Loading environment variables into Serverless

Storing config in the environment is one of the factors in The Twelve-Factor App. We do not want to store our environment variables in our code.

Normally the environment variables is stored in a file called .env in the root of the application and this file should be added to .gitignore so that no one can see the values. You may leave a file called .env.sample to let other team members to know what keys should be included.

Each line is composed in KEY=VALUE format. Blank lines and lines beginning with # are ignored.

Example:

AWS_REGION=ap-east-1

In order to load the environment variables so that the Lambda function can run successfully , we need to use serverless-dotenv-plugin to do so.

To install it, simply run

npm i -D serverless-dotenv-plugin

Then, add the following in your serverless.yml

plugins:
  - serverless-dotenv-plugin

Now you can include your environment variables in your serverless config by referencing them as ${env:VAR_NAME}.

region: ${env:AWS_REGION}

These variables are also injected into lambda functions so that you can reference them as process.env.SOMETHING.