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Getting Started Running Chaos Scenarios

Adding New Scenarios

Adding a new scenario is as simple as adding a new config file under scenarios directory and defining it in the main kraken config. You can either copy an existing yaml file and make it your own, or fill in one of the templates below to suit your needs.

Templates

Pod Scenario Yaml Template

For example, for adding a pod level scenario for a new application, refer to the sample scenario below to know what fields are necessary and what to add in each location:

config:
  runStrategy:
    runs: <number of times to execute the scenario>
    #This will choose a random number to wait between min and max
    maxSecondsBetweenRuns: 30
    minSecondsBetweenRuns: 1
scenarios:
  - name: "delete pods example"
    steps:
    - podAction:
        matches:
          - labels:
              namespace: "<namespace>"
              selector: "<pod label>"  # This can be left blank.
        filters:
          - randomSample:
              size: <number of pods to kill>
        actions:
          - kill:
              probability: 1
              force: true
    - podAction:
        matches:
          - labels:
              namespace: "<namespace>"
              selector: "<pod label>"  # This can be left blank.
        retries:
          retriesTimeout:
            # Amount of time to wait with retrying, before failing if pod count does not match expected
            # timeout: 180.

        actions:
          - checkPodCount:
              count: <expected number of pods that match namespace and label"

More information on specific items that you can add to the pod killing scenarios can be found in the powerfulseal policies documentation

Node Scenario Yaml Template

node_scenarios:
  - actions:  # Node chaos scenarios to be injected.
    - <chaos scenario>
    - <chaos scenario>
    node_name: <node name>  # Can be left blank.
    label_selector: <node label>
    instance_kill_count: <number of nodes on which to perform action>
    timeout: <duration to wait for completion>
    cloud_type: <cloud provider>

Time Chaos Scenario Template

time_scenarios:
  - action: 'skew_time' or 'skew_date'
    object_type: 'pod' or 'node'
    label_selector: <label of pod or node>

Common Scenario Edits

If you just want to make small changes to pre-existing scenarios, feel free to edit the scenario file itself.

Example of Quick Pod Scenario Edit:

If you want to kill 2 pods instead of 1 in any of the pre-existing scenarios, you can either edit the number located at filters -> randomSample -> size or the runs under the config -> runStrategy section.

Example of Quick Nodes Scenario Edit:

If your cluster is build on GCP instead of AWS, just change the cloud type in the node_scenarios_example.yml file.