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Command Probe

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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:

    FieldDescription
    CommandThe shell command to execute (e.g., echo "Hello World")

    Under Data Comparison, provide the expected output criteria:

    FieldDescription
    TypeData type of the output: String, Int, or Float
    Comparison CriteriaFor string: contains, equal, notEqual, matches, notMatches, oneOf. For int/float: >=, <=, ==, !=, >, <, oneOf, between
    ValueThe 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.

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

    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:

    FieldDescription
    TimeoutMaximum time for probe execution (e.g., 10s)
    IntervalTime between successive executions (e.g., 2s)
    AttemptNumber of retry attempts (e.g., 1)
    Polling IntervalTime between retries (e.g., 30s)
    Initial DelayDelay before first execution (e.g., 5s)
    VerbosityLog detail level
    Stop On Failure (optional)Stop the experiment if the probe fails

  6. Click Create Probe

Command Probe on Windows​

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

Prerequisites​

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. Enter the Command, Type, Comparison Criteria, and the Value

  5. Provide values for Timeout, Interval, Attempt, Polling Interval, and Verbosity. Click Create Probe

  6. Your Windows command probe is now ready to be attached to chaos experiments