aws-ecs: Support MaxSwap and Swappiness in LinuxParameters

[joelchen]

Description

Please support MaxSwap (https://github.com/aws/aws-cdk/blob/master/packages/@aws-cdk/cfnspec/spec-source/specification/000_cfn/000_official/000_AWS_ECS.json#L975) and Swappiness (https://github.com/aws/aws-cdk/blob/master/packages/@aws-cdk/cfnspec/spec-source/specification/000_cfn/000_official/000_AWS_ECS.json#L987) in LinuxParameters (https://github.com/aws/aws-cdk/blob/master/packages/@aws-cdk/aws-ecs/lib/linux-parameters.ts).

Use Case

Using swap allows the container to write excess memory requirements to disk when the container has exhausted all the RAM that is available to it.

Proposed Solution

export interface LinuxParametersProps {
  /**
   * Specifies whether to run an init process inside the container that forwards signals and reaps processes.
   *
   * @default false
   */
  readonly initProcessEnabled?: boolean;

  /**
   * The value for the size (in MiB) of the /dev/shm volume.
   *
   * @default No shared memory.
   */
  readonly sharedMemorySize?: number;

  /**
   * The total amount of swap memory (in MiB) a container can use.
   *
   * @default No swap.
   */
  readonly maxSwap?: number;

  /**
   * This allows you to tune a container's memory swappiness behavior.
   *
   * @default 60
   */
  readonly swappiness?: number;
}

constructor(scope: Construct, id: string, props: LinuxParametersProps = {}) {
  super(scope, id);

  this.sharedMemorySize = props.sharedMemorySize;
  this.initProcessEnabled = props.initProcessEnabled;
  this.maxSwap = props.maxSwap;
  this.swappiness = props.swappiness;
}

Other information

No response

Acknowledge

• I may be able to implement this feature request
• This feature might incur a breaking change

[mjgp2]

Example workaround:

// https://github.com/aws/aws-cdk/issues/18460
export class LinuxParams extends LinuxParameters {

  renderLinuxParameters(): ecs.CfnTaskDefinition.LinuxParametersProperty {
      const p = super.renderLinuxParameters() as any;
      p.maxSwap = 5e3;
      p.swappiness = 0;
      return p;
  }
}

[joelchen]

@mjgp2 Thank you, it got registered in repository's template.json and tree.json. However after deployment, docker inspect the running container of bottlerocket-os shows MemorySwappiness with new value but MemorySwap is 0.

[mjgp2]

@joelchen - you probably need to enable some swap space on the EC2 host instance.

[github-actions]

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