*It is established standards not to put secrets in codebases because of security. Usually the secrets are introduced to
during deployment or code execution.

For Serverless Framework, it is no different. To introduce environment variable at deployment through the serverless.yml file,
use the environment key under provider key. *

...

provider:
  name: aws
  runtime: nodejs14.x
  environment:
    PERSON: tope
    STORE_KEY_ID: 34444

...

In code, you should be able to get the PERSON and STORE_KEY_ID environment variable as

const {PERSON, STORE_KEY_ID} = process.env

But there is still a security issue here, the serverless.yml is stll in your repository and anyone can have access to the value
just by checking the serverless.yml file.

I would like to look at 2 ways, this problem can be solved.

1. Introducing the environment variables into the environment where the deployment process for the serverless application happens and letting the serverless.yml reference those values.

...

provider:
  name: aws
  runtime: nodejs14.x
  environment:
    PERSON: ${env.PERSON}
    STORE_KEY_ID: ${env.STORE_KEY_ID}

...

The question of having the environment variables in the environment depends on the environment. Usually most CI platforms like Github Actions
have ways for you to sepcify the secrets you want interjected into your CI environment. For Github Actions, these are called Action Secrets and
you can find more in the video link https://www.youtube.com/watch?v=3bz0IR-GDIw .

What i want to focus on now is how to introduce these variables into the environment locally. It turns out Serverless framework can read
from a .env file without any 3rd party plugin. All you just need to do is

• Add a .env to you folder, same level as your serverless.yml file with content

PERSON=tope
STORE_KEY_ID=1234

• Add key useDotenv to the your serverless.yml file. This causes serverless to load environmental variables automatically from .env.

...

useDotenv: true

provider:
  name: aws
  runtime: nodejs14.x
  environment:
    PERSON: ${env.PERSON}
    STORE_KEY_ID: ${env.STORE_KEY_ID}

...

NOTE: this not make it automatically appear in your code, you still need to pass each of the environment to one in the environment key under provider.
Don't forget to add your .env to your .gitignore file to prevent the file from being pushed to your central repository.

1. By passing in variables as serverless parameters from the Serverless Dashboard. Serverless Dashboard helps you store secrets that can be used accross different team members. Generally use the .env file for local development and testing and use the secrets in Serverless dashbord for deployment in your CI.

This is not an arcticle on Serverless Dashboard but let me show you where it seats in the serverless deployment process.
The first time I used serverless framework , it was basically like this

[serverless framework on machine] ====== deploy ====>  [AWS]

All AWS secrets and other secrets are introduced during deployment from the machine. This machine genrally was your local device.

Now it is like this

[serverless framework on machine]  =====> [Serverless Cloud] ====== deploy ====>  [AWS]

All AWS secrets and other secrets are introduced during deployment from the Serverless Cloud. This adds security and removes the risk of
anyone jsut being able to deploy since there are security access check between any machine and the Serverless Cloud.

The Serverless Dashboard is the dashboard for the Serverless Cloud. One of the things is does is the ability to store secrets as parameters.
To access to parameters in your serverless.yml is shown below

...

provider:
  name: aws
  runtime: nodejs14.x
  environment:
    PERSON: ${param.PERSON}
    STORE_KEY_ID: ${param.STORE_KEY_ID}

...

So how do you write your serverless.yml so it can work with both .env locally and parameters when going through the Serverless Cloud?
Serverless framework gives us an easy way to do that

...

useDotenv: true

provider:
  name: aws
  runtime: nodejs14.x
  environment:
    PERSON: ${param.PERSON, env.PERSON}
    STORE_KEY_ID: ${param.STORE_KEY_ID, env.STORE_KEY_ID}

...

It checks for param.PERSON and falls back to env.PERSON. This helps make our serverless.yml very flexible.
For some properties, this can be extended

PERSON: ${param.ENV, env.ENV, 'dev'}

NOTE, do not use this for sensitive information, check only the param and the .env file.

Please reach out with any questions or clarifications you need.