(node.js) how to use environment variables in JSON file

Question

I'm using a 3rd party library that needs a JSON config file, and I need to pass some env variables in as key values. If I include them as I normally would, eg:

  "s3": {
    "key": process.env.AWS_ACCESS_KEY_ID,
    "secret": process.env.AWS_SECRET_ACCESS_KEY,
    "bucket": process.env.S3_MLL_BUCKET_NAME,
    "destination": "/backups/database",
    "encrypt": false,
    "region": process.env.AWS_REGION
  }

...I get the error:

SyntaxError: config/s3_backup.config.json: Unexpected token p

Answer 1

JSON does not have notion of environment variables. What you can do though is to declare your configuration file as node.js module and then you will be able to use your environment variables as follows:

module.exports = {
  s3: {
    key: process.env.AWS_ACCESS_KEY_ID,
    secret: process.env.AWS_SECRET_ACCESS_KEY,
    bucket: process.env.S3_MLL_BUCKET_NAME,
    destination: "/backups/database",
    encrypt: false,
    region: process.env.AWS_REGION
  }
};

Answer 2

I had the same issue, what worked for me was using a js file and exporting an object module.exports = {config: {"exampleAPIKey":"ruier4343"}} ...then "stringifying" the object and then parsing it back to json const config = require("./jsConfigs.js").config; const jsonConfig = JSON.parse(JSON.stringify(config)) const config = require("./jsConfigs.js").config; const jsonConfig = JSON.parse(JSON.stringify(config)) I had tried it so many different ways but this is the only one that worked.

Answer 3

I faced similar issue where i have to pass Env variables inside config.json and my 3rd party system accepts mainly config.json.

Here is the workaround that worked for me.

1. My app.js gets executed inside start script of package.json
2. So During Runtime (ie deployment which runs command 'npm run start') it will update config.json dynamically using below code placed inside app.js (before creating server).

App.js

    //updating config.json to use environment variables during run time
    const fs = require('fs');
    const fileName = './public/config.json';
    const file = require(fileName);
    if (file && file.arguments && file.arguments.execute)
        file.arguments.execute.url = process.env.executeUrl || "";

    if (file && file.configurationArguments && file.configurationArguments.publish)
        file.configurationArguments.publish.url = process.env.publishUrl || "";

    fs.writeFile(fileName, JSON.stringify(file, null, 2), function writeJSON(err) {
        if (err)
            return console.log(err);
        console.log('updated config.json');
    });
    http.createServer(app).listen(app.get('port'), function() {
        console.log('App Express server listening on port ' + app.get('port'));
    });