Constraints

For more information on Constraints see Features - Constraints and Actions - Constraints

If your Feature or Action has Constraints to declare, then you must add the following to your class:

protected function constraints(\Lantern\Features\ConstraintsBuilder $constraints)
{
    //
}

Available constraints

classExists()

Ensure a specific class exists.

NB: This constraint will try to find the class with autoloading.

executableIsInstalled()

Ensure a specific binary is present on your system.

Paths

When Lantern searches for an executable, it must search certain paths on the server.

These paths can be configured in your AppServiceProvider.

extensionIsLoaded()

Ensure a particular PHP extension is loaded.

What extensions do you have?

To check the extensions loaded in your environment:

php -m

Constraint caching

When a Constraint is checked, the result of that check is cached. This is to avoid needlessly running the same check over and over again.

The whole point of a Constraint check is to ensure the Action is available within the current environment, and that environment is not expected to change within the same request.