Command Probe

Configure Command probes to run shell commands and validate output during chaos experiments

Command probe allows you to run shell commands and match the output as part of the entry or exit criteria. Use it to implement custom validation logic that goes beyond what HTTP or K8S probes offer.

The probe supports two execution modes:

• Inline mode (default): The command runs inside the experiment pod. Best for simple shell commands.

• Source mode: The command runs in a separate pod with a custom image. Best when application-specific binaries are needed.

When to use

• Query a database to verify data integrity during chaos (e.g., mysql -e "SELECT count(*) FROM orders")

• Parse application logs or JSON output to confirm expected behavior

• Run custom health checks that require application-specific CLIs or binaries (use source mode)

• Validate file system state, environment variables, or process status on the target system

Steps to configure

1. Navigate to Project Settings > Chaos Probes and click + New Probe

2. Select Command Probe and provide a name, and optionally a description and tags

3. Under Variables, define any reusable values you want to reference in probe properties or run properties. For each variable, specify the type (String or Number), name, value (fixed or runtime input), and whether it's required at runtime.

4. Under Probe Properties, configure:

   Field	Description
   Command	The shell command to execute (e.g., echo "Hello World")

   Under Data Comparison, provide the expected output criteria:

   Field	Description
   Type	Data type of the output: String, Int, or Float
   Comparison Criteria	For string: contains, equal, notEqual, matches, notMatches, oneOf. For int/float: >=, <=, ==, !=, >, <, oneOf, between
   Value	The expected value to compare against (e.g., Hello World)

   Optionally, enable Source mode to run the command in a separate pod. This is preferred when application-specific binaries are required.

   Field	Description
   Source (optional)	Toggle to enable source mode
   Environment Variables (optional)	Name-value pairs passed to the source pod

   When source mode is enabled, environment variables are not supported directly. You can reference values from ConfigMaps and Secrets instead.

5. Provide the Run Properties:

   Field	Description
   Timeout	Maximum time for probe execution (e.g., 10s)
   Interval	Time between successive executions (e.g., 2s)
   Attempt	Number of retry attempts (e.g., 1)
   Polling Interval	Time between retries (e.g., 30s)
   Initial Delay	Delay before first execution (e.g., 5s)
   Verbosity	Log detail level
   Stop On Failure (optional)	Stop the experiment if the probe fails

6. Click Create Probe

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Command Probe on Windows

The Windows command probe extends the standard command probe to support Windows Command Prompt (cmd) and PowerShell execution contexts.

Prerequisites

• Setup Windows chaos infrastructure

• Windows chaos faults

Steps to configure

1. Navigate to Project Settings > Chaos Probes and click + New Probe

2. Select Windows as your target infrastructure type, then select Command Probe

3. Enter a name, and optionally a description and tags

4. Under Probe Properties, configure:

   Field	Description
   Command	The command to execute (cmd or PowerShell)

   Under Data Comparison, provide:

   Field	Description
   Type	Data type of the output: String, Int, or Float
   Comparison Criteria	For string: contains, equal, notEqual, matches, notMatches, oneOf. For int/float: >=, <=, ==, !=, >, <, oneOf, between
   Value	The expected value to compare against

5. Provide the Run Properties:

   Field	Description
   Timeout	Maximum time for probe execution (e.g., 10s)
   Interval	Time between successive executions (e.g., 2s)
   Attempt	Number of retry attempts (e.g., 1)
   Polling Interval	Time between retries (e.g., 30s)
   Initial Delay	Delay before first execution (e.g., 5s)
   Verbosity	Log detail level
   Stop On Failure (optional)	Stop the experiment if the probe fails

6. Click Create Probe