Node Restart

Introduction¶

It causes chaos to disrupt state of node by restarting it.
It tests deployment sanity (replica availability & uninterrupted service) and recovery workflows of the application pod

Scenario: Restart the node

Node Restart

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 node-restart experiment resource is available in the cluster by executing kubectl get chaosexperiments in the desired namespace. If not, install from here
Create a Kubernetes secret named id-rsa where the experiment will run, where its contents will be the private SSH key for SSH_USER used to connect to the node that hosts the target pod in the secret field ssh-privatekey. A sample secret is shown below:
```
apiVersion: v1
kind: Secret
metadata:
  name: id-rsa
type: kubernetes.io/ssh-auth
stringData:
  ssh-privatekey: |-
    # SSH private key for ssh contained here
```

Creating the RSA key pair for remote SSH access should be a trivial exercise for those who are already familiar with an ssh client, which entails the following actions:

Create a new key pair and store the keys in a file named my-id-rsa-key and my-id-rsa-key.pub for the private and public keys respectively:
```
ssh-keygen -f ~/my-id-rsa-key -t rsa -b 4096
```
For each node available, run this following command to copy the public key of my-id-rsa-key:
```
ssh-copy-id -i my-id-rsa-key user@node
```

For further details, please check this documentation. Once you have copied the public key to all nodes and created the secret described earlier, you are ready to start your experiment.

Default Validations¶

View the default validations

The target nodes should be in ready state before and after chaos injection.

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: node-restart-sa
  namespace: default
  labels:
    name: node-restart-sa
    app.kubernetes.io/part-of: litmus
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  name: node-restart-sa
  labels:
    name: node-restart-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: ["configmaps","secrets"]
    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: node-restart-sa
  labels:
    name: node-restart-sa
    app.kubernetes.io/part-of: litmus
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: node-restart-sa
subjects:
- kind: ServiceAccount
  name: node-restart-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
TARGET_NODE	Name of target node, subjected to chaos. If not provided it will select the random node
NODE_LABEL	It contains node label, which will be used to filter the target node if TARGET_NODE ENV is not set	It is mutually exclusive with the TARGET_NODE ENV. If both are provided then it will use the TARGET_NODE

Optional Fields

Variables	Description	Notes
LIB_IMAGE	The image used to restart the node	Defaults to `litmuschaos/go-runner:latest`
SSH_USER	name of ssh user	Defaults to `root`
TARGET_NODE_IP	Internal IP of the target node, subjected to chaos. If not provided, the experiment will lookup the node IP of the `TARGET_NODE` node	Defaults to empty
REBOOT_COMMAND	Command used for reboot	Defaults to `sudo systemctl reboot`
TOTAL_CHAOS_DURATION	The time duration for chaos insertion (sec)	Defaults to 30s
RAMP_TIME	Period to wait before and after injection of chaos in sec
LIB	The chaos lib used to inject the chaos	Defaults to litmus supported litmus only

Experiment Examples¶

Common and Node specific tunables¶

Refer the common attributes and Node specific tunable to tune the common tunables for all experiments and node specific tunables.

Reboot Command¶

It defines the command used to restart the targeted node. It can be tuned via REBOOT_COMMAND ENV.

Use the following example to tune this:

# provide the reboot command
apiVersion: litmuschaos.io/v1alpha1
kind: ChaosEngine
metadata:
  name: engine-nginx
spec:
  engineState: "active"
  annotationCheck: "false"
  chaosServiceAccount: node-restart-sa
  experiments:
  - name: node-restart
    spec:
      components:
        env:
        # command used for the reboot
        - name: REBOOT_COMMAND
          value: 'sudo systemctl reboot'
        # name of the target node
        - name: TARGET_NODE
          value: 'node01'
        - name: TOTAL_CHAOS_DURATION
          value: '60'

SSH User¶

It defines the name of the SSH user for the targeted node. It can be tuned via SSH_USER ENV.

Use the following example to tune this:

# name of the ssh user used to ssh into targeted node
apiVersion: litmuschaos.io/v1alpha1
kind: ChaosEngine
metadata:
  name: engine-nginx
spec:
  engineState: "active"
  annotationCheck: "false"
  chaosServiceAccount: node-restart-sa
  experiments:
  - name: node-restart
    spec:
      components:
        env:
        # name of the ssh user
        - name: SSH_USER
          value: 'root'
        # name of the target node
        - name: TARGET_NODE
          value: 'node01'
        - name: TOTAL_CHAOS_DURATION
          value: '60'

Target Node Internal IP¶

It defines the internal IP of the targeted node. It is an optional field, if internal IP is not provided then it will derive the internal IP of the targeted node. It can be tuned via TARGET_NODE_IP ENV.

Use the following example to tune this:

# internal ip of the targeted node
apiVersion: litmuschaos.io/v1alpha1
kind: ChaosEngine
metadata:
  name: engine-nginx
spec:
  engineState: "active"
  annotationCheck: "false"
  chaosServiceAccount: node-restart-sa
  experiments:
  - name: node-restart
    spec:
      components:
        env:
        # internal ip of the targeted node
        - name: TARGET_NODE_IP
          value: '<ip of node01>'
        # name of the target node
        - name: TARGET_NODE
          value: 'node01'
        - name: TOTAL_CHAOS_DURATION
          value: '60'