To enable this plugin add the pointer to the scenario input file scenarios/kube/memory-hog.yml as described in the
Usage section.
Example scenario file: memory-hog.yml
memory-hog options
In addition to the common hog scenario options, you can specify the below options in your scenario configuration to specificy the amount of memory to hog on a certain worker node
| Option |
Type |
Description |
memory-vm-bytes |
string |
the amount of memory that the scenario will try to hog.The size can be specified 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 |
Usage
To enable hog scenarios edit the kraken config file, go to the section kraken -> chaos_scenarios of the yaml structure
and add a new element to the list named hog_scenarios then add the desired scenario
pointing to the hog.yaml file.
kraken:
...
chaos_scenarios:
- hog_scenarios:
- scenarios/kube/memory-hog.yml
Note
You can specify multiple scenario files of the same type by adding additional paths to the list:
kraken:
chaos_scenarios:
- hog_scenarios:
- scenarios/kube/memory-hog-1.yml
- scenarios/kube/memory-hog-2.yml
- scenarios/kube/memory-hog-3.yml
You can also combine multiple different scenario types in the same config.yaml file. Scenario types can be specified in any order, and you can include the same scenario type multiple times:
kraken:
chaos_scenarios:
- hog_scenarios:
- scenarios/kube/memory-hog.yml
- pod_disruption_scenarios:
- scenarios/pod-kill.yaml
- node_scenarios:
- scenarios/node-reboot.yaml
- hog_scenarios: # Same type can appear multiple times
- scenarios/kube/memory-hog-2.yml
Run
python run_kraken.py --config config/config.yaml
This scenario hogs the memory 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 \
--pull=always \
--env-host=true \
-v <path-to-kube-config>:/home/krkn/.kube/config:Z \
-d containers.krkn-chaos.dev/krkn-chaos/krkn-hub:node-memory-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
Note
–env-host: This option is not available with the remote Podman client, including Mac and Windows (excluding WSL2) machines.
Without the –env-host option you’ll have to set each environment variable on the podman command line like -e <VARIABLE>=<value>
$ docker run $(./get_docker_params.sh) \
--name=<container_name> \
--net=host \
--pull=always \
-v <path-to-kube-config>:/home/krkn/.kube/config:Z \
-d containers.krkn-chaos.dev/krkn-chaos/krkn-hub:node-memory-hog
$ docker run \
-e <VARIABLE>=<value> \
--net=host \
--pull=always \
-v <path-to-kube-config>:/home/krkn/.kube/config:Z \
-d containers.krkn-chaos.dev/krkn-chaos/krkn-hub:node-memory-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 --pull=always -v ~/kubeconfig:/home/krkn/.kube/config:Z -d containers.krkn-chaos.dev/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 if –env-host is used:
export <parameter_name>=<value>
OR on the command line like example:
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 |
60 |
| MEMORY_CONSUMPTION_PERCENTAGE |
percentage (expressed with the suffix %) or amount (expressed with the suffix b, k, m or g) of memory to be consumed by the scenario |
90% |
| NUMBER_OF_WORKERS |
Total number of workers (stress-ng threads) |
1 |
| NAMESPACE |
Namespace where the scenario container will be deployed |
default |
| NODE_SELECTOR |
defines the node selector for choosing target nodes. If not specified, one schedulable node in the cluster will be chosen at random. If multiple nodes match the selector, all of them will be subjected to stress. If number-of-nodes is specified, that many nodes will be randomly selected from those identified by the selector. |
"" |
| TAINTS |
List of taints for which tolerations need to be created. Example: [“node-role.kubernetes.io/master:NoSchedule”] |
[] |
| NUMBER_OF_NODES |
restricts the number of selected nodes by the selector |
"" |
| IMAGE |
the container image of the stress workload |
quay.io/krkn-chaos/krkn-hog |
Note
In case of using custom metrics profile or alerts profile when CAPTURE_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.
For example:
$ podman run \
--name=<container_name> \
--net=host \
--pull=always \
--env-host=true \
-v <path-to-custom-metrics-profile>:/home/krkn/kraken/config/metrics-aggregated.yaml \
-v <path-to-custom-alerts-profile>:/home/krkn/kraken/config/alerts \
-v <path-to-kube-config>:/home/krkn/.kube/config:Z \
-d containers.krkn-chaos.dev/krkn-chaos/krkn-hub:node-memory-hog
krknctl run node-memory-hog [--<parameter> <value>]
Can also set any global variable listed here
| Parameter |
Description |
Type |
Required |
Default |
--chaos-duration |
Set chaos duration (in sec) as desired |
number |
No |
60 |
--memory-workers |
Total number of workers (stress-ng threads) |
number |
No |
1 |
--memory-consumption |
percentage (expressed with the suffix %) or amount (expressed with the suffix b, k, m or g) of memory to be consumed by the scenario |
string |
No |
90% |
--namespace |
Namespace where the scenario container will be deployed |
string |
No |
default |
--node-selector |
Node selector where the scenario containers will be scheduled in the format “=”. NOTE: Will be instantiated a container per each node selected with the same scenario options. If left empty a random node will be selected |
string |
No |
|
--taints |
List of taints for which tolerations need to be created. For example [“node-role.kubernetes.io/master:NoSchedule”]" |
string |
No |
[] |
--number-of-nodes |
restricts the number of selected nodes by the selector |
number |
No |
|
--image |
The hog container image. Can be changed if the hog image is mirrored on a private repository |
string |
No |
quay.io/krkn-chaos/krkn-hog |
To see all available scenario options
krknctl run node-memory-hog --help