## Introduction
- It causes power-off of a GCP VM instance by instance name or list of instance names before bringing it back to the running state after the specified chaos duration.
- It helps to check the performance of the application/process running on the VM instance.
- When the `AUTO_SCALING_GROUP` is enable then the experiment will not try to start the instance post chaos, instead it will check the addition of the new node instances to the cluster.
!!! tip "Scenario: stop the gcp vm"

## Uses
??? info "View the uses of the experiment"
coming soon
## Prerequisites
??? info "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 gcp-vm-instance-stop
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 GCP permissions to stop and start the GCP VM instances.
- Ensure to create a Kubernetes secret having the GCP service account credentials in the default namespace. A sample secret file looks like:
```yaml
apiVersion: v1
kind: Secret
metadata:
name: cloud-secret
type: Opaque
stringData:
type:
project_id:
private_key_id:
private_key:
client_email:
client_id:
auth_uri:
token_uri:
auth_provider_x509_cert_url:
client_x509_cert_url:
```
## Default Validations
??? info "View the default validations"
- VM instance should be in healthy state.
## Minimal RBAC configuration example (optional)
!!! tip "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](https://litmuschaos.github.io/litmus/litmus-admin-rbac.yaml) RBAC, which is pre installed in the cluster as part of the agent setup.
??? note "View the Minimal RBAC permissions"
[embedmd]:# (https://raw.githubusercontent.com/litmuschaos/chaos-charts/master/charts/gcp/gcp-vm-instance-stop/rbac.yaml yaml)
```yaml
---
apiVersion: v1
kind: ServiceAccount
metadata:
name: gcp-vm-instance-stop-sa
namespace: default
labels:
name: gcp-vm-instance-stop-sa
app.kubernetes.io/part-of: litmus
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
name: gcp-vm-instance-stop-sa
labels:
name: gcp-vm-instance-stop-sa
app.kubernetes.io/part-of: litmus
rules:
- apiGroups: [""]
resources: ["pods","events","secrets"]
verbs: ["create","list","get","patch","update","delete","deletecollection"]
- apiGroups: [""]
resources: ["pods/exec","pods/log"]
verbs: ["create","list","get"]
- apiGroups: ["batch"]
resources: ["jobs"]
verbs: ["create","list","get","delete","deletecollection"]
- apiGroups: ["litmuschaos.io"]
resources: ["chaosengines","chaosexperiments","chaosresults"]
verbs: ["create","list","get","patch","update"]
- apiGroups: [""]
resources: ["nodes"]
verbs: ["get","list"]
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
name: gcp-vm-instance-stop-sa
labels:
name: gcp-vm-instance-stop-sa
app.kubernetes.io/part-of: litmus
roleRef:
apiGroup: rbac.authorization.k8s.io
kind: ClusterRole
name: gcp-vm-instance-stop-sa
subjects:
- kind: ServiceAccount
name: gcp-vm-instance-stop-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
??? info "check the experiment tunables"
Mandatory Fields
Variables |
Description |
Notes |
GCP_PROJECT_ID |
GCP project ID to which the VM instances belong |
All the VM instances must belong to a single GCP project |
VM_INSTANCE_NAMES |
Name of target VM instances |
Multiple instance names can be provided as instance1,instance2,... |
INSTANCE_ZONES |
The zones of the target VM instances |
Zone for every instance name has to be provided as zone1,zone2,... in the same order of VM_INSTANCE_NAMES |
Optional Fields
Variables |
Description |
Notes |
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 |
AUTO_SCALING_GROUP |
Set to enable if the target instance is the part of a auto-scaling group |
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 Experiment Tunables
Refer the [common attributes](../common/common-tunables-for-all-experiments.md) to tune the common tunables for all the experiments.
### Target GCP Instances
It will stop all the instances with the given `VM_INSTANCE_NAMES` instance names and corresponding `INSTANCE_ZONES` zone names in `GCP_PROJECT_ID` project.
