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EC2 stop by ID

EC2 stop by ID stops an EC2 instance using the provided instance ID or list of instance IDs and brings back the instance after a specific duration. When the MANAGED_NODEGROUP environment variable is enabled, the fault will not try to start the instance after chaos. Instead, it checks for the addition of a new node instance to the cluster.

EC2 Stop By ID

Use cases​

EC2 stop by ID:

  • Determines the performance of the application (or process) running on the EC2 instance.
  • Determines the resilience of an application to unexpected halts in the EC2 instance by validating its failover capabilities.

Prerequisites​

  • Kubernetes >= 1.17
  • Access to start and stop an EC2 instance in AWS.
  • The EC2 instance should be in a healthy state.
  • The Kubernetes secret should have the AWS access configuration(key) in the CHAOS_NAMESPACE. Below is the 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 = XXXXXXXXXXXXXXX
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": [
                "ec2:StartInstances",
                "ec2:StopInstances",
                "ec2:DescribeInstanceStatus",
                "ec2:DescribeInstances"
            ],
            "Resource": "*"
        },
        {
            "Effect": "Allow",
            "Action": [
                "autoscaling:DescribeAutoScalingInstances"
            ],
            "Resource": "*"
        }
    ]
}
note

Mandatory tunables​

Tunable Description Notes
EC2_INSTANCE_ID Instance ID of the target EC2 instance. Multiple IDs can also be provided as a comma(,) separated values. Multiple IDs can be provided as id1,id2. For more information, go to EC2 instance ID.
REGION The region name of the target instance.

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. Default: /tmp/cloud_config.yml.
CHAOS_INTERVAL The interval (in sec) between successive instance termination. Default: 30 s. For more information, go to chaos interval.
MANAGED_NODEGROUP Set to enable if the target instance is the part of self-managed nodegroups. Defaults to disable.
SEQUENCE It defines sequence of chaos execution for multiple instance. Defaults to 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.
warning

If the target EC2 instance is a part of a managed node group, drain the target node of any application running on it. Isolate the target node before running the fault so that the faulty pods are not scheduled on it.

Stop instances By ID​

Comma-separated list of target instance IDs. Tune it by using the EC2_INSTANCE_ID environment variable.

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

# contains the instance id, to be terminated/stopped
apiVersion: litmuschaos.io/v1alpha1
kind: ChaosEngine
metadata:
  name: engine-nginx
spec:
  engineState: "active"
  chaosServiceAccount: litmus-admin
  experiments:
  - name: ec2-terminate-by-id
    spec:
      components:
        env:
        # ID of the EC2 instance
        - name: EC2_INSTANCE_ID
          value: 'instance-1'
        # region for the EC2 instance
        - name: REGION
          value: 'us-east-1'