Infrastructure as Code Engineer Interview Questions

IaC Benefits:

• Consistency: Eliminate configuration drift and manual errors
• Version Control: Track changes and enable rollbacks
• Automation: Faster, repeatable deployments
• Documentation: Self-documenting infrastructure
• Cost Management: Better resource tracking and optimization

Infrastructure Approaches:

• Mutable: Update existing infrastructure in place
• Immutable: Replace entire infrastructure components
• Configuration Drift: Mutable prone to drift, immutable prevents it
• Rollback: Immutable enables easier rollbacks
• Testing: Immutable provides better testing consistency

Terraform State:

• State Tracking: Maps configuration to real-world resources
• Performance: Caches resource attributes for faster operations
• Metadata: Stores resource dependencies and relationships
• Remote State: Enables team collaboration and locking
• Sensitive Data: May contain secrets, requires secure storage

Secret Management Strategies:

• External Systems: HashiCorp Vault, AWS Secrets Manager
• Environment Variables: Pass secrets via TF_VAR_* variables
• Data Sources: Fetch secrets at runtime
• State Encryption: Encrypt state files at rest
• Sensitive Flag: Mark variables as sensitive

Module Best Practices:

• Single Responsibility: One module, one purpose
• Versioning: Use semantic versioning for modules
• Documentation: Clear README and variable descriptions
• Testing: Unit and integration tests
• Composition: Build complex infrastructure from simple modules

Environment Strategies:

• Workspace Separation: Use Terraform workspaces
• Directory Structure: Separate directories per environment
• Variable Files: Environment-specific .tfvars files
• Remote State: Separate state files per environment
• Module Composition: Reuse modules across environments

IaC CI/CD Pipeline:

• Validation: Syntax checking and linting
• Planning: Generate and review execution plans
• Testing: Unit tests and compliance checks
• Approval: Manual approval gates for production
• Deployment: Automated apply with monitoring

Testing Approaches:

• Static Analysis: Linting and security scanning
• Unit Testing: Test individual modules
• Integration Testing: Test complete environments
• Compliance Testing: Policy and security validation
• Smoke Testing: Basic functionality verification

Tool Comparison:

• Multi-cloud: Terraform supports multiple providers
• AWS Integration: CloudFormation deeply integrated with AWS
• State Management: Terraform explicit, CloudFormation implicit
• Language: HCL vs JSON/YAML
• Community: Terraform larger open-source community

Stack Management:

• Cross-Stack References: Export/Import values between stacks
• Nested Stacks: Modular stack composition
• Stack Sets: Deploy across multiple accounts/regions
• Dependencies: Implicit dependencies via references
• Rollback: Automatic rollback on failure

Tool Selection:

• Terraform: Infrastructure provisioning and management
• Ansible: Configuration management and application deployment
• Complementary: Often used together in workflows
• Agentless: Both are agentless tools
• Use Cases: Terraform for infra, Ansible for config

Drift Management:

• Detection: Regular plan runs to identify changes
• Prevention: Restrict manual changes via policies
• Correction: Automated drift remediation
• Monitoring: Continuous compliance checking
• Immutable Infrastructure: Replace rather than modify