How to Set Environment Variable in AWS Lambda ?

AWS Lambda is a managed serverless deployment service of AWS that can be used for the implementation of various applications in the cloud. AWS lambda may use various environment variables for the execution of different operations. eg. Database Credentials, API Keys .etc. There are various ways we can set these variables in AWS lambda. let's understand how we can set environment variables in AWS lambda.

What is AWS Lambda?

AWS Lambda Functions are serverless components that execute code only when the particular trigger is invoked. the trigger for functions has to be configured as required. various triggers such as HTTP, S3 object upload, message queues are supported by AWS Lambda. AWS Lambda reduces the cost of idle infrastructure.

Understanding Of Primary Terminologies

• AWS Lambda Function: It is a serverless compute component that allows the execution of code only when invoked without the provision of servers.
• Function Trigger: It is an event that invokes a lambda function and executes it. E.g. HTTP Trigger, Message queues etc.
• Lambda handler: It is a function that accepts events that invoke the lambda function and executes code mentioned in the function.
• Environment Variables : These are properties that are used by the lambda function to perform one or more tasks in the function.

Setting Environment Variables in AWS Lambda

1. Setting AWS Lambda Environment Variables via Management Console.

• Create and set a lambda function with the preferred configuration. Once the function is created go to the overview page of the function.
• On this page scroll to view function options like below.

• Click on the configuration tab and from the left pane select environment variables. Click on add.
• Specify key and value for the environment variables and click save. The environment variables will be set for the function.

2. Configuring AWS Lambda Environment Variables Using AWS CLI.

• If you are using AWS CLI then we can easily set environment variables using below command.
• Once the function is created you can update the function with environment variables using below command.

aws lambda update-function-configuration --function-name <NAME-OF-FUNCTION> --environment Variables={KEY1=VALUE1,KEY2=VALUE2}

• In the above command specify the function name in place of <NAME-OF-FUNCTION>.
• Add your environment variables as key=value in the end. Once done run the command the function will be updated with the environment variables.

3. Configuring AWS Lambda Environment Variables Using IAAC script.

• For this article lets see how we can add environment variables in terraform script for creating lambda function.
• In the terraform file add environment variables as below after the configuration of lambda function.

environment {
    variables = {
      KEY1 = "VALUE1"
      KEY2 = "VALUE2"
    } 
}

• The entire script for lambda function will look like below

resource "aws_lambda_function" <RESOURCE_NAME> {
  function_name = <YOUR_LAMBDA_FUNCTION_NAME>
  handler       = "lambda_function.handler"
  runtime       = "nodejs14.x"
  role          = aws_iam_role.iam_for_lambda.arn

  environment {
    variables = {
      KEY1 = "VALUE1"
      KEY2 = "VALUE2"
    }
  }
}

• Replace Resource name and function name in above script along with environment variables specified as json below.
• Once done Run the script and function will be created.

terraform apply

• The environment variables will also be added to the function.

Conclusion

Thus, we have seen different ways to set environment variables in Lambda . Using AWS console is the most common way to setup environment variables in lambda. For Infrastructure as a Code setting variables in IAAC code script is the best option.