EBS Loss By Tag

Introduction¶

It causes chaos to disrupt state of ebs volume by detaching it from the node/ec2 instance for a certain chaos duration using volume tags.
In case of EBS persistent volumes, the volumes can get self-attached and experiment skips the re-attachment step. Tests deployment sanity (replica availability & uninterrupted service) and recovery workflows of the application pod.

Scenario: Detach EBS Volume

EBS Loss By Tag

Uses¶

View the uses of the experiment

coming soon

Prerequisites¶

Verify the prerequisites

Ensure that Kubernetes Version > 1.16
Ensure that the Litmus Chaos Operator is running by executing kubectl get pods in operator namespace (typically, litmus).If not, install from here
Ensure that the ebs-loss-by-tag experiment resource is available in the cluster by executing kubectl get chaosexperiments in the desired namespace. If not, install from here
Ensure that you have sufficient AWS access to attach or detach an ebs volume for the instance.

Ensure to create a Kubernetes secret having 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

If you change the secret key name (from cloud_config.yml) please also update the AWS_SHARED_CREDENTIALS_FILE ENV value on experiment.yamlwith the same name.

Default Validations¶

View the default validations

EBS volume is attached to the instance.

Minimal RBAC configuration example (optional)¶

NOTE

If you are using this experiment as part of a litmus workflow scheduled constructed & executed from chaos-center, then you may be making use of the litmus-admin RBAC, which is pre installed in the cluster as part of the agent setup.

View the Minimal RBAC permissions

---
apiVersion: v1
kind: ServiceAccount
metadata:
  name: ebs-loss-by-tag-sa
  namespace: default
  labels:
    name: ebs-loss-by-tag-sa
    app.kubernetes.io/part-of: litmus
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  name: ebs-loss-by-tag-sa
  labels:
    name: ebs-loss-by-tag-sa
    app.kubernetes.io/part-of: litmus
rules:
  # Create and monitor the experiment & helper pods
  - apiGroups: [""]
    resources: ["pods"]
    verbs: ["create","delete","get","list","patch","update", "deletecollection"]
  # Performs CRUD operations on the events inside chaosengine and chaosresult
  - apiGroups: [""]
    resources: ["events"]
    verbs: ["create","get","list","patch","update"]
  # Fetch configmaps & secrets details and mount it to the experiment pod (if specified)
  - apiGroups: [""]
    resources: ["secrets","configmaps"]
    verbs: ["get","list",]
  # Track and get the runner, experiment, and helper pods log 
  - apiGroups: [""]
    resources: ["pods/log"]
    verbs: ["get","list","watch"]  
  # for creating and managing to execute comands inside target container
  - apiGroups: [""]
    resources: ["pods/exec"]
    verbs: ["get","list","create"]
  # for configuring and monitor the experiment job by the chaos-runner pod
  - apiGroups: ["batch"]
    resources: ["jobs"]
    verbs: ["create","list","get","delete","deletecollection"]
  # for creation, status polling and deletion of litmus chaos resources used within a chaos workflow
  - apiGroups: ["litmuschaos.io"]
    resources: ["chaosengines","chaosexperiments","chaosresults"]
    verbs: ["create","list","get","patch","update","delete"]
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name: ebs-loss-by-tag-sa
  labels:
    name: ebs-loss-by-tag-sa
    app.kubernetes.io/part-of: litmus
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: ebs-loss-by-tag-sa
subjects:
- kind: ServiceAccount
  name: ebs-loss-by-tag-sa
  namespace: default

Use this sample RBAC manifest to create a chaosServiceAccount in the desired (app) namespace. This example consists of the minimum necessary role permissions to execute the experiment.

Experiment tunables¶

check the experiment 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

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

Experiment Examples¶

Common and AWS specific tunables¶

Refer the common attributes and AWS specific tunable to tune the common tunables for all experiments 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"
  annotationCheck: "false"
  chaosServiceAccount: ebs-loss-by-tag-sa
  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: '<region for EBS_VOLUME_TAG>'
        - 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 this:

# target percentage of the ebs volumes with the provided tag
apiVersion: litmuschaos.io/v1alpha1
kind: ChaosEngine
metadata:
  name: engine-nginx
spec:
  engineState: "active"
  annotationCheck: "false"
  chaosServiceAccount: ebs-loss-by-tag-sa
  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: '<region for EBS_VOLUME_TAG>'
        - name: TOTAL_CHAOS_DURATION
          value: '60'