IO Hog Scenario using Krkn-Hub
This scenario hogs the IO on the specified node on a Kubernetes/OpenShift cluster for a specified duration. For more information refer the following documentation.
Run
If enabling Cerberus to monitor the cluster and pass/fail the scenario post chaos, refer docs. Make sure to start it before injecting the chaos and set CERBERUS_ENABLED environment variable for the chaos injection container to autoconnect.
$ podman run --name=<container_name> --net=host --env-host=true -v <path-to-kube-config>:/root/.kube/config:Z -d quay.io/krkn-chaos/krkn-hub:node-io-hog
$ podman logs -f <container_name or container_id> # Streams Kraken logs
$ podman inspect <container-name or container-id> --format "{{.State.ExitCode}}" # Outputs exit code which can considered as pass/fail for the scenario
$ docker run $(./get_docker_params.sh) --name=<container_name> --net=host -v <path-to-kube-config>:/root/.kube/config:Z -d quay.io/krkn-chaos/krkn-hub:node-io-hog
OR
$ docker run -e <VARIABLE>=<value> --net=host -v <path-to-kube-config>:/root/.kube/config:Z -d quay.io/krkn-chaos/krkn-hub:node-io-hog
$ docker logs -f <container_name or container_id> # Streams Kraken logs
$ docker inspect <container-name or container-id> --format "{{.State.ExitCode}}" # Outputs exit code which can considered as pass/fail for the scenario
Tip
Because the container runs with a non-root user, ensure the kube config is globally readable before mounting it in the container. You can achieve this with the following commands:kubectl config view --flatten > ~/kubeconfig && chmod 444 ~/kubeconfig && docker run $(./get_docker_params.sh) --name=<container_name> --net=host -v ~kubeconfig:/home/krkn/.kube/config:Z -d quay.io/krkn-chaos/krkn-hub:<scenario>Supported parameters
The following environment variables can be set on the host running the container to tweak the scenario/faults being injected:
example:
export <parameter_name>=<value>
See list of variables that apply to all scenarios here that can be used/set in addition to these scenario specific variables
| Parameter | Description | Default |
|---|---|---|
| TOTAL_CHAOS_DURATION | Set chaos duration (in sec) as desired | 180 |
| IO_BLOCK_SIZE | string size of each write in bytes. Size can be from 1 byte to 4m | 1m |
| IO_WORKERS | Number of stressorts | 5 |
| IO_WRITE_BYTES | string writes N bytes for each hdd process. The size can be expressed as % of free space on the file system or in units of Bytes, KBytes, MBytes and GBytes using the suffix b, k, m or g | 10m |
| NAMESPACE | Namespace where the scenario container will be deployed | default |
| NODE_SELECTORS | Node selectors where the scenario containers will be scheduled in the format “<selector>=<value>”. NOTE: This value can be specified as a list of node selectors separated by “;”. Will be instantiated a container per each node selector with the same scenario options. This option is meant to run one or more stress scenarios simultaneously on different nodes, kubernetes will schedule the pods on the target node accordingly with the selector specified. Specifying the same selector multiple times will instantiate as many scenario container as the number of times the selector is specified on the same node | "" |
Note
In case of using custom metrics profile or alerts profile whenCAPTURE_METRICS or ENABLE_ALERTS is enabled, mount the metrics profile from the host on which the container is run using podman/docker under /home/krkn/kraken/config/metrics-aggregated.yaml and /home/krkn/kraken/config/alerts.$ podman run --name=<container_name> --net=host --env-host=true -v <path-to-custom-metrics-profile>:/root/kraken/config/metrics-aggregated.yaml -v <path-to-custom-alerts-profile>:/root/kraken/config/alerts -v <path-to-kube-config>:/root/.kube/config:Z -d quay.io/krkn-chaos/krkn-hub:node-io-hog