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Node Scenarios

The following node chaos scenarios are supported:

  1. node_start_scenario: Scenario to stop the node instance.
  2. node_stop_scenario: Scenario to stop the node instance.
  3. node_stop_start_scenario: Scenario to stop and then start the node instance. Not supported on VMware.
  4. node_termination_scenario: Scenario to terminate the node instance.
  5. node_reboot_scenario: Scenario to reboot the node instance.
  6. stop_kubelet_scenario: Scenario to stop the kubelet of the node instance.
  7. stop_start_kubelet_scenario: Scenario to stop and start the kubelet of the node instance.
  8. node_crash_scenario: Scenario to crash the node instance.
  9. stop_start_helper_node_scenario: Scenario to stop and start the helper node and check service status.

NOTE: If the node does not recover from the node_crash_scenario injection, reboot the node to get it back to Ready state.

NOTE: node_start_scenario, node_stop_scenario, node_stop_start_scenario, node_termination_scenario , node_reboot_scenario and stop_start_kubelet_scenario are supported only on AWS, Azure, OpenStack, BareMetal, GCP , VMware and Alibaba as of now.

NOTE: Node scenarios are supported only when running the standalone version of Kraken until #106 gets fixed.

AWS

How to set up AWS cli to run node scenarios is defined here.

Baremetal

NOTE: Baremetal requires setting the IPMI user and password to power on, off, and reboot nodes, using the config options bm_user and bm_password. It can either be set in the root of the entry in the scenarios config, or it can be set per machine.

If no per-machine addresses are specified, kraken attempts to use the BMC value in the BareMetalHost object. To list them, you can do 'oc get bmh -o wide --all-namespaces'. If the BMC values are blank, you must specify them per-machine using the config option 'bmc_addr' as specified below.

For per-machine settings, add a "bmc_info" section to the entry in the scenarios config. Inside there, add a configuration section using the node name. In that, add per-machine settings. Valid settings are 'bmc_user', 'bmc_password', and 'bmc_addr'. See the example node scenario or the example below.

NOTE: Baremetal requires oc (openshift client) be installed on the machine running Kraken.

NOTE: Baremetal machines are fragile. Some node actions can occasionally corrupt the filesystem if it does not shut down properly, and sometimes the kubelet does not start properly.

Docker

The Docker provider can be used to run node scenarios against kind clusters.

kind is a tool for running local Kubernetes clusters using Docker container "nodes".

kind was primarily designed for testing Kubernetes itself, but may be used for local development or CI.

GCP

How to set up GCP cli to run node scenarios is defined here.

Openstack

How to set up Openstack cli to run node scenarios is defined here.

The supported node level chaos scenarios on an OPENSTACK cloud are node_stop_start_scenario, stop_start_kubelet_scenario and node_reboot_scenario.

NOTE: For stop_start_helper_node_scenario, visit here to learn more about the helper node and its usage.

To execute the scenario, ensure the value for ssh_private_key in the node scenarios config file is set with the correct private key file path for ssh connection to the helper node. Ensure passwordless ssh is configured on the host running Kraken and the helper node to avoid connection errors.

Azure

How to set up Azure cli to run node scenarios is defined here.

Alibaba

How to set up Alibaba cli to run node scenarios is defined here.

NOTE: There is no "terminating" idea in Alibaba, so any scenario with terminating will "release" the node . Releasing a node is 2 steps, stopping the node and then releasing it.

