DeploymentConfiguration

Information about the CloudWatch alarms.

Type: DeploymentAlarms object

Required: No

The deployment circuit breaker determines whether a service deployment will fail if the service can't reach a steady state. If you use the deployment circuit breaker, a service deployment will transition to a failed state and stop launching new tasks. If you use the rollback option, when a service deployment fails, the service is rolled back to the last deployment that completed successfully. For more information, see Rolling update in the Amazon Elastic Container Service Developer Guide

Type: DeploymentCircuitBreaker object

Required: No

If a service is using the rolling update (ECS) deployment type, the maximumPercent parameter represents an upper limit on the number of your service's tasks that are allowed in the RUNNING or PENDING state during a deployment, as a percentage of the desiredCount (rounded down to the nearest integer). This parameter enables you to define the deployment batch size. For example, if your service is using the REPLICA service scheduler and has a desiredCount of four tasks and a maximumPercent value of 200%, the scheduler may start four new tasks before stopping the four older tasks (provided that the cluster resources required to do this are available). The default maximumPercent value for a service using the REPLICA service scheduler is 200%.

The Amazon ECS scheduler uses this parameter to replace unhealthy tasks by starting replacement tasks first and then stopping the unhealthy tasks, as long as cluster resources for starting replacement tasks are available. For more information about how the scheduler replaces unhealthy tasks, see Amazon ECS services.

If a service is using either the blue/green (CODE_DEPLOY) or EXTERNAL deployment types, and tasks in the service use the EC2 launch type, the maximum percent value is set to the default value. The maximum percent value is used to define the upper limit on the number of the tasks in the service that remain in the RUNNING state while the container instances are in the DRAINING state.

If the service uses either the blue/green (CODE_DEPLOY) or EXTERNAL deployment types, and the tasks in the service use the Fargate launch type, the maximum percent value is not used. The value is still returned when describing your service.

Type: Integer

Required: No

If a service is using the rolling update (ECS) deployment type, the minimumHealthyPercent represents a lower limit on the number of your service's tasks that must remain in the RUNNING state during a deployment, as a percentage of the desiredCount (rounded up to the nearest integer). This parameter enables you to deploy without using additional cluster capacity. For example, if your service has a desiredCount of four tasks and a minimumHealthyPercent of 50%, the service scheduler may stop two existing tasks to free up cluster capacity before starting two new tasks.

If any tasks are unhealthy and if maximumPercent doesn't allow the Amazon ECS scheduler to start replacement tasks, the scheduler stops the unhealthy tasks one-by-one — using the minimumHealthyPercent as a constraint — to clear up capacity to launch replacement tasks. For more information about how the scheduler replaces unhealthy tasks, see Amazon ECS services .

For services that do not use a load balancer, the following should be noted:

For services that do use a load balancer, the following should be noted:

The default value for a replica service for minimumHealthyPercent is 100%. The default minimumHealthyPercent value for a service using the DAEMON service schedule is 0% for the AWS CLI, the AWS SDKs, and the APIs and 50% for the AWS Management Console.

The minimum number of healthy tasks during a deployment is the desiredCount multiplied by the minimumHealthyPercent/100, rounded up to the nearest integer value.

If a service is using either the blue/green (CODE_DEPLOY) or EXTERNAL deployment types and is running tasks that use the EC2 launch type, the minimum healthy percent value is set to the default value. The minimum healthy percent value is used to define the lower limit on the number of the tasks in the service that remain in the RUNNING state while the container instances are in the DRAINING state.

If a service is using either the blue/green (CODE_DEPLOY) or EXTERNAL deployment types and is running tasks that use the Fargate launch type, the minimum healthy percent value is not used, although it is returned when describing your service.

Type: Integer

Required: No