EBS loss by ID

Introduction

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.

Use cases

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

note

• Kubernetes version 1.17 or later is required to execute this fault.
• 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
• We recommend 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 and you won't be able to use the default health check probes.
• Refer to AWS named profile for chaos to use a different profile for AWS faults and superset permission or policy to execute all AWS faults.
• Go to the common tunables and AWS-specific tunables to tune the common tunables for all faults and AWS-specific tunables.

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": "*"
        }
    ]
}

Fault tunables

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.
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.
CHAOS_INTERVAL	Time interval between the attachment and detachment of the volumes (in seconds).	Default: 30 s.
SEQUENCE	Sequence of chaos execution for multiple volumes.	Default: parallel. Supports serial sequence as well.
RAMP_TIME	Period to wait before and after injecting chaos (in seconds).	For example, 30 s.

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'