Basic Usage

In this section, we will create a simple container using createContainer and run it with compose.up. This example will show how to start using the library and understand its basic ideas.

The container we create will have an identifier, domain, and a start function that runs when the container starts. We will also see how compose.up connects containers and controls their execution.

Analogy from Cooking

Imagine you are in a kitchen. You have a chef, ingredients, and a pot. Each of them is a container.

A chef alone can’t cook without ingredients. Ingredients won’t turn into a meal without a pot.

Containers don’t do much on their own, but when they work together, you get a finished meal. compose.up is the one that organizes the process, makes sure everything happens in the right order, and starts each part at the right time.

Example

import { createContainer, compose } from '@grlt-hub/app-compose';

const hireChef = () => null;

const chef = createContainer({
  // The name of our chef.
  id: 'John Doe',
  // This chef specializes in Italian cuisine.
  domain: 'italian-chef',
  start: async () => {
    // For example, we are hiring a chef.
    const hiredChef = await hireChef();

    console.log('The chef is already on the way!');

    // Every start function should return an object like this:
    // { api: object | null }
    return { api: hiredChef };
  },
});

const { up } = await compose({
  stages: [['prepare', [chef]]],
});

When you run this code, you should see the following output in the console:

> npm start
The chef is already on the way!

Try it

What’s Next?

In this example, we created a simple container that works alone. But in real applications, containers often depend on other containers to do their job.

Next, we will learn about dependencies and optionalDependencies. You’ll see how to connect containers and build flexible applications where different parts work together.