How to use both root and app level env files with turborepo

I have a monorepo with the following script:

"start": "env-cmd -f .env turbo run start --parallel",

If I run yarn start at the root, it runs all my apps using the .env file at the root.

A lot of my environment variables are only used in one specific app and my /.env file is getting cluttered as I keep on adding new apps. I want to keep that .env file for shared environment variables only and have children .env files at the root of each apps for specific configurations.

Example if I have an app called web located in /apps/web, I would like to add an /apps/web/.env file that is used only when building the web app.

How can I achieve that ?

1. You can leave your global envs in monorepo root .env file. They will be available in all your workspaces by default.
2. You should add dotenv-cli package as dev_deps for workspaces that require .env file with workspace-specific variables.
3. Update your scripts in package.json:

• Add "with-env": "dotenv -e ./.env --"
• Update "dev": "pnpm with-env next dev",
• Update "build": "pnpm with-env next build"

4. Remove all workspace-specific envs from monorepo root .env file (and
   from turbo.json globalEnvs and add .env files (with workspace-specific envs) to your workspaces to the root (package.json level).

Not sure how to run both root and app level, but if you want just the app level, do the following:

1. in your root turbo.json put in all the keys:

"globalEnv": [
  "MY_KEY",
  "MY_OTHER_KEY"
],
//a. ".env" is the default, you don't need the following line unless you have a custom .env file name. e,.g. .env.local
//b. Note "globalDependencies" in the following line is referring to your .env file under the app folder, not the root one.
"globalDependencies": [".env.local"] 

2. in your web project, put your .env or .env.local file there.

MY_KEY='SOMETHING'
MY_OTHER_KEY='SOMETHING ELSE'

3. Clear all your cache in the cache folder (just in case), then run:

turbo run dev --filter=my-web-project

That's it, your web app will pick up the env file in your app folder, not from your root folder.

ref: https://turbo.build/repo/docs/reference/configuration#globalEnv