"maintenance": true,
 	}
 )
 
@@ -59,6 +61,10 @@ func (t TemplateCommand) CronCommand() string {
 // FetchCronEntries returns a list of cron commands for a given app
 func FetchCronEntries(appName string) ([]TemplateCommand, error) {
 	commands := []TemplateCommand{}
+	if reportComputedMaintenance(appName) == "true" {
+		return commands, nil
+	}
+
 	appJSON, err := appjson.GetAppJSON(appName)
 	if err != nil {
 		return commands, fmt.Errorf("Unable to fetch app.json for app %s: %s", appName, err.Error())

plugins/cron/report.go

@@ -13,9 +13,12 @@ func ReportSingleApp(appName string, format string, infoFlag string) error {
 	}
 
 	flags := map[string]common.ReportFunc{
-		"--cron-mailfrom":   reportMailfrom,
-		"--cron-mailto":     reportMailto,
-		"--cron-task-count": reportTasks,
+		"--cron-mailfrom":             reportMailfrom,
+		"--cron-mailto":               reportMailto,
+		"--cron-task-count":           reportTasks,
+		"--cron-global-maintenance":   reportGlobalMaintenance,
+		"--cron-computed-maintenance": reportComputedMaintenance,
+		"--cron-maintenance":          reportMaintenance,
 	}
 
 	flagKeys := []string{}
@@ -41,3 +44,20 @@ func reportTasks(appName string) string {
 	c, _ := FetchCronEntries(appName)
 	return strconv.Itoa(len(c))
 }
+
+func reportGlobalMaintenance(_ string) string {
+	return common.PropertyGet("cron", "--global", "maintenance")
+}
+
+func reportComputedMaintenance(appName string) string {
+	maintenance := common.PropertyGet("cron", appName, "maintenance")
+	if maintenance == "true" {
+		return "true"
+	}
+
+	return common.PropertyGetDefault("cron", "--global", "maintenance", DefaultProperties["maintenance"])
+}
+
+func reportMaintenance(appName string) string {
+	return common.PropertyGet("cron", appName, "maintenance")
+}

plugins/cron/src/triggers/triggers.go

@@ -43,6 +43,11 @@ func main() {
 	case "report":
 		appName := flag.Arg(0)
 		err = cron.ReportSingleApp(appName, "", "")
+	case "scheduler-stop":
+		scheduler := flag.Arg(0)
+		appName := flag.Arg(1)
+		removeContainers := flag.Arg(2)
+		err = cron.TriggerSchedulerStop(scheduler, appName, removeContainers)
 	default:
 		err = fmt.Errorf("Invalid plugin trigger call: %s", trigger)
 	}

plugins/cron/triggers.go

@@ -10,14 +10,16 @@ import (
 // TriggerCronGetProperty writes the cron key to stdout for a given app container
 func TriggerCronGetProperty(appName string, key string) error {
 	validProperties := map[string]bool{
-		"mailfrom": true,
-		"mailto":   true,
+		"mailfrom":    true,
+		"mailto":      true,
+		"maintenance": true,
 	}
 	if !validProperties[key] {
 		return errors.New("Invalid cron property specified")
 	}
 
-	fmt.Println(common.PropertyGet("cron", appName, key))
+	value := common.PropertyGetDefault("cron", appName, key, DefaultProperties[key])
+	fmt.Println(value)
 	return nil
 }
 
@@ -57,3 +59,12 @@ func TriggerPostAppRenameSetup(oldAppName string, newAppName string) error {
 func TriggerPostDelete(appName string) error {
 	return common.PropertyDestroy("cron", appName)
 }
+
+// TriggerSchedulerStop stops the scheduler for a given app container
+func TriggerSchedulerStop(scheduler string, appName string, removeContainers string) error {
+	if scheduler != "docker-local" {
+		return nil
+	}
+
+	return nil
+}