Nuxt Generate + RealtimeDatabase / Firestore results in "Nuxt Generate finished but did not exit"

When using nuxt generate, the following warning appears at the end (after a successful generate)

Problem

⚠ Nuxt Warning 

The command 'nuxt generate' finished but did not exit after 5s
This is most likely not caused by a bug in Nuxt.js
Make sure to cleanup all timers and listeners you or your plugins/modules start.
Nuxt.js will now force exit

DeprecationWarning: Starting with Nuxt version 3 this will be a fatal error  

Possible Solution

It can theoretically be fixed by calling goOffline() for RealtimeDb or terminate() for Firestore after the generate:done hook.

export default {
  hooks: {
    generate: {
      done(builder) {
        $fireDb.goOffline()
        $fireStore.goOffline()
      }
    }
  },

• Problem now is: How do we access $fireDb or $fireStore in this hook and how do we implement this in nuxt-firebase?

Might be a big issue when Nuxt v3 arrives.

(Originated from https://github.com/lupas/nuxt-fire/issues/90#issuecomment-590052067)

[lupas]

Alright guys, so I found a way to make this work without having to create any additional files. Just do the following in your nuxt.config.js:

hooks: {
  generate: {
    async done(builder) {
      const appModule = await import('./.nuxt/firebase/app.js')
      const { session } = await appModule.default(
        builder.options.firebase.config,
        {
          res: null,
        }
      )
      try {
        session.database().goOffline()
      } catch (e) { }
      try {
        session.firestore().terminate()
      } catch (e) { }
    },
  },
},

What I am doing is:

1. Take the Firebase config out of builder.options.firebase.config
2. Get the Firebase instance from ./.nuxt/firebase/app.js
3. Call goOffline() / terminate() on RealtimeDatabase and Firestore through that instance

I assume that with Nuxt 3 the API and possibly the hooks will change quite a bit so that this has to be reevaluated anyway (maybe we can access the context in the hooks then?). Until Nuxt 3 is released (possibly around Q1 2021) this should be a good workaround.

ToDo’s

• Check if this can be included in the module by directly extending the generate:done hook
• Document in the docs (https://github.com/nuxt-community/firebase-module/commit/3535d3994fe397715fd324274277cb7349204c50)

[EvanLomas]

So a short-term solution I’ve determined from these two posts is:

1. Move your firebase config to a shared file such as {project_root}/firebase.config.js:

module.exports = {
  apiKey: "...",
  authDomain: "...",
  databaseURL: "...",
  projectId: "...",
  storageBucket: "...",
  messagingSenderId: "...",
  appId: "...",
  measurementId: "..."
}

1. Create a plugins/firebaseInit.js file:

import firebase from 'firebase/app'
import 'firebase/database'
import 'firebase/firestore'

if (!firebase.apps.length) {
  firebase.initializeApp(require('../firebase.config.js'))
}

export const fireDb = firebase.database()
export const fireStore = firebase.firestore()

1. Change your nuxt.config.js to import the config file and add a generate.done() hook around the plugin:

import { fireDb, fireStore } from './plugins/firebaseInit.js'

export default {
  // ...
  modules: [
    // ...
    [
      '@nuxtjs/firebase',
      {
        config: require('./firebase.config.js'),
        services: {
          auth: true,
          realtimeDb: true,
          firestore: true,
          // ...
        }
      }
    ]
  ],
  // ...
  hooks: {
    generate: {
      done(builder) {
        try { fireDb.goOffline() } catch (e) { }
        try { fireStore.terminate() } catch (e) { }
      }
    }
  }
}