`NOTE:` The `VM_INSTANCE_NAMES` contains multiple comma-separated vm instances. The comma-separated zone names should be provided in the same order as instance names.
Use the following example to tune this:
[embedmd]:# (https://raw.githubusercontent.com/litmuschaos/litmus/master/mkdocs/docs/experiments/categories/gcp/gcp-vm-instance-stop/gcp-instance.yaml yaml)
```yaml
## details of the gcp instance
apiVersion: litmuschaos.io/v1alpha1
kind: ChaosEngine
metadata:
name: engine-nginx
spec:
engineState: "active"
annotationCheck: "false"
chaosServiceAccount: gcp-vm-instance-stop-sa
experiments:
- name: gcp-vm-instance-stop
spec:
components:
env:
# comma separated list of vm instance names
- name: VM_INSTANCE_NAMES
value: 'instance-01,instance-02'
# comma separated list of zone names corresponds to the VM_INSTANCE_NAMES
# it should be provided in same order of VM_INSTANCE_NAMES
- name: INSTANCE_ZONES
value: 'zone-01,zone-02'
# gcp project id to which vm instance belongs
- name: GCP_PROJECT_ID
value: 'project-id'
- name: TOTAL_CHAOS_DURATION
VALUE: '60'
```
### Autoscaling NodeGroup
If vm instances belong to the autoscaling group then provide the `AUTO_SCALING_GROUP` as `enable` else provided it as `disable`. The default value of `AUTO_SCALING_GROUP` is `disable`.
Use the following example to tune this:
[embedmd]:# (https://raw.githubusercontent.com/litmuschaos/litmus/master/mkdocs/docs/experiments/categories/gcp/gcp-vm-instance-stop/auto-scaling.yaml yaml)
```yaml
## scale up and down to maintain the available instance counts
apiVersion: litmuschaos.io/v1alpha1
kind: ChaosEngine
metadata:
name: engine-nginx
spec:
engineState: "active"
annotationCheck: "false"
chaosServiceAccount: gcp-vm-instance-stop-sa
experiments:
- name: gcp-vm-instance-stop
spec:
components:
env:
# tells if instances are part of autoscaling group
# supports: enable, disable. default: disable
- name: AUTO_SCALING_GROUP
value: 'enable'
# comma separated list of vm instance names
- name: VM_INSTANCE_NAMES
value: 'instance-01,instance-02'
# comma separated list of zone names corresponds to the VM_INSTANCE_NAMES
# it should be provided in same order of VM_INSTANCE_NAMES
- name: INSTANCE_ZONES
value: 'zone-01,zone-02'
# gcp project id to which vm instance belongs
- name: GCP_PROJECT_ID
value: 'project-id'
- name: TOTAL_CHAOS_DURATION
VALUE: '60'
```
### Mutiple Iterations Of Chaos
The multiple iterations of chaos can be tuned via setting `CHAOS_INTERVAL` ENV. Which defines the delay between each iteration of chaos.
Use the following example to tune this:
[embedmd]:# (https://raw.githubusercontent.com/litmuschaos/litmus/master/mkdocs/docs/experiments/categories/gcp/gcp-vm-instance-stop/chaos-interval.yaml yaml)
```yaml
# defines delay between each successive iteration of the chaos
apiVersion: litmuschaos.io/v1alpha1
kind: ChaosEngine
metadata:
name: engine-nginx
spec:
engineState: "active"
annotationCheck: "false"
chaosServiceAccount: gcp-vm-instance-stop-sa
experiments:
- name: gcp-vm-instance-stop
spec:
components:
env:
# delay between each iteration of chaos
- name: CHAOS_INTERVAL
value: '15'
# time duration for the chaos execution
- name: TOTAL_CHAOS_DURATION
VALUE: '60'
- name: VM_INSTANCE_NAMES
value: 'instance-01,instance-02'
- name: INSTANCE_ZONES
value: 'zone-01,zone-02'
- name: GCP_PROJECT_ID
value: 'project-id'
```