Environment variables in AWS deployments are dynamic key-value pairs that allow developers to configure application behavior at runtime rather than hardcoding values in source code. They provide a flexible and secure way to manage configuration across different deployment stages such as development…Environment variables in AWS deployments are dynamic key-value pairs that allow developers to configure application behavior at runtime rather than hardcoding values in source code. They provide a flexible and secure way to manage configuration across different deployment stages such as development, staging, and production.
In AWS Lambda, environment variables can be defined through the AWS Console, CLI, or Infrastructure as Code tools like CloudFormation and SAM. These variables are encrypted at rest using AWS KMS and can store database connection strings, API keys, feature flags, and other configuration data. Lambda functions access these variables through standard language-specific methods like process.env in Node.js or os.environ in Python.
AWS Elastic Beanstalk supports environment variables through its configuration settings. Developers can set them via the console under Configuration > Software or through .ebextensions configuration files. These variables persist across deployments and instance replacements, making them ideal for storing application-specific settings.
For containerized applications on ECS and EKS, environment variables can be defined in task definitions or pod specifications. Sensitive values should be stored in AWS Secrets Manager or Systems Manager Parameter Store and referenced securely rather than hardcoded in definitions.
Best practices for using environment variables include never committing sensitive values to version control, using different variable sets for each environment, and leveraging AWS services like Parameter Store for centralized configuration management. Variables should follow consistent naming conventions using uppercase letters and underscores.
When deploying with AWS CodeDeploy or CodePipeline, environment variables can be passed through buildspec files or pipeline configurations. This enables dynamic configuration during the CI/CD process, allowing the same codebase to behave differently based on the target environment.
Environment variables are essential for maintaining twelve-factor app principles, promoting separation of configuration from code, and enabling seamless deployments across multiple environments.
Environment Variables in Deployments - AWS Developer Associate Guide
What Are Environment Variables in Deployments?
Environment variables are dynamic key-value pairs that configure application behavior at runtime. In AWS deployments, they allow you to separate configuration from code, enabling the same application to run differently across development, staging, and production environments.
Why Are Environment Variables Important?
• Security: Sensitive data like API keys, database credentials, and secrets can be stored outside your codebase • Flexibility: Change application behavior by modifying variables rather than redeploying code • Portability: Same code artifact can be deployed across multiple environments • Compliance: Follows the twelve-factor app methodology for cloud-native applications
How Environment Variables Work in AWS Services
AWS Lambda: • Configure environment variables in the Lambda console or through CloudFormation/SAM templates • Variables are encrypted at rest using AWS KMS • Maximum size of 4KB for all environment variables combined • Access via process.env (Node.js), os.environ (Python), or System.getenv (Java)
Elastic Beanstalk: • Set through the console, CLI, or .ebextensions configuration files • Variables persist across deployments and environment rebuilds • Can be modified through environment configuration updates
Amazon ECS/Fargate: • Defined in task definitions • Can reference AWS Secrets Manager or Systems Manager Parameter Store • Supports valueFrom for secure secret injection
AWS CodeBuild: • Define in buildspec.yml or project configuration • Can use Parameter Store or Secrets Manager for sensitive values • Built-in environment variables provide build context information
Best Practices
• Never hardcode sensitive values in application code • Use AWS Secrets Manager for rotating credentials • Use Systems Manager Parameter Store for configuration data • Encrypt sensitive environment variables using KMS customer managed keys • Implement least privilege access to environment variable values
Exam Tips: Answering Questions on Environment Variables in Deployments
Key Scenarios to Recognize:
1. Storing database credentials: Look for answers involving Secrets Manager or encrypted environment variables, not plaintext configuration files
2. Lambda configuration: Remember the 4KB limit for environment variables and that they are encrypted at rest by default
3. Cross-environment deployments: Environment variables enable promoting the same code artifact through different stages
4. ECS secrets: The valueFrom field in task definitions references Secrets Manager or Parameter Store
5. CodeBuild sensitive data: Use SECRETS_MANAGER or PARAMETER_STORE environment variable types instead of PLAINTEXT
Common Exam Traps:
• Storing secrets in source code or S3 buckets is incorrect for security-focused questions • Environment variables in Lambda are encrypted at rest by AWS-managed keys by default, but you can use customer managed keys for additional control • Parameter Store standard parameters are free; Secrets Manager charges per secret but offers automatic rotation
Remember These Service Limits:
• Lambda: 4KB total for all environment variables • Elastic Beanstalk: No hard limit, but practical limits apply • ECS: Part of the 64KB task definition limit
Sample Question Pattern:
When asked about securely passing database credentials to a Lambda function, prefer answers that mention: • Secrets Manager with Lambda extension • Encrypted environment variables with KMS • Parameter Store SecureString parameters
Avoid answers suggesting embedding credentials in deployment packages or using unencrypted configuration files.