How do you setup local environment variables for Cloud Functions for Firebase

As of now, you have to manually create a .runtimeconfig.json file inside your functions directory by running this command. Then run the serve command.

firebase functions:config:get > .runtimeconfig.json

If you are using Windows Powershell, replace the above with:

firebase functions:config:get | ac .runtimeconfig.json

You can learn more in https://firebase.google.com/docs/functions/local-emulator

For those who want to use the environment variables (process.env), I follow this workaround.

Set the config values before deploying

firebase functions:config:set envs.db_host=$DB_HOST_PROD envs.db_user=$DB_USER_PROD envs.db_password=$DB_PASSWORD_PROD envs.db_name=$DB_NAME_PROD envs.db_use_ssl=false

Read the config and update the env variables first thing under your functions code.

const functions = require('firebase-functions');
const config = functions.config();

// Porting envs from firebase config
for (const key in config.envs) {
    process.env[key.toUpperCase()] = config.envs[key];
}

You can keep a file called .env.json and load it when you trigger deploy command

{
  "name": "project",
  "version": "0.0.0",
  "scripts": {
    "deploy": "npm run env && firebase deploy --only functions",
    "env": "test -f env.json && firebase functions:config:unset env && firebase functions:config:set env=\"$(cat env.json)\" || echo \"Please add the file env.json before deploy.\""
  },
  "dependencies": {
    "firebase-functions": "^3.1.0"
  },
  "devDependencies": {
    "firebase-functions-test": "^0.1.6"
  }
}

I've narrowed down the issue to Windows Powershell.

Running firebase functions:config:get > .runtimeconfig.json in powershell generates a broken json I don't know why, which when parsed gives Unexpected token � in JSON at position 0.

I've managed to sort it out by running .runtimeconfig.json generation command in Windows command prompt.