Glossary

Term	Definition
IaC (Infrastructure as Code)	Managing and provisioning infrastructure through code files rather than manual processes. Terraform and CloudFormation are IaC tools.
Terraform	An open-source IaC tool by HashiCorp. Uses HCL (HashiCorp Configuration Language). The primary tool of this internship.
CloudFormation	AWS's native IaC service. Uses YAML or JSON templates. Managed directly by AWS.
Provider	A Terraform plugin that manages a specific platform (e.g., the AWS provider). Defined in required_providers.
Resource	A single piece of infrastructure managed by Terraform (e.g., aws_vpc, aws_instance).
State	Terraform's record of what it manages. Stored in terraform.tfstate. Never edit manually.
Module	A reusable, self-contained collection of Terraform resources with its own variables and outputs.
Plan	terraform plan — shows what Terraform will create, change, or destroy before it does anything.
Apply	terraform apply — executes the plan and provisions resources.
Destroy	terraform destroy — removes all resources managed by the current Terraform state.
VPC	Virtual Private Cloud. Your isolated network on AWS. Contains subnets, route tables, and gateways.
Subnet	A range of IP addresses within a VPC. Public subnets have a route to the Internet Gateway. Private subnets do not.
Security Group	A virtual firewall controlling inbound and outbound traffic for AWS resources. Stateful — allow rules only.
IGW (Internet Gateway)	Allows resources in public subnets to communicate with the internet.
ALB (Application Load Balancer)	Distributes HTTP/HTTPS traffic across multiple targets. Layer 7.
ASG (Auto Scaling Group)	Automatically adjusts the number of EC2 instances based on demand. Uses a launch template.
Launch Template	Defines the EC2 configuration (AMI, instance type, key pair, SG) used by an ASG.
RDS	Relational Database Service. Managed database on AWS. Multi-AZ means a standby replica in another AZ.
S3	Simple Storage Service. Object storage. Highly durable and scalable.
IAM	Identity and Access Management. Controls who can do what on AWS.
Least-Privilege	Security principle: grant only the minimum permissions needed, nothing more.
Multi-AZ	Deploying resources across multiple Availability Zones for fault tolerance and high availability.
Jump Host (Bastion Host)	A hardened EC2 instance in a public subnet used as a gateway to access resources in private subnets via SSH.
Docker	A platform for building and running containers. Packages an application and its dependencies into a portable image.
Kubernetes (K8s)	A container orchestration platform. Manages deployment, scaling, and networking of containers.
CI/CD	Continuous Integration / Continuous Deployment. Automated pipeline that builds, tests, and deploys code on every push.
GitLab CI/CD	GitLab's built-in CI/CD system. Configured via a .gitlab-ci.yml file in the repository root.
Pipeline	A sequence of automated stages (validate, build, deploy) triggered by a Git event.