Explanation of the Terraform workflow, outlining the various steps with additional explanations and examples:
Step 1: Initialization (terraform init)
Detailed Explanation:
The init command initializes a working directory containing Terraform configuration files. It downloads the necessary plugins and modules defined in the configuration files. This step is executed before starting to work on a new configuration or when cloning a repository with Terraform files for the first time.
Example:
terraform init
Step 2: Configuration (*.tf files)
Detailed Explanation:
Create or modify .tf files defining the desired infrastructure configuration using HashiCorp Configuration Language (HCL). These files include resource definitions, providers, variables, outputs, and any necessary modules.
Example (main.tf):
provider "aws" {
region = "us-west-2"
}
resource "aws_instance" "example" {
ami = "ami-0c55b159cbfafe1f0"
instance_type = "t2.micro"
}
Step 3: Planning (terraform plan)
Detailed Explanation:
The plan command generates an execution plan. It compares the desired state from the configuration files with the current state, indicating what changes will occur. It provides a detailed view of the additions, modifications, or deletions Terraform will perform.
Example:
terraform plan
Step 4: Applying Changes (terraform apply)
Detailed Explanation:
The apply command executes the planned changes defined in the configuration files. It creates, modifies, or deletes resources as per the generated execution plan. It prompts for confirmation before proceeding with the changes.
Example (with auto-approval):
terraform apply --auto-approve
Step 5: Reviewing State (terraform show, terraform state)
Detailed Explanation:
The show and state commands display the current state of managed infrastructure. show provides a high-level view, while state allows for more advanced state management operations.
Example (terraform show):
terraform show
Step 6: Destroying Resources (terraform destroy)
Detailed Explanation:
The destroy command terminates and removes resources defined in the configuration files. It prompts for confirmation before destroying resources to avoid accidental deletions.
Example (with auto-approval):
terraform destroy --auto-approve
Step 7: Managing State (terraform state)
Detailed Explanation:
The state command provides functionality to manage and inspect the Terraform state. It allows for operations like moving state, removing resources from state, and more.
Example (terraform state list):
terraform state list
By following these steps in the Terraform workflow, users can effectively manage their infrastructure as code, ensuring consistency, predictability, and ease of management within their cloud environments. Each command plays a crucial role in different stages of the infrastructure lifecycle.