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EBS loss by ID

EBS (Elastic Block Store) loss by ID disrupts the state of EBS volume by detaching it from the node (or EC2) instance using volume ID for a certain duration. In case of EBS persistent volumes, the volumes can self-attach, and the re-attachment step can be skipped.

EBS Loss By ID

Use cases​

EBS loss by ID tests the deployment sanity (replica availability and uninterrupted service) and recovery workflows of the application pod.

Prerequisites​

  • Kubernetes >= 1.17
  • Appropriate AWS access to attach or detach an EBS volume for the instance.
  • The EBS volume should be attached to the instance.
  • The Kubernetes secret should have AWS access configuration (key) 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 = 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:AttachVolume",
                "ec2:DetachVolume"
            ],
            "Resource": "*"
        },
        {
            "Effect": "Allow",
            "Action": "ec2:DescribeVolumes",
            "Resource": "*"
        },
        {
            "Effect": "Allow",
            "Action": [
                "ec2:DescribeInstanceStatus",
                "ec2:DescribeInstances"
            ],
            "Resource": "*"
        }
    ]
}
note

Mandatory tunables​

Tunable Description Notes
EBS_VOLUME_ID Comma-separated list of volume IDs subject to EBS detach. For example, ebs-vol-1,ebs-vol-2. For more information, go to detach volumes by ID.
REGION Region name for the target volumes. 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. Default: /tmp/cloud_config.yml.
CHAOS_INTERVAL Time interval between the attachment and detachment of the volumes (in seconds). Default: 30 s. For more information, go to chaos interval.
SEQUENCE Sequence of chaos execution for multiple volumes. Default: parallel. Supports serial sequence as well. 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.

Detach volumes by ID​

Comma-separated list of volume IDs subject to EBS detach. Tune it by using the EBS_VOLUME_ID environment variable.

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

# contains EBS volume ID 
apiVersion: litmuschaos.io/v1alpha1
kind: ChaosEngine
metadata:
  name: engine-nginx
spec:
  engineState: "active"
  chaosServiceAccount: litmus-admin
  experiments:
  - name: ebs-loss-by-id
    spec:
      components:
        env:
        # ID of the EBS volume
        - name: EBS_VOLUME_ID
          value: 'ebs-vol-1'
        # region for the EBS volume
        - name: REGION
          value: 'us-east-1'
        - name: TOTAL_CHAOS_DURATION
          VALUE: '60'