[q]Autoload with dependencies

[SkeLLLa]

Fastify plugin module support dependencies section. If some plugins wrapped with fastify-plugin registered through autoload, then it checks only plugins, that are loaded through autoload. However it ignores plugins that are previously loaded with fastify.register.

Is that correct behaviour? Or it should check Symbol(registered-plugin) in fastify instance as well?

[mcollina]

Can you make an example where this behavior is failing you? How would you change this?

[SkeLLLa]

@mcollina
Consider we have the following structure

const fastify = require('fastify')();
const externalPlugin = require('fastify-external-plugin');
const autoloadPlugin = require('fastify-autoload');
fastify.register(externalPlugin);
fastify.register(autoloadPlugin, {dir: './plugins'});

... // await for fastify.ready and listen

As an fastify-external-plugin we could have fastify-mongo plugin, for example, and couple of own custom plugins are loaded through autoload plugin from plugins dir. Our own plugins depend or use functionality from fastify-mongo module. So in that case we should define dependency on fastify-mongo module. And now fastify-autoload plugin will search that module inside directory provided in options, but it will not check modules registered through fastify.register function.

Obviously we can set dependency to decorators and wait until fastify.mongo decorator will be available. However I think there could be a case when our custom plugins could depend on some other plugin that doesn't decorate fastify instance.

[mcollina]

Fastify does not resolve the dependency graph, because plugins are loaded in-order by fastify. This plugin needs that, because it would load them from the order that they are being returned from the file system.

Essentially, the dependency order thing is needed to solve a problem added by autoload, and only on plugins registered by autoload.

If you need fastify.mongo before the plugins returned by autoload, then register it before then. Maybe I'm not really understanding your issue. Would you mind crafting a little repo?

[salmanm]

I realise what @SkeLLLa means is if we have a plugin as

const fp = require('fastify-plugin')

function plugin (f, opts, next) {
  // plugin body

  next()
}

module.exports = fp(plugin, {
  name: 'plugin-g',
  dependencies: ['fastify-sensible']
})

The new feature of automatically resolving dependencies won't find fastify-sensible in the list of available plugins, because its being registered manually.

The problem sounds legit. Do you have any suggestion on how to tackle this? @mcollina

[mcollina]

I think the best suggestion if a plugin is missing is to assume that is loaded by fastify and rely on https://github.com/fastify/fastify/blob/e2062efcc7adbb82101e3afd7734835f81d71bbe/lib/pluginUtils.js#L29 this check. It will throw if it's missing, and that's ok.

[salmanm]

Yea that sounds good. Something like this? #32.

I'll add test if the PR is fine. Done.

[stale]

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