Actions

AMPS provides the ability to run scheduled tasks or respond to events, such as Linux signals, using the Actions interface.

To create an action, you add an Actions section to the AMPS configuration file. Each Action contains one (or more) On statement which specifies when the action occurs, and one (or more) Do statement which specifies what the AMPS server does for the action. Within an action, AMPS performs each Do statement in the order in which they appear in the file.

AMPS actions may require the use of parameters. AMPS allows you to use variables in the parameters of an action. You can access these variables using the following syntax:

{{VARIABLE_NAME}}

AMPS defines a set of default variables when running an action. The event, or a previous action, can add variables in the context of the action. Those variables can be expanded in subsequent parameters. If a variable is used that isn't defined at the point where it is used, AMPS will expand that variable to an empty string literal. The context can also be updated as the module is running, so any variables that are available at any given point in the file depend on what action was previously executed.

By default, AMPS loads the following variables when it initializes an AMPS action:

Variable

Description

An example to echo a message when AMPS starts up is shown below. Note the AMPS_INSTANCE_NAME is one of the variables that AMPS pushes to the context when an action is loaded.

<Actions>
    <Action>
        <On>
            <Module>amps-action-on-startup</Module>
        </On>
        <Do>
            <Module>amps-action-do-echo-message</Module>
            <Options>
                <Message>instance={{AMPS_INSTANCE_NAME}}</Message>
            </Options>
        </Do>
    </Action>
</Actions>

AMPS actions are implemented as AMPS modules. To run each statement, AMPS simply calls the module that implements that Do statement. The module is free to take any necessary actions. If a Do statement returns a failure, AMPS does not run subsequent Do statements in that action. This is intended to help make maintenance processes reliable. For example, if a Do statement that is intended to copy a log file to a storage directory fails because the device that holds the storage directory is not mounted, further steps in the action -- which might do things like remove the log file from the original directory -- should not be run. Likewise, if AMPS exits unexpectedly during a given Do statement, subsequent statements will not be run.

AMPS provides the following modules by default:

On: Choosing When an Action Runs

The following table lists the On actions that are provided in AMPS by default. Details for each action are provided in the section describing that action.

Do: Choosing What an Action Does

The following table lists the Do actions that are provided in AMPS by default. Details for each action are provided in the section describing that action.

Conditionally Stop an Action

The following table lists the If actions that are provided in AMPS by default. Details for each action are provided in the section describing that action.

Examples

See the configuration section of the AMPS documentation for examples of action configuration.

PreviousEntitlement NextConfiguration for Actions

Last updated 1 month ago

Variable

Description

<Actions> <Action> <On> <Module>amps-action-on-startup</Module> </On> <Do> <Module>amps-action-do-echo-message</Module> <Options> <Message>instance={{AMPS_INSTANCE_NAME}}</Message> </Options> </Do> </Action> </Actions>

Condition

Modules

Action

Module

Condition

Module