Loading .env files

Looking for runtime environment variables? This page only covers loading local .env files for use during osls commands — it does not set environment variables on your deployed Lambda functions. To configure variables in the function runtime, see Environment Variables in the Functions guide. To reference machine environment variables inside serverless.yml, see the ${env:} source in the Variables guide.

To automatically load environment variables from .env files (with the help of the dotenv package), set useDotenv: true in serverless.yml:

useDotenv: true

With that option enabled, .env files will also be excluded from the package in order to avoid uploading sensitive data as a part of a package by mistake.

Support for .env files

osls loads .env.{stage} from the service directory when present; otherwise it falls back to .env. If stage is not explicitly defined, it defaults to dev. Invalid stage names are rejected before .env.{stage} is read.

osls loads .env files quietly by default. Avoid DOTENV_CONFIG_DEBUG=true or DOTENV_CONFIG_QUIET=false when using machine-readable commands such as osls print, or when using osls compose, because those dotenv options can write runtime loading messages to stdout.

Variable expansion

It is possible to define environment variables as a combination of existing ones:

BASE_URL=my.api.com
PROTOCOL=https

URL=$PROTOCOL/$BASE_URL

This is supported through dotenv-expand

Differences against serverless-dotenv-plugin

There are a few differences between above functionality and serverless-dotenv-plugin:

• osls only loads environment variables locally and does not pass them to your function's environment
• osls loads variables from only one .env file (if stage-specific .env is found, default .env is not loaded)
• osls does not support .env.local, .env.{stage}.local, and .env.development files in a similar way to the plugin
• osls does not use NODE_ENV variable and --env flag when determining stage