Probes
Probes are validation mechanisms that continuously monitor and verify the health and behavior of your system throughout chaos experiments. They act as automated checkpoints that help you:
- Validate system resilience - Verify that your applications and infrastructure maintain expected behavior under failure conditions
- Define success criteria - Set clear, measurable conditions that determine whether an experiment passes or fails
- Collect evidence - Gather real-time data about system state, performance metrics, and application health
- Automate validation - Replace manual observation with automated checks that run at specific points during experiments
Probes can query various data sources including HTTP endpoints, command outputs, Kubernetes resources, and APM systems to provide comprehensive visibility into your system's resilience.
- Old Chaos Studio: Probes are scoped to individual faults and execute only during fault injection
- New Chaos Studio: Probes operate along the entire experiment lifecycle and can be configured to run before, during, and after the complete experiment execution
Probe Verification
Probes can be marked as Verified to ensure only tested and approved probes are used in production experiments. This governance feature helps teams:
- Maintain quality standards - Only allow probes that have been validated and approved by your team
- Prevent misconfigurations - Reduce the risk of using untested or incorrectly configured probes in critical experiments
- Enforce compliance - Use with ChaosGuard policies to mandate that only verified probes can be executed
How to Mark a Probe as Verified
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Navigate to the Probes & Actions section in the Chaos Engineering module
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Locate the probe you want to verify
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Click on the three-dot menu (⋮) next to the probe
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Select Mark as Verified
Once marked as verified, the probe will display a green checkmark (✓) in the Verification Status column. You can then configure ChaosGuard conditions to allow only verified probes in your experiments, adding an extra layer of safety and governance.
Combine probe verification with ChaosGuard policies to create a robust governance framework that ensures only approved, tested probes are used in your chaos experiments.
Variables
Variables allow you to define reusable, parameterized values that can be referenced in Probe Properties and Run Properties during probe configuration. This is the second step in the probe creation wizard and applies to all probe types.
Variables are useful when you want to:
- Reuse values across multiple probe configuration fields without repeating them
- Inject runtime values into probe properties at experiment execution time
- Centralize configuration - update a variable once and have it reflected wherever it is used
Adding a Variable
When creating or editing a probe, navigate to the Variables step and click + Add Variable. Each variable has the following fields:
| Field | Description |
|---|---|
| Type | Data type of the variable. Supported types: String, Number |
| Name | Identifier used to reference the variable in probe/run properties |
| Value | The value assigned to the variable - can be a fixed value or a runtime input |
| Set variable as required during runtime | When checked, the variable must be supplied at experiment run time |
| Description | Optional description for the variable |
Value Types
- Fixed value - A static value set at probe creation time. The value remains constant across experiment runs.
- Runtime input - The value is provided at experiment execution time (shown as
<+input>in the variables list). Use this when the value may differ between runs.
Using Variables in Chaos Studio
When you add a probe to an experiment in the Chaos Studio, the probe panel shows a Variables tab alongside Probe Properties and Configuration. Any input variables defined on the probe appear here, allowing you to supply or override values for that specific experiment run before applying changes.
Probe Properties
When configuring probes in the Chaos Studio, all configuration fields are available in the Probe Properties tab. This unified interface provides a streamlined experience by consolidating all probe settings in a single location.
The Probe Properties tab includes:
- Probe-specific settings: Application Name, Duration, Metric paths, Timeout values, Polling intervals, Criteria, and other probe type-specific configurations
- Run Properties: Attempt, Interval, Initial Delay, Polling Interval, Timeout, Stop On Failure
All probe configuration has been consolidated into the Probe Properties tab. Previously, some inputs were managed in a separate "Variables" tab. This change simplifies the configuration experience by keeping all probe settings together in one place, making it easier to configure and review your probe setup.
Probe Types
Select the probe type you want to learn more about:
Built-in Probe Templates
Harness provides pre-built Command Probe templates to help you quickly validate common scenarios in your chaos experiments. These templates are ready to use and can be customized to fit your specific requirements.
Currently, built-in templates are available for Command Probes targeting Kubernetes infrastructure. Templates for other probe types and platforms will be added in future releases.
Next Steps
- Create Chaos Experiments - Build experiments with probes for validation