Load custom configuration runtime - node.js

Question

I have a nuxt application in which I will need to append data from a generated configuration file when the application is first started. The reason I cannot do this in the actual build is because the configuration file does not exists at this point; it is generated just before calling npm start by a bootstrap script.
Why don't I generated the configuration file before starting the application you may ask and this is because the application is run in a docker container and the built image cannot include environment specific configuration files since it should be used on different environments such as testing, staging and production.
Currently I am trying to use a hook to solve this, but I am not really sure on how to actually set the configuration data in the application so it can be used everywhere:
# part of nuxt.config.js
hooks: {
listen(server, listener) {
# load the custom configuration file.
fs.readFile('./config.json', (err, data) => {
let configData = JSON.parse(data));
});
}
},
The above hook is fired when the application first starts to listen for connecting clients. Not sure this is the best or even a possible way to go.
I also made an attempt of using a plugin to solve this:
import axios from ‘axios’;
export default function (ctx, inject) {
// server-side logic
if (ctx.isServer) {
// here I would like to simply use fs.readFile to load the configuration, but this is not working?
} else {
// client-side logic
axios.get(‘/config.json’)
.then((res) => {
inject(‘storeViews’, res.data);
});
}
};
In the above code I have problems both with using the fs module and axios.
I was also thinking about using a middleware to do this, but not sure on how to proceed.

Answer 1

If someone else has this kind of problem here is the solution I came up with in the end:
// plugins/config.js
class Settings
{
constructor (app, req) {
if (process.server) {
// Server side we load the file simply by using fs
const fs = require('fs');
this.json = fs.readFileSync('config.json');
} else {
// Client side we make a request to the server
fetch('/config')
.then((response) => {
if (response.ok) {
return response.json();
}
})
.then((json) => {
this.json = json;
});
}
}
}
export default function ({ req, app }, inject) {
inject('config', new Settings(app, req));
};
For this to work we need to use a server middleware:
// api/config.js
const fs = require('fs');
const express = require('express');
const app = express();
// Here we pick up requests to /config and reads and return the
// contents of the configuration file
app.get('/', (req, res) => {
fs.readFile('config.json', (err, contents) => {
if (err) {
throw err;
}
res.set('Content-Type', 'application/json');
res.end(contents);
});
});
module.exports = {
path: '/config',
handler: app
};