How to programmatically apply a Drupal recipe (works in 10.3 and later)

apply-a-recipe.php

<?php

use Drupal\Core\Batch\BatchBuilder;
use Drupal\Core\Recipe\Recipe;
use Drupal\Core\Recipe\RecipeRunner;

// There are two ways to apply a recipe programmatically: immediately, or as a batch job.
// The batch job is generally the safer option, since more complex recipes could risk
// timing out if they try to do too much at once.

// So, first thing you need to do is get a Recipe object. Point it to the directoy where
// recipe.yml is:
$recipe = Recipe::createFromDirectory('/path/of/some/recipe');

// Now, if you want to make that a batch job:

$batch = new BatchBuilder();
foreach (RecipeRunner::toBatchOperations($recipe) as $operation) {
  $batch->addOperation(...$operation);
}

// Maybe you do other stuff with $batch here, like adding more operations, setting up the messages, etc.

// Finally, to kick off the job:
batch_set($batch->toArray());

// And that's that.

// If you want to just immediately apply the recipe, without giving the user any feedback, that's even
// easier:

RecipeRunner::processRecipe($recipe);

// Done-zo.

// By the way, BOTH of these techniques will automatically apply all the recipes that $recipe depends upon. You don't
// have to worry about setting it up or recursing or any of that nonsense. Just let the recipe system handle it for you.