Plugin type mismatch when using fastify-metrics in an ESM project

[FredTreg]

Since some 3rd party librairies I use in my project are now only packaged for ESM, I decided to migrate my TypeScript project from CommonJS to ESM ("module": "nodenext" and "moduleResolution": "nodenext" in tsconfig.json)

I have an issue with fastify-metrics: when registering, the type of metricsPlugin is no longer considered as matching the expected type :

import metricsPlugin from 'fastify-metrics'
...
fastify.register(metricsPlugin, { endpoint: '/metrics' })

=>

src/app.ts:52:18 - error TS2769: No overload matches this call.
  Overload 1 of 3, '(plugin: FastifyPluginCallback<{ endpoint: string; }, RawServerDefault, FastifyTypeProvider, FastifyBaseLogger>, opts?: FastifyRegisterOptions<...> | undefined): FastifyInstance<...> & PromiseLike<...>', gave the following error.
    Argument of type 'typeof import("/workspace/coucou/server/node_modules/fastify-metrics/dist/index")' is not assignable to parameter of type 'FastifyPluginCallback<{ endpoint: string; }, RawServerDefault, FastifyTypeProvider, FastifyBaseLogger>'.
      Type 'typeof import("/workspace/coucou/server/node_modules/fastify-metrics/dist/index")' provides no match for the signature '(instance: FastifyInstance<RawServerDefault, IncomingMessage, ServerResponse<IncomingMessage>, FastifyBaseLogger, FastifyTypeProvider>, opts: { ...; }, done: (err?: Error | undefined) => void): void'.
  Overload 2 of 3, '(plugin: FastifyPluginAsync<{ endpoint: string; }, RawServerDefault, FastifyTypeProvider, FastifyBaseLogger>, opts?: FastifyRegisterOptions<...> | undefined): FastifyInstance<...> & PromiseLike<...>', gave the following error.
    Argument of type 'typeof import("/workspace/coucou/server/node_modules/fastify-metrics/dist/index")' is not assignable to parameter of type 'FastifyPluginAsync<{ endpoint: string; }, RawServerDefault, FastifyTypeProvider, FastifyBaseLogger>'.
      Type 'typeof import("/workspace/coucou/server/node_modules/fastify-metrics/dist/index")' provides no match for the signature '(instance: FastifyInstance<RawServerDefault, IncomingMessage, ServerResponse<IncomingMessage>, FastifyBaseLogger, FastifyTypeProvider>, opts: { ...; }): Promise<...>'.
  Overload 3 of 3, '(plugin: FastifyPluginCallback<{ endpoint: string; }, RawServerDefault, FastifyTypeProvider, FastifyBaseLogger> | FastifyPluginAsync<...> | Promise<...> | Promise<...>, opts?: FastifyRegisterOptions<...> | undefined): FastifyInstance<...> & PromiseLike<...>', gave the following error.
    Argument of type 'typeof import("/workspace/coucou/server/node_modules/fastify-metrics/dist/index")' is not assignable to parameter of type 'FastifyPluginCallback<{ endpoint: string; }, RawServerDefault, FastifyTypeProvider, FastifyBaseLogger> | FastifyPluginAsync<...> | Promise<...> | Promise<...>'.

52 fastify.register(metricsPlugin, { endpoint: '/metrics' })

Am I doing something wrong? It worked when my project was CommonJS.

As a workaround I did this:

fastify.register(metricsPlugin as unknown as FastifyPluginAsync<Partial<IMetricsPluginOptions>>, {
  endpoint: '/metrics'
})

[SkeLLLa]

Hi. This plugin doesn't support ESM. And for now I don't have a plans for making it ESM-compatible. However if you want to try implement ESM support, you're more than welcome.

[dannycobussen]

I'm using the following as a "workaround".

import fastifyMetrics from "fastify-metrics";
...
fastify.register(fastifyMetrics.default, { endpoint: "/metrics" });

[FredTreg]

Thanks @dannycobussen for the workaround, my syntax was not working in fact.