Concepts
Environment variables are dynamic values which affect the processes or behavior of running applications on an operating system. They exist outside the application, offering a convenient way to configure application behavior without modifying code.
AWS Services and Environment Variables
In the context of AWS, several services allow you to set and manage environment variables:
AWS Lambda
AWS Lambda allows you to run code without provisioning or managing servers. You can set environment variables for your Lambda functions in the AWS Management Console, the AWS CLI, or by using AWS SDKs.
Example:
When you configure a Lambda function, you can set environment variables like this:
{
“Variables”: {
“ENVIRONMENT”: “prod”,
“DB_CONNECTION_STRING”: “your_connection_string”,
…
}
}
This allows your code to access these variables at runtime:
import os
db_connection_string = os.environ[‘DB_CONNECTION_STRING’]
Amazon EC2
For applications running on EC2 instances, environment variables can be set at the instance level or passed in through user data scripts when the instance is initiated.
Example:
Using EC2 user data to export environment variable:
#!/bin/bash
export DB_HOST=your_database_host
Elastic Beanstalk
Elastic Beanstalk is an easy-to-use service for deploying and scaling web applications. You can specify environment variables for your application environment in the Elastic Beanstalk console, `.ebextensions` configuration files, or using the EB CLI.
Example using `.ebextensions`:
Create a file named `env.config` in the `.ebextensions` directory:
option_settings:
– namespace: aws:elasticbeanstalk:application:environment
option_name: DB_USER
value: your_database_user
– namespace: aws:elasticbeanstalk:application:environment
option_name: DB_PASS
value: your_password
Amazon ECS
When using Amazon Elastic Container Service (ECS), environment variables can be set in task definitions for your containerized applications.
Example of task definition with environment variables:
{
“containerDefinitions”: [
{
“name”: “my-container”,
“image”: “my-container-image”,
“environment”: [
{
“name”: “LOG_LEVEL”,
“value”: “info”
}
]
}
]
}
Best Practices for Using Environment Variables
- Security: Avoid storing sensitive information plaintext in environment variables. Use AWS Secrets Manager or Parameter Store to encrypt sensitive data and then reference the secret or parameter in your environment variable.
- Separation of Environments: Use different sets of environment variables for development, testing, and production to separate your environments and reduce the risk of environment-specific configurations causing failures or breaches.
- Configuration Management: Ensure that your environment variables are version controlled and managed as part of your infrastructure as code practices.
- Automate Deployment: Use CI/CD pipelines to manage the deployment of environment variables, reducing manual errors.
Conclusion
Utilizing environment variables effectively allows AWS developers to create flexible, scalable, and secure applications. As you prepare for the AWS Certified Developer – Associate exam, be sure to understand how to set, reference, and manage environment variables across different AWS services such as AWS Lambda, EC2, Elastic Beanstalk, and ECS. Remember to follow best practices, particularly concerning security and configuration management.
Answer the Questions in Comment Section
True or False: Environment variables are immutable once they have been set in an AWS Lambda function.
Answer: False
Explanation: Environment variables in AWS Lambda functions can be changed using the AWS Management Console, AWS CLI, or SDKs. They are not immutable and can be updated anytime to modify the function’s behavior.
What command would you use to set an environment variable in an EC2 instance?
- A) export VARIABLE_NAME=value
- B) set VARIABLE_NAME=value
- C) aws ec2 set-env VARIABLE_NAME=value
- D) ec2-environment-variables –set VARIABLE_NAME=value
Answer: A) export VARIABLE_NAME=value
Explanation: In a Linux EC2 instance, you would use the ‘export’ command followed by the variable name and value to set an environment variable.
True or False: Environment variables are used to pass operational parameters to your application.
Answer: True
Explanation: Environment variables are a common way to configure operational parameters for applications, allowing for a more secure and flexible configuration management.
Which of the following is NOT a typical use case for environment variables in AWS?
- A) Storing database connection strings
- B) Storing application secrets like API keys
- C) Managing application log levels
- D) Allocating Elastic IP addresses to instances
Answer: D) Allocating Elastic IP addresses to instances
Explanation: Environment variables are used for configuration settings such as database connection strings, API keys, and log levels, not for allocating network resources like Elastic IP addresses.
True or False: AWS Lambda functions automatically have access to environment variables set within the AWS Management Console.
Answer: True
Explanation: Any environment variables set in the AWS Management Console for Lambda functions are accessible within the function’s execution environment without additional configuration.
How can an AWS Lambda function access the value of an environment variable named `DATABASE_URL`?
- A) context.DATABASE_URL
- B) process.env.DATABASE_URL
- C) lambda.getEnvironmentVariable(‘DATABASE_URL’)
- D) getenv(‘DATABASE_URL’)
Answer: B) process.env.DATABASE_URL
Explanation: In Node.js Lambda functions, environment variables are accessed using `process.env.VARIABLE_NAME`. For `DATABASE_URL`, it would be accessed with `process.env.DATABASE_URL`.
True or False: When using AWS Elastic Beanstalk, you can use the Elastic Beanstalk Environment Properties section to define environment variables.
Answer: True
Explanation: When using AWS Elastic Beanstalk, you can define environment variables in the Environment Properties section of the software configuration settings in the Elastic Beanstalk console.
Which AWS service allows you to store environment variables as secure, encrypted strings?
- A) AWS Key Management Service (KMS)
- B) AWS Secrets Manager
- C) AWS Parameter Store
- D) All of the above
Answer: D) All of the above
Explanation: AWS KMS allows you to create and manage keys, AWS Secrets Manager helps manage and retrieve secrets, and AWS Systems Manager Parameter Store provides storage for configuration data management and secrets, all of which can be used to store environment variables in a secure, encrypted form.
True or False: Environment variables in Amazon ECS tasks should be specified within the task definition.
Answer: True
Explanation: Environment variables for containers run by Amazon ECS should be specified in the container definitions section of the task definition.
In AWS CodeBuild, where can you specify environment variables for your build project?
- A) In the buildspec.yml file
- B) AWS CodeBuild console under project settings
- C) Both A and B
- D) As command-line parameters when starting a build
Answer: C) Both A and B
Explanation: In AWS CodeBuild, you can specify environment variables either in the buildspec.yml file under the `env` section or in the CodeBuild console under the Environment section of the project settings.
True or False: Environment variables can be shared between different AWS services without any restrictions.
Answer: False
Explanation: There are security and access controls in place that restrict the uninhibited sharing of environment variables between AWS services. AWS Identity and Access Management (IAM) policies and service-specific access controls regulate how and when environment variables can be shared.
In AWS Lambda, what is the maximum size of environment variables?
- A) 1 KB
- B) 4 KB
- C) 64 KB
- D) 1 MB
Answer: C) 64 KB
Explanation: The total size of all the environment variables associated with a Lambda function cannot exceed 64 KB.
Great information on environment variables for the AWS Certified Developer exam. Very helpful!
Thanks for the post. Can anyone explain how to securely manage environment variables in AWS?
I appreciate the detailed explanation!
What’s the best practice for loading environment variables in a Lambda function?
How do environment variables impact the configuration of ECS tasks?
This post was helpful in understanding the exam topics.
Why is it necessary to use environment variables instead of hardcoded values?
Thanks for the insights. How often should I rotate my environment variables?