feat: allow specifying a single process type to restart

This changes restarts to drop the 'release' part that currently gets triggered, which also helps reduce the possibility that a new image layer will be added due to predeploy deploy triggers.

Note that the old method essentially halfway-rebuilt the app (which was what added the extra layer). This refactor removes that, which is a bc-break.

Additionally, scaling processes will result in deploying _only_ restarting the processes being scaled.

Closes #2184

plugins/ps/functions.go

@@ -282,12 +282,18 @@ func scaleSet(appName string, skipDeploy bool, clearExisting bool, processTuples
 		return nil
 	}
 
-	imageTag, err := common.GetRunningImageTag(appName)
+	imageTag, err := common.GetRunningImageTag(appName, "")
 	if err != nil {
 		return err
 	}
 
-	return common.PlugnTrigger("release-and-deploy", []string{appName, imageTag}...)
+	for _, formation := range formations {
+		if err := common.PlugnTrigger("deploy", []string{appName, imageTag, formation.ProcessType}...); err != nil {
+			return err
+		}
+	}
+
+	return nil
 }
 
 func updateScale(appName string, clearExisting bool, formationUpdates FormationSlice) error {

plugins/ps/ps.go

@@ -57,7 +57,37 @@ func Restart(appName string) error {
 		return nil
 	}
 
-	return common.PlugnTrigger("release-and-deploy", []string{appName}...)
+	imageTag, err := common.GetRunningImageTag(appName, "")
+	if err != nil {
+		return err
+	}
+
+	if imageTag == "" {
+		common.LogWarn("No deployed-image-tag property saved, falling back to full release-and-deploy")
+		return common.PlugnTrigger("release-and-deploy", []string{appName}...)
+	}
+
+	return common.PlugnTrigger("deploy", []string{appName, imageTag}...)
+}
+
+// RestartProcess restarts a process type within an app
+func RestartProcess(appName string, processName string) error {
+	if !common.IsDeployed(appName) {
+		common.LogWarn(fmt.Sprintf("App %s has not been deployed", appName))
+		return nil
+	}
+
+	imageTag, err := common.GetRunningImageTag(appName, "")
+	if err != nil {
+		return err
+	}
+
+	if imageTag == "" {
+		common.LogWarn("No deployed-image-tag property saved, falling back to full release-and-deploy")
+		return common.PlugnTrigger("release-and-deploy", []string{appName}...)
+	}
+
+	return common.PlugnTrigger("deploy", []string{appName, imageTag, processName}...)
 }
 
 // Restore ensures an app that should be running is running on boot
@@ -90,7 +120,7 @@ func Restore(appName string) error {
 
 // Start starts the app
 func Start(appName string) error {
-	imageTag, _ := common.GetRunningImageTag(appName)
+	imageTag, _ := common.GetRunningImageTag(appName, "")
 
 	if !common.IsDeployed(appName) {
 		common.LogWarn(fmt.Sprintf("App %s has not been deployed", appName))

plugins/ps/src/commands/commands.go

@@ -21,7 +21,7 @@ Additional commands:`
     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:report [<app>] [<flag>], Displays a process report for one or more apps
-    ps:restart [--parallel count] [--all|<app>], 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:scale [--skip-deploy] <app> <proc>=<count> [<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

plugins/ps/src/subcommands/subcommands.go

@@ -45,7 +45,8 @@ func main() {
 		parallelCount := args.Int("parallel", ps.RunInSerial, "--parallel: number of apps to restart in parallel, -1 to match cpu count")
 		args.Parse(os.Args[2:])
 		appName := args.Arg(0)
-		err = ps.CommandRestart(appName, *allApps, *parallelCount)
+		processName := args.Arg(1)
+		err = ps.CommandRestart(appName, processName, *allApps, *parallelCount)
 	case "restore":
 		args := flag.NewFlagSet("ps:restore", flag.ExitOnError)
 		allApps := args.Bool("all", false, "--all: restore all apps")

plugins/ps/subcommands.go

@@ -54,8 +54,11 @@ func CommandReport(appName string, format string, infoFlag string) error {
 }
 
 // CommandRestart restarts an app
-func CommandRestart(appName string, allApps bool, parallelCount int) error {
+func CommandRestart(appName string, processName string, allApps bool, parallelCount int) error {
 	if allApps {
+		if processName != "" {
+			return errors.New("Unable to restart all apps when specifying a process name")
+		}
 		return common.RunCommandAgainstAllApps(Restart, "restart", parallelCount)
 	}
 
@@ -63,6 +66,10 @@ func CommandRestart(appName string, allApps bool, parallelCount int) error {
 		return err
 	}
 
+	if processName != "" {
+		return RestartProcess(appName, processName)
+	}
+
 	return Restart(appName)
 }