EC2 Stop By Tag

Introduction¶

It causes stopping of an EC2 instance by tag before bringing it back to running state after the specified chaos duration.
It helps to check the performance of the application/process running on the ec2 instance. When the MANAGED_NODEGROUP is enable then the experiment will not try to start the instance post chaos instead it will check of the addition of the new node instance to the cluster.

Scenario: Stop EC2 Instance

EC2 Stop 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 ec2-stop-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 stop and start an ec2 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.

WARNING¶

If the target EC2 instance is a part of a self-managed nodegroup: Make sure to drain the target node if any application is running on it and also ensure to cordon the target node before running the experiment so that the experiment pods do not schedule on it.

Default Validations¶

View the default validations

EC2 instance should be in healthy state.

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: ec2-stop-by-tag-sa
  namespace: default
  labels:
    name: ec2-stop-by-tag-sa
    app.kubernetes.io/part-of: litmus
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  name: ec2-stop-by-tag-sa
  labels:
    name: ec2-stop-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"]
  # for experiment to perform node status checks
  - apiGroups: [""]
    resources: ["nodes"]
    verbs: ["get","list"]
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name: ec2-stop-by-tag-sa
  labels:
    name: ec2-stop-by-tag-sa
    app.kubernetes.io/part-of: litmus
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: ec2-stop-by-tag-sa
subjects:
- kind: ServiceAccount
  name: ec2-stop-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
INSTANCE_TAG	Instance Tag to filter the target ec2 instance.	The `INSTANCE_TAG` should be provided as `key:value` ex: `team:devops`
REGION	The region name of the target instace

Optional Fields

Variables	Description	Notes
INSTANCE_AFFECTED_PERC	The Percentage of total ec2 instance to target	Defaults to 0 (corresponds to 1 instance), provide numeric value only
TOTAL_CHAOS_DURATION	The total time duration for chaos insertion (sec)	Defaults to 30s
CHAOS_INTERVAL	The interval (in sec) between successive instance termination.	Defaults to 30s
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	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 instance¶

It will stop a random single ec2 instance with the given INSTANCE_TAG tag and the REGION region.

Use the following example to tune this:

# target the ec2 instances with matching tag
apiVersion: litmuschaos.io/v1alpha1
kind: ChaosEngine
metadata:
  name: engine-nginx
spec:
  engineState: "active"
  annotationCheck: "false"
  chaosServiceAccount: ec2-terminate-by-tag-sa
  experiments:
  - name: ec2-stop-by-tag
    spec:
      components:
        env:
        # tag of the ec2 instance
        - name: INSTANCE_TAG
          value: 'key:value'
        # region for the ec2 instance
        - name: REGION
          value: '<region for instance>'
        - name: TOTAL_CHAOS_DURATION
          value: '60'

Target Percent of instances¶

It will stop the INSTANCE_AFFECTED_PERC percentage of ec2 instances with the given INSTANCE_TAG tag and REGION region.

Use the following example to tune this:

# percentage of ec2 instances, needs to terminate with provided tags
apiVersion: litmuschaos.io/v1alpha1
kind: ChaosEngine
metadata:
  name: engine-nginx
spec:
  engineState: "active"
  annotationCheck: "false"
  chaosServiceAccount: ec2-stop-by-tag-sa
  experiments:
  - name: ec2-stop-by-tag
    spec:
      components:
        env:
        # percentage of ec2 instance filterd by tags 
        - name: INSTANCE_AFFECTED_PERC
          value: '100'
        # tag of the ec2 instance
        - name: INSTANCE_TAG
          value: 'key:value'
        # region for the ec2 instance
        - name: REGION
          value: '<region for instance>'
        - name: TOTAL_CHAOS_DURATION
          value: '60'