VMware

How to set up VMware vSphere to run node scenarios is defined here

This cloud type uses a different configuration style, see actions below and example config file

vmware-node-terminate, vmware-node-reboot, vmware-node-stop, vmware-node-start

IBMCloud

How to set up IBMCloud to run node scenarios is defined here

This cloud type uses a different configuration style, see actions below and example config file

*ibmcloud-node-terminate, ibmcloud-node-reboot, ibmcloud-node-stop, ibmcloud-node-start *

IBMCloud and Vmware example

- id: ibmcloud-node-stop
  config:
    name: "<node_name>"        
    label_selector: "node-role.kubernetes.io/worker"    # When node_name is not specified, a node with matching label_selector is selected for node chaos scenario injection 
    runs: 1                             # Number of times to inject each scenario under actions (will perform on same node each time)                                                           
    instance_count: 1                   # Number of nodes to perform action/select that match the label selector                                             
    timeout: 30                        # Duration to wait for completion of node scenario injection
    skip_openshift_checks: False       # Set to True if you don't want to wait for the status of the nodes to change on OpenShift before passing the scenario 
- id: ibmcloud-node-start
  config:
    name: "<node_name>" #Same name as before       
    label_selector: "node-role.kubernetes.io/worker"    # When node_name is not specified, a node with matching label_selector is selected for node chaos scenario injection 
    runs: 1                             # Number of times to inject each scenario under actions (will perform on same node each time)                                                           
    instance_count: 1                   # Number of nodes to perform action/select that match the label selector                                             
    timeout: 30                        # Duration to wait for completion of node scenario injection
    skip_openshift_checks: False       # Set to True if you don't want to wait for the status of the nodes to change on OpenShift before passing the scenario 
    ```



#### General

**NOTE**: The `node_crash_scenario` and `stop_kubelet_scenario` scenario is supported independent of the cloud platform.

Use 'generic' or do not add the 'cloud_type' key to your scenario if your cluster is not set up using one of the current supported cloud types.

Node scenarios can be injected by placing the node scenarios config files under node_scenarios option in the kraken config. Refer to [node_scenarios_example](https://github.com/redhat-chaos/krkn/blob/main/scenarios/node_scenarios_example.yml) config file.

node_scenarios:

  • actions: # Node chaos scenarios to be injected.
    • node_stop_start_scenario
    • stop_start_kubelet_scenario
    • node_crash_scenario node_name: # Node on which scenario has to be injected. label_selector: node-role.kubernetes.io/worker # When node_name is not specified, a node with matching label_selector is selected for node chaos scenario injection. instance_count: 1 # Number of nodes to perform action/select that match the label selector. runs: 1 # Number of times to inject each scenario under actions (will perform on same node each time). timeout: 120 # Duration to wait for completion of node scenario injection. cloud_type: aws # Cloud type on which Kubernetes/OpenShift runs.
  • actions:
    • node_reboot_scenario node_name: label_selector: node-role.kubernetes.io/infra instance_count: 1 timeout: 120 cloud_type: azure
  • actions:
    • node_crash_scenario node_name: label_selector: node-role.kubernetes.io/infra instance_count: 1 timeout: 120
  • actions:
    • stop_start_helper_node_scenario # Node chaos scenario for helper node. instance_count: 1 timeout: 120 helper_node_ip: # ip address of the helper node. service: # Check status of the services on the helper node.
      • haproxy
      • dhcpd
      • named ssh_private_key: /root/.ssh/id_rsa # ssh key to access the helper node. cloud_type: openstack
  • actions:
    • node_stop_start_scenario node_name: label_selector: node-role.kubernetes.io/worker instance_count: 1 timeout: 120 cloud_type: bm bmc_user: defaultuser # For baremetal (bm) cloud type. The default IPMI username. Optional if specified for all machines. bmc_password: defaultpass # For baremetal (bm) cloud type. The default IPMI password. Optional if specified for all machines. bmc_info: # This section is here to specify baremetal per-machine info, so it is optional if there is no per-machine info. node-1: # The node name for the baremetal machine bmc_addr: mgmt-machine1.example.com # Optional. For baremetal nodes with the IPMI BMC address missing from 'oc get bmh'. node-2: bmc_addr: mgmt-machine2.example.com bmc_user: user # The baremetal IPMI user. Overrides the default IPMI user specified above. Optional if the default is set. bmc_password: pass # The baremetal IPMI password. Overrides the default IPMI user specified above. Optional if the default is set.