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Amazon EC2 Container Service
API Reference (API Version 2014-11-13)

UpdateService

Modifies the desired count, deployment configuration, or task definition used in a service.

You can add to or subtract from the number of instantiations of a task definition in a service by specifying the cluster that the service is running in and a new desiredCount parameter.

You can use UpdateService to modify your task definition and deploy a new version of your service.

You can also update the deployment configuration of a service. When a deployment is triggered by updating the task definition of a service, the service scheduler uses the deployment configuration parameters, minimumHealthyPercent and maximumPercent, to determine the deployment strategy.

  • If minimumHealthyPercent is below 100%, the scheduler can ignore desiredCount temporarily during a deployment. For example, if desiredCount is four tasks, a minimum of 50% allows the scheduler to stop two existing tasks before starting two new tasks. Tasks for services that do not use a load balancer are considered healthy if they are in the RUNNING state. Tasks for services that use a load balancer are considered healthy if they are in the RUNNING state and the container instance they are hosted on is reported as healthy by the load balancer.

  • The maximumPercent parameter represents an upper limit on the number of running tasks during a deployment, which enables you to define the deployment batch size. For example, if desiredCount is four tasks, a maximum of 200% starts four new tasks before stopping the four older tasks (provided that the cluster resources required to do this are available).

When UpdateService stops a task during a deployment, the equivalent of docker stop is issued to the containers running in the task. This results in a SIGTERM and a 30-second timeout, after which SIGKILL is sent and the containers are forcibly stopped. If the container handles the SIGTERM gracefully and exits within 30 seconds from receiving it, no SIGKILL is sent.

When the service scheduler launches new tasks, it determines task placement in your cluster with the following logic:

  • Determine which of the container instances in your cluster can support your service's task definition (for example, they have the required CPU, memory, ports, and container instance attributes).

  • By default, the service scheduler attempts to balance tasks across Availability Zones in this manner (although you can choose a different placement strategy):

    • Sort the valid container instances by the fewest number of running tasks for this service in the same Availability Zone as the instance. For example, if zone A has one running service task and zones B and C each have zero, valid container instances in either zone B or C are considered optimal for placement.

    • Place the new service task on a valid container instance in an optimal Availability Zone (based on the previous steps), favoring container instances with the fewest number of running tasks for this service.

When the service scheduler stops running tasks, it attempts to maintain balance across the Availability Zones in your cluster using the following logic:

  • Sort the container instances by the largest number of running tasks for this service in the same Availability Zone as the instance. For example, if zone A has one running service task and zones B and C each have two, container instances in either zone B or C are considered optimal for termination.

  • Stop the task on a container instance in an optimal Availability Zone (based on the previous steps), favoring container instances with the largest number of running tasks for this service.

Request Syntax

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{ "cluster": "string", "deploymentConfiguration": { "maximumPercent": number, "minimumHealthyPercent": number }, "desiredCount": number, "service": "string", "taskDefinition": "string" }

Request Parameters

For information about the parameters that are common to all actions, see Common Parameters.

The request accepts the following data in JSON format.

cluster

The short name or full Amazon Resource Name (ARN) of the cluster that your service is running on. If you do not specify a cluster, the default cluster is assumed.

Type: String

Required: No

deploymentConfiguration

Optional deployment parameters that control how many tasks run during the deployment and the ordering of stopping and starting tasks.

Type: DeploymentConfiguration object

Required: No

desiredCount

The number of instantiations of the task to place and keep running in your service.

Type: Integer

Required: No

service

The name of the service to update.

Type: String

Required: Yes

taskDefinition

The family and revision (family:revision) or full Amazon Resource Name (ARN) of the task definition to run in your service. If a revision is not specified, the latest ACTIVE revision is used. If you modify the task definition with UpdateService, Amazon ECS spawns a task with the new version of the task definition and then stops an old task after the new version is running.

