Running synchronous processes (#1)

Using the -w / --wait parameter, it waits for the task to finish.

Author: meap

README.md

@@ -2,6 +2,8 @@
 
 RunECS is a tool for running one-off processes in an ECS cluster. The tool was created as a simple solution for occasional running of processes in the ECS cluster - e.g. various data migrations. Currently only the FARGATE launch type is supported.
 
+The process can be started asynchronously (does not wait for finish) or synchronously with the `-w` parameter (waits for task finish).
+
 ## How to Use
 
 The ECS cluster settings are located in the `~/.runecs.yml` file, which is located in the user's home directory. The default profile is called `default` and is automatically used unless explicitly specified otherwise.

cmd/main.go

@@ -26,8 +26,9 @@ import (
 )
 
 var (
-	profile string
-	verbose bool
+	profile  string
+	verbose  bool
+	execWait bool
 )
 
 var runCmd = &cobra.Command{
@@ -36,7 +37,7 @@ var runCmd = &cobra.Command{
 	Args:  cobra.MinimumNArgs(1),
 	Run: func(cmd *cobra.Command, args []string) {
 		svc := initService()
-		svc.Execute(args)
+		svc.Execute(args, execWait)
 	},
 }
 
@@ -58,6 +59,8 @@ func init() {
 	rootCmd.PersistentFlags().BoolVarP(&verbose, "verbose", "", false, "verbose output")
 	rootCmd.CompletionOptions.DisableDefaultCmd = true
 
+	runCmd.PersistentFlags().BoolVarP(&execWait, "wait", "w", false, "wait for the task to finish")
+
 	rootCmd.AddCommand(runCmd)
 	rootCmd.AddCommand(deregisterCmd)
 }

pkg/ecs/exec.go

@@ -3,6 +3,7 @@ package ecs
 import (
 	"context"
 	"log"
+	"time"
 
 	"github.com/aws/aws-sdk-go-v2/service/ecs"
 	"github.com/aws/aws-sdk-go-v2/service/ecs/types"
@@ -29,6 +30,7 @@ func (s *Service) describeService(client *ecs.Client) (serviceDef, error) {
 	}
 
 	def := resp.Services[0]
+	log.Printf("Service '%s' loaded.", *def.ServiceName)
 
 	return serviceDef{
 		Subnets:        def.NetworkConfiguration.AwsvpcConfiguration.Subnets,
@@ -45,7 +47,7 @@ func (s *Service) describeTask(client *ecs.Client, taskArn *string) taskDef {
 	}
 }
 
-func (s *Service) Execute(cmd []string) {
+func (s *Service) Execute(cmd []string, wait bool) {
 	cfg, err := s.initCfg()
 	if err != nil {
 		log.Fatalln(err)
@@ -84,4 +86,29 @@ func (s *Service) Execute(cmd []string) {
 	}
 
 	log.Printf("Task %s executed.", *output.Tasks[0].TaskArn)
+	if wait {
+		for {
+			success := s.wait(svc, *output.Tasks[0].TaskArn)
+			if success {
+				break
+			}
+
+			time.Sleep(6 * time.Second)
+		}
+
+		log.Printf("Task %s finished.", *output.Tasks[0].TaskArn)
+	}
+}
+
+func (s *Service) wait(client *ecs.Client, task string) bool {
+	output, err := client.DescribeTasks(context.TODO(), &ecs.DescribeTasksInput{
+		Cluster: &s.Cluster,
+		Tasks:   []string{task},
+	})
+
+	if err != nil {
+		log.Fatalln(err)
+	}
+
+	return *output.Tasks[0].LastStatus == "STOPPED"
 }