Windows EC2 memory hog

Windows EC2 memory hog induces memory stress on the target AWS Windows EC2 instance using Amazon SSM Run command. The SSM Run command is executed using SSM documentation that is built into the fault. This fault causes memory exhaustion on the target Windows EC2 instance for a specific duration.

Use cases

Windows EC2 memory hog:

• Causes memory stress on the target AWS EC2 instance(s).
• Simulates the situation of memory leaks in the deployment of microservices.
• Simulates application slowness due to memory starvation, and noisy neighbour problems due to hogging.

Prerequisites

• Kubernetes >= 1.17
• The EC2 instance must be in a healthy state.
• SSM agent must be installed and running on the target EC2 Windows instance in the admin mode.
• SSM IAM role must be attached to the target EC2 instance(s).
• Kubernetes secret must have the AWS Access Key ID and Secret Access Key credentials in the CHAOS_NAMESPACE. Below is a sample secret file:

  apiVersion: v1
  kind: Secret
  metadata:
    name: cloud-secret
  type: Opaque
  stringData:
    cloud_config.yml: |-
      # Add the cloud AWS credentials respectively
      [default]
      aws_access_key_id = XXXXXXXXXXXXXXXXXXX
      aws_secret_access_key = XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

tip

HCE recommends that you use the same secret name, that is, cloud-secret. Otherwise, you will need to update the AWS_SHARED_CREDENTIALS_FILE environment variable in the fault template with the new secret name and you won't be able to use the default health check probes.

Below is an example AWS policy to execute the fault.

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Effect": "Allow",
            "Action": [
                "ssm:GetDocument",
                "ssm:DescribeDocument",
                "ssm:GetParameter",
                "ssm:GetParameters",
                "ssm:SendCommand",
                "ssm:CancelCommand",
                "ssm:CreateDocument",
                "ssm:DeleteDocument",
                "ssm:GetCommandInvocation",
                "ssm:UpdateInstanceInformation",
                "ssm:DescribeInstanceInformation"
            ],
            "Resource": "*"
        },
        {
            "Effect": "Allow",
            "Action": [
                "ec2messages:AcknowledgeMessage",
                "ec2messages:DeleteMessage",
                "ec2messages:FailMessage",
                "ec2messages:GetEndpoint",
                "ec2messages:GetMessages",
                "ec2messages:SendReply"
            ],
            "Resource": "*"
        },
        {
            "Effect": "Allow",
            "Action": [
                "ec2:DescribeInstanceStatus",
                "ec2:DescribeInstances"
            ],
            "Resource": [
                "*"
            ]
        }
    ]
}

note

• Go to AWS named profile for chaos to use a different profile for AWS faults.

Mandatory tunables

Tunable	Description	Notes
EC2_INSTANCE_ID	ID of the target EC2 instance.	For example, i-044d3cb4b03b8af1f. For more information, go to EC2 instances.
REGION	AWS region ID where the EC2 instance has been created.	For example, us-east-1.

Optional tunables

Tunable	Description	Notes
TOTAL_CHAOS_DURATION	Duration that you specify, through which chaos is injected into the target resource (in seconds).	Default: 30 s. For more information, go to duration of the chaos.
AWS_SHARED_CREDENTIALS_FILE	Path to the AWS secret credentials.	Defaults to /tmp/cloud_config.yml.
INSTALL_DEPENDENCIES	Install dependencies to run the network chaos. It can be 'True' or 'False'.	If the dependency already exists, you can turn it off. Default: True.
MEMORY_CONSUMPTION	Amount of memory to be consumed by the EC2 instance (in megabytes).	Default: 0 MB. For more information, go to memory consumption in MB.
MEMORY_PERCENTAGE	Amount of memory to be consumed by the EC2 instance (in percentage).	Default: 50. For more information, go to memory consumption by percentage.
SEQUENCE	Sequence of chaos execution for multiple instances.	Default: parallel. Supports serial and parallel. For more information, go to sequence of chaos execution.
RAMP_TIME	Period to wait before and after injecting chaos (in seconds).	For example, 30 s. For more information, go to ramp time.

Memory consumption in megabytes

Memory utilized on the EC2 instance (in megabytes). Tune it by using the MEMORY_CONSUMPTION environment variable.

The following YAML snippet illustrates the use of this environment variable:

# memory in mb to utilize
apiVersion: litmuschaos.io/v1alpha1
kind: ChaosEngine
metadata:
  name: engine-nginx
spec:
  engineState: "active"
  chaosServiceAccount: litmus-admin
  experiments:
  - name: windows-ec2-memory-hog
    spec:
      components:
        env:
        - name: MEMORY_CONSUMPTION
          VALUE: '1024'
        # ID of the EC2 instance
        - name: EC2_INSTANCE_ID
          value: 'instance-1'
        # region for the EC2 instance
        - name: REGION
          value: 'us-east-1'

Memory consumption by percentage

Memory utilized on the EC2 instance (in percentage). Tune it by using the MEMORY_PERCENTAGE environment variable.

The following YAML snippet illustrates the use of this environment variable:

# memory percentage to utilize
apiVersion: litmuschaos.io/v1alpha1
kind: ChaosEngine
metadata:
  name: engine-nginx
spec:
  engineState: "active"
  chaosServiceAccount: litmus-admin
  experiments:
  - name: windows-ec2-memory-hog
    spec:
      components:
        env:
        - name: MEMORY_PERCENTAGE
          value: '50'
        - name: MEMORY_CONSUMPTION
          value: '0'
        # ID of the EC2 instance
        - name: EC2_INSTANCE_ID
          value: 'instance-1'
        # region for the EC2 instance
        - name: REGION
          value: 'us-east-1'

Multiple EC2 instances

Multiple EC2 instances specified as comma-separated IDs targeted in one chaos run. Tune it by using the EC2_INSTANCE_ID environment variable.

The following YAML snippet illustrates the use of this environment variable:

# multiple instance targets
apiVersion: litmuschaos.io/v1alpha1
kind: ChaosEngine
metadata:
  name: engine-nginx
spec:
  engineState: "active"
  chaosServiceAccount: litmus-admin
  experiments:
  - name: windows-ec2-memory-hog
    spec:
      components:
        env:
        # ids of the EC2 instances
        - name: EC2_INSTANCE_ID
          value: 'instance-1,instance-2,instance-3'
        # region for the EC2 instance
        - name: REGION
          value: 'us-east-1'