Rules

Once we have a trigger and some actions, we can create rules for the trigger. A rule connects the trigger with an action, so if you fire the trigger, it will invoke the action. Let’s see this in practice in the next listing.

Create data

First of all, create a file called alert.js.

function main() {
  console.log("Suspicious activity!");
  return {
    result: "Suspicious activity!"
  };
}

Then, create a Nuv action for this file:

$ nuv action create alert alert.js

Now, create a trigger that we’ll call notifyAlert:

$ nuv trigger create notifyAlert

Now, all is ready, and now we can create our rule! The syntax follows this pattern: "nuv rule create {ruleName} {triggerName} {actionName}".

$ nuv rule create alertRule notifyAlert alert

Test your rule

Our environment can now be alerted if something suspicious occurs! Before starting, let’s open another terminal window and enable polling (with the command nuv activation poll) to see what happens.

$ nuv activation poll
Enter Ctrl-c to exit.
Polling for activation logs

It’s time to fire the trigger!

$ nuv trigger fire notifyAlert
ok: triggered /notifyAlert with id 86b8d33f64b845f8b8d33f64b8f5f887

Now, go to see the result! Check the terminal where you are polling activations now!

Enter Ctrl-c to exit.
Polling for activation logs

Activation: 'alert' (dfb43932d304483db43932d304383dcf)
[
    "2024-02-20T03:15.15472494535Z stdout: Suspicious activity!"
]

Conclusion

As with all the other commands, you can execute list, update, and delete by name.

A trigger can enable multiple rules, so firing one trigger actually activates multiple actions. Rules can also be enabled and disabled without removing them. As in the last example, let’s try to disable the first rule and fire the trigger again to see what happens.

$ nuv rule disable alertRule    (1)
ok: disabled rule alertRule
$ nuv trigger fire notifyAlert  (2)
ok: triggered /_/notifyAlert with id 0f4fa69d910f4c738fa69d910f9c73af

1	Disabling the rule.
2	Firing the trigger again.

In the activation polling window, we can see that no action is executed now. Of course, we can enable the rule again with:

nuv rule enable alertRule