Merge pull request #35 from stormcat24/feature/keep_desired_count

Add option of keep desired_count at updating service

README.md

@@ -108,6 +108,21 @@ test-service:
       container_port: 80
 ```
 
+#### Keep desired_count at updating service
+
+If you modify value of `desired_count` by AWS Management Console or aws-cli, you'll fear override value of `desired_count` by ecs-formation. This value should be flexibly changed in the operation.
+
+If `keep_desired_count` is `true`, keep current `desired_count` at updating service.
+
+```bash
+(path-to-path/test-ecs-formation/service) $ vim test-cluster.yml
+test-service:
+  task_definition: test-definition
+  desired_count: 1
+  keep_desired_count: true
+```
+
+
 #### Manage Task Definitions
 
 Show update plan.

operation/service.go

@@ -120,6 +120,7 @@ func createClusterPlans(controller *service.ServiceController, projectDir string
 			util.PrintlnYellow(fmt.Sprintf("        ----------[%s]----------", add.Name))
 			util.PrintlnYellow(fmt.Sprintf("        TaskDefinition = %s", add.TaskDefinition))
 			util.PrintlnYellow(fmt.Sprintf("        DesiredCount = %d", add.DesiredCount))
+			util.PrintlnYellow(fmt.Sprintf("        KeepDesiredCount = %t", add.KeepDesiredCount))
 			for _, lb := range add.LoadBalancers {
 				util.PrintlnYellow(fmt.Sprintf("        ELB:%s", lb.Name))
 			}

service/schema.go

@@ -5,25 +5,24 @@ import (
 )
 
 type Cluster struct {
-
-	Name	string
-	Services	map[string]Service
+	Name     string
+	Services map[string]Service
 }
 
 type Service struct {
-
-	Name	string
-	TaskDefinition	string	`yaml:"task_definition"`
-	DesiredCount	int64	`yaml:"desired_count"`
-	LoadBalancers	[]LoadBalancer	`yaml:"load_balancers"`
-	Role	string	`yaml:"role"`
+	Name             string
+	TaskDefinition   string         `yaml:"task_definition"`
+	DesiredCount     int64          `yaml:"desired_count"`
+	KeepDesiredCount bool           `yaml:"keep_desired_count"`
+	LoadBalancers    []LoadBalancer `yaml:"load_balancers"`
+	Role             string         `yaml:"role"`
 }
 
 func (self *Service) FindLoadBalancerByContainer(conname string, port int64) *LoadBalancer {
 
 	for _, lb := range self.LoadBalancers {
 		if lb.ContainerName == conname &&
-		lb.ContainerPort == port {
+			lb.ContainerPort == port {
 			return &lb
 		}
 	}
@@ -42,10 +41,9 @@ func (self *Service) FindLoadBalancerByName(name string) *LoadBalancer {
 }
 
 type LoadBalancer struct {
-
-	Name	string	`yaml:"name"`
-	ContainerName	string	`yaml:"container_name"`
-	ContainerPort	int64	`yaml:"container_port"`
+	Name          string `yaml:"name"`
+	ContainerName string `yaml:"container_name"`
+	ContainerPort int64  `yaml:"container_port"`
 }
 
 func CreateServiceMap(data []byte) (map[string]Service, error) {
@@ -59,4 +57,4 @@ func CreateServiceMap(data []byte) (map[string]Service, error) {
 	}
 
 	return servicesMap, err
-}
+}

service/service.go

@@ -181,7 +181,10 @@ func (self *ServiceController) ApplyServicePlan(plan *ServiceUpdatePlan) error {
 
 	api := self.manager.EcsApi()
 
+	currentSizeMap := make(map[string]int64, 0)
+
 	for _, current := range plan.CurrentServices {
+		currentSizeMap[*current.ServiceName] = *current.DesiredCount
 
 		// set desired_count = 0
 		if _, err := api.UpdateService(plan.Name, *current.ServiceName, 0, *current.TaskDefinition); err != nil {
@@ -210,7 +213,19 @@ func (self *ServiceController) ApplyServicePlan(plan *ServiceUpdatePlan) error {
 
 	for _, add := range plan.NewServices {
 
-		result, err := api.CreateService(plan.Name, add.Name, add.DesiredCount, toLoadBalancers(&add.LoadBalancers), add.TaskDefinition, add.Role)
+		var nextDesiredCount int64
+		if add.KeepDesiredCount {
+			if dc, ok := currentSizeMap[add.Name]; ok {
+				nextDesiredCount = dc
+				logger.Main.Infof("Keep DesiredCount %d at '%s'", add.Name, nextDesiredCount)
+			} else {
+				nextDesiredCount = add.DesiredCount
+			}
+		} else {
+			nextDesiredCount = add.DesiredCount
+		}
+
+		result, err := api.CreateService(plan.Name, add.Name, nextDesiredCount, toLoadBalancers(&add.LoadBalancers), add.TaskDefinition, add.Role)
 		if err != nil {
 			return err
 		}