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Pod IO attribute override

Pod IO Attribute Override, modify the properties of files located within the mounted volume of the pod. This fault should be used as a sanity test for validating your application's failover capability against unexpected changes in file attributes, such as permissions, ownership, or timestamps.

Pod IO Attribute Override

Use cases

Pod IO attribute override:

  • Tests whether your application is able to detect and respond to unexpected changes in file attributes, which can help you ensure that your system remains compliant and secure.
  • Tests whether your disaster recovery system is able to restore files and maintain file attributes correctly.
  • Tests whether your backup system is able to restore files and maintain file attributes correctly.
  • Tests whether your change management process is able to detect and respond to unexpected changes in file attributes, which can help you ensure that your system remains stable and secure.
caution
  • Due to the large blast radius of this fault, we recommend you do not execute it in the production environment.
  • Through the fault execution, the application pod can potentially fail to perform successful IO writes if the write system call is being targeted. This can cause any data produced in this duration to be lost.
  • Any data produced before the execution of the fault is not harmed as a result of its execution.
note
  • Kubernetes 1.16 is required to execute this fault.
  • The application pods should be in the running state before and after injecting chaos.

Fault tunables

Mandatory tunables

Tunable Description Notes
ATTRIBUTES Specify the file attributes and their values that need to be overridden For more information, go to attributes.
MOUNT_PATH The absolute mount path of the volume mounted to the target pod For more information, go to mount path.

Optional tunables

Tunable Description Notes
TARGET_CONTAINER Name of the container subject to IO attribute override If the value is not provided, the fault injects chaos on the first container of the pod. For more information, go to target specific container.
FILE_PATH The path for injecting faults can be specified as either a single file or a wildcard. If not provided, it will target all the files present inside the mount path For more information, go to file path.
PERCENTAGE The likelihood of failure per operation, expressed as a percentage For more information, go to percentage.
METHOD_TYPES This contains the file system call or methods For more information, go to percentage.
CONTAINER_RUNTIME Container runtime interface for the cluster Default: containerd. Supports docker, containerd and crio. For more information, go to container runtime .
SOCKET_PATH Path of the containerd or crio or docker socket file Defaults to /run/containerd/containerd.sock. For more information, go to socket path.
TOTAL_CHAOS_DURATION Duration to inject insert chaos (in seconds) Default: 60 s. For more information, go to duration of the chaos.
TARGET_PODS Comma-separated list of application pod names subject to pod io attribute override If not provided, the fault selects target pods randomly based on provided appLabels. For more information, go to target specific pods.
PODS_AFFECTED_PERC Percentage of total pods to target. Provide numeric values Default: 0 (corresponds to 1 replica). For more information, go to pod affected percentage.
RAMP_TIME Period to wait before and after injecting chaos (in seconds) For example, 30 s. For more information, go to ramp time.
SEQUENCE Sequence of chaos execution for multiple target pods Default: parallel. Supports serial and parallel. For more information, go to sequence of chaos execution.

Attributes

Modify the properties of files located within the mounted volume of the pod. Tune it by using the ATTRIBUTES environment variable.

The following YAML snippet illustrates the use of this environment variable:

# it overrides the file attributes
apiVersion: litmuschaos.io/v1alpha1
kind: ChaosEngine
metadata:
name: engine-nginx
spec:
engineState: "active"
annotationCheck: "false"
appinfo:
appns: "default"
applabel: "app=nginx"
appkind: "deployment"
chaosServiceAccount: litmus-admin
experiments:
- name: pod-io-attribute-override
spec:
components:
env:
# file attributes
- name: ATTRIBUTES
value: '{"perm": 72}'
- name: MOUNT_PATH
value: '/etc/config'
- name: TOTAL_CHAOS_DURATION
value: '60'

Mount Path

Mount path of the volume mounted to the target application. Tune it by using the MOUNT_PATH environment variable.

The following YAML snippet illustrates the use of this environment variable:

# it overrides the file attributes
apiVersion: litmuschaos.io/v1alpha1
kind: ChaosEngine
metadata:
name: engine-nginx
spec:
engineState: "active"
annotationCheck: "false"
appinfo:
appns: "default"
applabel: "app=nginx"
appkind: "deployment"
chaosServiceAccount: litmus-admin
experiments:
- name: pod-io-attribute-override
spec:
components:
env:
# mount path of the volume
- name: MOUNT_PATH
value: '/etc/config'
- name: ATTRIBUTES
value: '{"perm": 72}'
- name: TOTAL_CHAOS_DURATION
value: '60'

Advanced Fault Tunables

  • FILE_PATH: The path for injecting faults can be specified as either a single file or a wildcard. By default it targets all the files present inside the mount path.
  • PERCENTAGE: The likelihood of failure per operation, expressed as a percentage. Default is 100%.
  • METHOD_TYPES: This contains the file system call or methods. By default it targets all the methods.

The following YAML snippet illustrates the use of this environment variable:

# it overrides the file attributes
apiVersion: litmuschaos.io/v1alpha1
kind: ChaosEngine
metadata:
name: engine-nginx
spec:
engineState: "active"
annotationCheck: "false"
appinfo:
appns: "default"
applabel: "app=nginx"
appkind: "deployment"
chaosServiceAccount: litmus-admin
experiments:
- name: pod-io-attribute-override
spec:
components:
env:
# filter the target files
- name: FILE_PATH
value: '/etc/config/file.txt'
# percentage of i/o calls
- name: PERCENTAGE
value: '50'
# names of the io methods
- name: METHOD_TYPES
value: '["read","write"]'
- name: ATTRIBUTES
value: '{"perm": 72}'
- name: MOUNT_PATH
value: '/etc/config'
- name: TOTAL_CHAOS_DURATION
value: '60'

Container runtime and socket path

The CONTAINER_RUNTIME and SOCKET_PATH environment variables to set the container runtime and socket file path, respectively.

  • CONTAINER_RUNTIME: This supports docker, containerd, and crio runtimes. The default value is containerd.
  • SOCKET_PATH: This contains the path of containerd socket file by default(/run/containerd/containerd.sock). For docker, specify the path as /var/run/docker.sock. For crio, specify the path as /var/run/crio/crio.sock.

The following YAML snippet illustrates the use of these environment variables:

## provide the container runtime and socket file path
apiVersion: litmuschaos.io/v1alpha1
kind: ChaosEngine
metadata:
name: engine-nginx
spec:
engineState: "active"
annotationCheck: "false"
appinfo:
appns: "default"
applabel: "app=nginx"
appkind: "deployment"
chaosServiceAccount: litmus-admin
experiments:
- name: pod-io-attribute-override
spec:
components:
env:
# runtime for the container
# supports docker, containerd, crio
- name: CONTAINER_RUNTIME
value: 'containerd'
# path of the socket file
- name: SOCKET_PATH
value: '/run/containerd/containerd.sock'
- name: ATTRIBUTES
value: '{"perm": 72}'
- name: MOUNT_PATH
value: '/etc/config'
- name: TOTAL_CHAOS_DURATION
VALUE: '60'