Simulate Time Faults

TimeChaos Introduction

Chaos Mesh provides the TimeChaos experiment type. You can use this experiment type to simulate a time offset scenario. This document describes how to create a TimeChaos experiment and its associated configuration file.

note

TimeChaos only affects the PID 1 process in the PID namespace of the container, and child processes of the PID 1. For example, the process started by kubectl exec does not be affected.

You can create experiments in Chaos Dashboard or using the YAML configuration file.

Create experiments using Chaos Dashboard

Open Chaos Dashboard, and click NEW EXPERIMENT on the page to create a new experiment:
In the Choose a Target area, choose CLOCK SCREW and fill out the Clock ID and time offset.
Fill out the experiment information, and specify the experiment scope and the scheduled experiment duration:
Submit the experiment information.

Create experiments using the YAML file

Write the experiment configuration to the YAML configuration file. In the following example, the time-shift.yaml file is used.
```
apiVersion: chaos-mesh.org/v1alpha1
kind: TimeChaos
metadata:
  name: time-shift-example
  namespace: chaos-testing
spec:
  mode: one
  selector:
    labelSelectors:
      'app': 'app1'
  timeOffset: '-10m100ns'
```
This experiment configuration will shift the time of the processes in the specified Pod forward by 10 minutes and 100 nanoseconds.
After the configuration file is prepared, use kubectl to create an experiment:
```
kubectl apply -f time-shift.yaml
```

The fields in the YAML configuration file are described in the following table:

Parameter	Type	Note	Default value	Required	Example
timeOffset	string	Specifies the length of time offset.	None	Yes	`-5m`
clockIds	[]string	Specifies the ID of clock that will be offset. See the clock_gettime documentation for details.	`[“CLOCK_REALTIME”]`	No	`[“CLOCK_REALTIME”, “CLOCK_MONOTONIC”]`
mode	string	Specifies the mode of the experiment. The mode options include `one` (selecting a random Pod), `all` (selecting all eligible Pods), `fixed` (selecting a specified number of eligible Pods), `fixed-percent` (selecting a specified percentage of Pods from the eligible Pods), and `random-max-percent` (selecting the maximum percentage of Pods from the eligible Pods).	None	Yes	`one`
value	string	Provides parameters for the `mode` configuration, depending on `mode`.For example, when `mode` is set to `fixed-percent`, `value` specifies the percentage of Pods.	None	No	1
containerNames	[]string	Specifies the name of the container into which the fault is injected.	None	No	`[“nginx”]`
selector	struct	Specifies the target Pod. For details, refer to Define the experiment scope.	None	Yes