EBS loss by tag

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

Usage

View fault usage

It tests the deployment sanity (replica availability and uninterrupted service) and recovery workflows of the application pod.

Prerequisites

• Kubernetes > 1.16.
• Adequate AWS access to attach or detach an EBS volume for the instance.
• Create a Kubernetes secret that has the AWS access configuration(key) in the CHAOS_NAMESPACE. A sample secret file looks like:

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

• It is recommended to use the same secret name, i.e. cloud-secret. Otherwise, you will need to update the AWS_SHARED_CREDENTIALS_FILE environment variable in the fault template and you may be unable to use the default health check probes.

• Refer to AWS Named Profile For Chaos to know how to use a different profile for AWS faults.

Permissions required

Here is an example AWS policy to execute the fault.

View policy for 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": "*"
        }
    ]
}

Refer to the superset permission/policy to execute all AWS faults.

Default validations

EBS volume is attached to the instance.

Fault tunables

Fault tunables

Mandatory fields

Variables	Description	Notes
EBS_VOLUME_TAG	Provide the common tag for target volumes. It'll be in form of key:value (Ex: 'team:devops')
REGION	The region name for the target volumes	For example, us-east-1.

Optional fields

Variables	Description	Notes
VOLUME_AFFECTED_PERC	The Percentage of total EBS volumes to target	Defaults to 0 (corresponds to 1 volume), provide numeric value only
TOTAL_CHAOS_DURATION	The time duration for chaos insertion (sec)	Defaults to 30s
CHAOS_INTERVAL	The time duration between the attachment and detachment of the volumes (sec)	Defaults to 30s
SEQUENCE	It defines sequence of chaos execution for multiple volumes	Default value: parallel. Supported: serial, parallel
RAMP_TIME	Period to wait before and after injection of chaos in sec	For example, 30

Fault examples

Common and AWS-specific tunables

Refer to the common attributes and AWS-specific tunables to tune the common tunables for all faults and aws specific tunables.

Target single volume

It will detach a random single EBS volume with the given EBS_VOLUME_TAG tag and REGION region.

Use the following example to tune this:

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

Target percent of volumes

It will detach the VOLUME_AFFECTED_PERC percentage of EBS volumes with the given EBS_VOLUME_TAG tag and REGION region.

Use the following example to tune it:

# target percentage of the EBS volumes with the provided tag
apiVersion: litmuschaos.io/v1alpha1
kind: ChaosEngine
metadata:
  name: engine-nginx
spec:
  engineState: "active"
  chaosServiceAccount: litmus-admin
  experiments:
  - name: ebs-loss-by-tag
    spec:
      components:
        env:
        # percentage of EBS volumes filter by tag
        - name: VOLUME_AFFECTED_PERC
          value: '100'
        # tag of the EBS volume
        - name: EBS_VOLUME_TAG
          value: 'key:value'
        # region for the EBS volume
        - name: REGION
          value: 'us-east-1'
        - name: TOTAL_CHAOS_DURATION
          VALUE: '60'