Class: Aws::ECS::Types::HealthCheck

Inherits:
Struct
  • Object
show all
Includes:
Structure
Defined in:
lib/aws-sdk-ecs/types.rb

Overview

An object representing a container health check. Health check parameters that are specified in a container definition override any Docker health checks that exist in the container image (such as those specified in a parent image or from the image’s Dockerfile). This configuration maps to the ‘HEALTHCHECK` parameter of docker run.

<note markdown=“1”> The Amazon ECS container agent only monitors and reports on the health checks specified in the task definition. Amazon ECS does not monitor Docker health checks that are embedded in a container image and not specified in the container definition. Health check parameters that are specified in a container definition override any Docker health checks that exist in the container image.

</note>

You can view the health status of both individual containers and a task with the DescribeTasks API operation or when viewing the task details in the console.

The health check is designed to make sure that your containers survive agent restarts, upgrades, or temporary unavailability.

Amazon ECS performs health checks on containers with the default that launched the container instance or the task.

The following describes the possible ‘healthStatus` values for a container:

  • ‘HEALTHY`-The container health check has passed successfully.

  • ‘UNHEALTHY`-The container health check has failed.

  • ‘UNKNOWN`-The container health check is being evaluated, there’s no container health check defined, or Amazon ECS doesn’t have the health status of the container.

The following describes the possible ‘healthStatus` values based on the container health checker status of essential containers in the task with the following priority order (high to low):

  • ‘UNHEALTHY`-One or more essential containers have failed their health check.

  • ‘UNKNOWN`-Any essential container running within the task is in an `UNKNOWN` state and no other essential containers have an `UNHEALTHY` state.

  • ‘HEALTHY`-All essential containers within the task have passed their health checks.

Consider the following task health example with 2 containers.

  • If Container1 is ‘UNHEALTHY` and Container2 is `UNKNOWN`, the task health is `UNHEALTHY`.

  • If Container1 is ‘UNHEALTHY` and Container2 is `HEALTHY`, the task health is `UNHEALTHY`.

  • If Container1 is ‘HEALTHY` and Container2 is `UNKNOWN`, the task health is `UNKNOWN`.

  • If Container1 is ‘HEALTHY` and Container2 is `HEALTHY`, the task health is `HEALTHY`.

Consider the following task health example with 3 containers.

  • If Container1 is ‘UNHEALTHY` and Container2 is `UNKNOWN`, and Container3 is `UNKNOWN`, the task health is `UNHEALTHY`.

  • If Container1 is ‘UNHEALTHY` and Container2 is `UNKNOWN`, and Container3 is `HEALTHY`, the task health is `UNHEALTHY`.

  • If Container1 is ‘UNHEALTHY` and Container2 is `HEALTHY`, and Container3 is `HEALTHY`, the task health is `UNHEALTHY`.

  • If Container1 is ‘HEALTHY` and Container2 is `UNKNOWN`, and Container3 is `HEALTHY`, the task health is `UNKNOWN`.

  • If Container1 is ‘HEALTHY` and Container2 is `UNKNOWN`, and Container3 is `UNKNOWN`, the task health is `UNKNOWN`.

  • If Container1 is ‘HEALTHY` and Container2 is `HEALTHY`, and Container3 is `HEALTHY`, the task health is `HEALTHY`.

If a task is run manually, and not as part of a service, the task will continue its lifecycle regardless of its health status. For tasks that are part of a service, if the task reports as unhealthy then the task will be stopped and the service scheduler will replace it.

The following are notes about container health check support:

  • If the Amazon ECS container agent becomes disconnected from the Amazon ECS service, this won’t cause a container to transition to an ‘UNHEALTHY` status. This is by design, to ensure that containers remain running during agent restarts or temporary unavailability. The health check status is the “last heard from” response from the Amazon ECS agent, so if the container was considered `HEALTHY` prior to the disconnect, that status will remain until the agent reconnects and another health check occurs. There are no assumptions made about the status of the container health checks.

  • Container health checks require version ‘1.17.0` or greater of the Amazon ECS container agent. For more information, see [Updating the Amazon ECS container agent].

  • Container health checks are supported for Fargate tasks if you’re using platform version ‘1.1.0` or greater. For more information, see [Fargate platform versions].

  • Container health checks aren’t supported for tasks that are part of a service that’s configured to use a Classic Load Balancer.

[1]: docs.aws.amazon.com/AmazonECS/latest/developerguide/ecs-agent-update.html [2]: docs.aws.amazon.com/AmazonECS/latest/developerguide/platform_versions.html

See Also:

Constant Summary collapse

SENSITIVE = 
[]

Instance Attribute Summary collapse

Instance Attribute Details

#command ⇒ Array<String>

A string array representing the command that the container runs to determine if it is healthy. The string array must start with ‘CMD` to run the command arguments directly, or `CMD-SHELL` to run the command with the container’s default shell.

When you use the Amazon Web Services Management Console JSON panel, the Command Line Interface, or the APIs, enclose the list of commands in double quotes and brackets.

‘[ “CMD-SHELL”, “curl -f localhost/ || exit 1” ]`

You don’t include the double quotes and brackets when you use the Amazon Web Services Management Console.

‘ CMD-SHELL, curl -f localhost/ || exit 1`

An exit code of 0 indicates success, and non-zero exit code indicates failure. For more information, see ‘HealthCheck` in the docker container create command

Returns:

  • (Array<String>) 


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# File 'lib/aws-sdk-ecs/types.rb', line 5259

class HealthCheck < Struct.new(
  :command,
  :interval,
  :timeout,
  :retries,
  :start_period)
  SENSITIVE = []
  include Aws::Structure
end

#interval ⇒ Integer

The time period in seconds between each health check execution. You may specify between 5 and 300 seconds. The default value is 30 seconds.

Returns:

  • (Integer) 


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# File 'lib/aws-sdk-ecs/types.rb', line 5259

class HealthCheck < Struct.new(
  :command,
  :interval,
  :timeout,
  :retries,
  :start_period)
  SENSITIVE = []
  include Aws::Structure
end

#retries ⇒ Integer

The number of times to retry a failed health check before the container is considered unhealthy. You may specify between 1 and 10 retries. The default value is 3.

Returns:

  • (Integer) 


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# File 'lib/aws-sdk-ecs/types.rb', line 5259

class HealthCheck < Struct.new(
  :command,
  :interval,
  :timeout,
  :retries,
  :start_period)
  SENSITIVE = []
  include Aws::Structure
end

#start_period ⇒ Integer

The optional grace period to provide containers time to bootstrap before failed health checks count towards the maximum number of retries. You can specify between 0 and 300 seconds. By default, the ‘startPeriod` is off.

<note markdown=“1”> If a health check succeeds within the ‘startPeriod`, then the container is considered healthy and any subsequent failures count toward the maximum number of retries.

</note>

Returns:

  • (Integer) 


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# File 'lib/aws-sdk-ecs/types.rb', line 5259

class HealthCheck < Struct.new(
  :command,
  :interval,
  :timeout,
  :retries,
  :start_period)
  SENSITIVE = []
  include Aws::Structure
end

#timeout ⇒ Integer

The time period in seconds to wait for a health check to succeed before it is considered a failure. You may specify between 2 and 60 seconds. The default value is 5.

Returns:

  • (Integer) 


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# File 'lib/aws-sdk-ecs/types.rb', line 5259

class HealthCheck < Struct.new(
  :command,
  :interval,
  :timeout,
  :retries,
  :start_period)
  SENSITIVE = []
  include Aws::Structure
end