DevelopmentEnvironment Variables

Environment Variables

Comma uses a .env file for configuration that varies between development and production builds.

Setup

cp .env.example .env

Then edit .env with your values. The file is gitignored — never commit it.

Variables

GOOGLE_WEB_CLIENT_ID

Required for Google Drive backup and cloud sync.

GOOGLE_WEB_CLIENT_ID=123456789-abcdefghijklmnop.apps.googleusercontent.com

This is the client ID for your Web OAuth client in Google Cloud Console. It is used:

  • On web (Expo web builds) for the OAuth redirect flow
  • On Android as the webClientId in @react-native-google-signin/google-signin’s configuration

Getting the Google OAuth client ID

Step 1 — Create a Google Cloud project

  1. Go to Google Cloud Console.
  2. Create a new project (or use an existing one).
  3. Navigate to APIs & Services → Library.
  4. Enable the Google Drive API.

Step 2 — Configure the OAuth consent screen

  1. Go to APIs & Services → OAuth consent screen.
  2. Choose External user type.
  3. Fill in app name (e.g. “Comma”) and your email.
  4. Under Scopes, add:
    • https://www.googleapis.com/auth/drive.appdata
  5. Add test users if you’re in development (before publishing).

Step 3 — Create OAuth credentials

You need credentials for each platform you’re targeting:

Web client (always required)

  1. Go to APIs & Services → Credentials → Create Credentials → OAuth Client ID.
  2. Type: Web application.
  3. Add http://localhost to Authorized JavaScript origins (for Expo dev).
  4. Copy the Client ID → this is your GOOGLE_WEB_CLIENT_ID.

Android client

  1. Create Credentials → OAuth Client ID → Android.
  2. Package name: app.comma.tracker (or your package name from app.json).
  3. SHA-1 fingerprint: get your debug keystore SHA-1: 
    cd android && ./gradlew signingReport
    For release, use your upload keystore SHA-1.
  4. Copy the Client ID — you don’t need this in .env, but it must exist in the Google Cloud project for Android sign-in to work.

iOS client

  1. Create Credentials → OAuth Client ID → iOS.
  2. Bundle ID: app.comma.tracker (or your bundle ID).
  3. Copy the Client ID — not needed in .env, but must exist for iOS sign-in.

.env.example reference

# Google OAuth Web Client ID
# Required for Google Drive backup and cloud sync on all platforms.
# Create at: console.cloud.google.com → APIs & Services → Credentials
GOOGLE_WEB_CLIENT_ID=
 
# Optional: override the default log level (debug | info | warn | error)
# LOG_LEVEL=info

How env vars are loaded

Expo loads .env automatically via dotenv. Values are available in JavaScript as process.env.GOOGLE_WEB_CLIENT_ID.

In src/config/google.ts:

export const GOOGLE_WEB_CLIENT_ID = process.env.GOOGLE_WEB_CLIENT_ID ?? ''

This is the only file that reads the env var — all other files import from src/config/google.ts.

EAS Build (CI/CD)

If you use Expo Application Services (EAS Build), set secrets in the EAS dashboard rather than committing a .env file:

eas secret:create --scope project --name GOOGLE_WEB_CLIENT_ID --value "your-client-id"

EAS injects these as environment variables during the build.

Project StructureNative Module: comma-tracker