Type: String

Required: No

Response Syntax

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{ "service": { "clusterArn": "string", "createdAt": number, "deploymentConfiguration": { "maximumPercent": number, "minimumHealthyPercent": number }, "deployments": [ { "createdAt": number, "desiredCount": number, "id": "string", "pendingCount": number, "runningCount": number, "status": "string", "taskDefinition": "string", "updatedAt": number } ], "desiredCount": number, "events": [ { "createdAt": number, "id": "string", "message": "string" } ], "loadBalancers": [ { "containerName": "string", "containerPort": number, "loadBalancerName": "string", "targetGroupArn": "string" } ], "pendingCount": number, "placementConstraints": [ { "expression": "string", "type": "string" } ], "placementStrategy": [ { "field": "string", "type": "string" } ], "roleArn": "string", "runningCount": number, "serviceArn": "string", "serviceName": "string", "status": "string", "taskDefinition": "string" } }

Response Elements

If the action is successful, the service sends back an HTTP 200 response.

The following data is returned in JSON format by the service.

service

The full description of your service following the update call.

Type: Service object

Errors

For information about the errors that are common to all actions, see Common Errors.

ClientException

These errors are usually caused by a client action, such as using an action or resource on behalf of a user that doesn't have permission to use the action or resource, or specifying an identifier that is not valid.

HTTP Status Code: 400

ClusterNotFoundException

The specified cluster could not be found. You can view your available clusters with ListClusters. Amazon ECS clusters are region-specific.

HTTP Status Code: 400

InvalidParameterException

The specified parameter is invalid. Review the available parameters for the API request.

HTTP Status Code: 400

ServerException

These errors are usually caused by a server issue.

HTTP Status Code: 500

ServiceNotActiveException

The specified service is not active. You cannot update a service that is not active. If you have previously deleted a service, you can re-create it with CreateService.

HTTP Status Code: 400

ServiceNotFoundException

The specified service could not be found. You can view your available services with ListServices. Amazon ECS services are cluster-specific and region-specific.

HTTP Status Code: 400

Example

In the following example or examples, the Authorization header contents (AUTHPARAMS) must be replaced with an AWS Signature Version 4 signature. For more information about creating these signatures, see Signature Version 4 Signing Process in the AWS General Reference.

You only need to learn how to sign HTTP requests if you intend to manually create them. When you use the AWS Command Line Interface (AWS CLI) or one of the AWS SDKs to make requests to AWS, these tools automatically sign the requests for you with the access key that you specify when you configure the tools. When you use these tools, you don't need to learn how to sign requests yourself.

Example

This example request updates the hello_world service to a desired count of 3.

Sample Request

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POST / HTTP/1.1 Host: ecs.us-east-1.amazonaws.com Accept-Encoding: identity Content-Length: 45 X-Amz-Target: AmazonEC2ContainerServiceV20141113.UpdateService X-Amz-Date: 20150429T194543Z Content-Type: application/x-amz-json-1.1 Authorization: AUTHPARAMS { "service": "hello_world", "desiredCount": 3 }

Sample Response

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HTTP/1.1 200 OK Server: Server Date: Wed, 29 Apr 2015 19:45:43 GMT Content-Type: application/x-amz-json-1.1 Content-Length: 13376 Connection: keep-alive x-amzn-RequestId: 123a4b56-7c89-01d2-3ef4-example5678f { "service": { "clusterArn": "arn:aws:ecs:us-east-1:012345678910:cluster/default", "deploymentConfiguration": { "maximumPercent": 200, "minimumHealthyPercent": 100 }, "deployments": [ { "createdAt": 1430333711.033, "desiredCount": 3, "id": "ecs-svc/9223370606521064774", "pendingCount": 0, "runningCount": 0, "status": "PRIMARY", "taskDefinition": "arn:aws:ecs:us-east-1:012345678910:task-definition/hello_world:10", "updatedAt": 1430336267.173 } ], "desiredCount": 3, "events": [], "loadBalancers": [], "pendingCount": 0, "runningCount": 0, "serviceArn": "arn:aws:ecs:us-east-1:012345678910:service/hello_world", "serviceName": "hello_world", "status": "ACTIVE", "taskDefinition": "arn:aws:ecs:us-east-1:012345678910:task-definition/hello_world:10" } }

See Also

For more information about using this API in one of the language-specific AWS SDKs, see the following: