Rudder techniques

condition_from_command

Execute a command and create result conditions depending on its exit code.

⚙️ Compatible targets: Linux, Windows

Parameters

Outcome conditions

You need to replace ${condition} with its actual canonified value.

• ✅ Ok: condition_from_command_${condition}_ok
  • ☑️ Already compliant: condition_from_command_${condition}_kept
  • 🟨 Repaired: condition_from_command_${condition}_repaired
• ❌ Error: condition_from_command_${condition}_error

Example

method: condition_from_command
params:
  command: VALUE
  condition: VALUE
  true_codes: VALUE
  false_codes: VALUE

Documentation

This method executes a command, and defines a ${condition}_true or a ${condition}_false condition depending on the result of the command:

• If the exit code is in the "True codes" list, this will produce a kept outcome and a ${condition}_true condition,
• If the exit code is in the "False codes" list, this will produce a kept outcome and a ${condition}_false condition,
• If the exit code is not in "True codes" nor in "False codes", or if the command can not be found, it will produce an error outcome and and no condition from ${condition}

The created condition is global to the agent.

Windows

On Windows nodes, the exit code is taken from the LASTEXITCODE which is defined either by:

• The exit code of a binary execution (when the command a call to an exe)
• The return code of a Powershell script

Direct Powershell execution will almost always return 0 as LASTEXITCODE value, meaning that you have to execute either a binary or a Powershell script to control the return code.

Example:

If you run a command /bin/check_network_status that output code 0, 1 or 2 in case of correct configuration, and 18 or 52 in case of invalid configuration, and you want to define a condition based on its execution result, you can use:

condition_from_command("network_correctly_defined", "/bin/check_network_status", "0,1,2", "18,52")

• If the command exits with 0, 1 or 2, then it will define the conditions

  • network_correctly_defined_true,
  • condition_from_command_network_correctly_defined_kept,
  • condition_from_command_network_correctly_defined_reached,

• If the command exits 18, 52, then it will define the conditions

  • network_correctly_defined_false,
  • condition_from_command_network_correctly_defined_kept,
  • condition_from_command_network_correctly_defined_reached

• If the command exits any other code or is not found, then it will define the conditions

  • condition_from_command_network_correctly_defined_error,
  • condition_from_command_network_correctly_defined_reached

Notes:

• In audit mode, this method will still execute the command passed in parameter. Which means that you should only pass non system-impacting commands to this method.

• Rudder will automatically "canonify" the given Condition prefix at execution time, which means that all non [a-zA-Z0-9_] characters will be replaced by an underscore.