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Overview of the Terraform core concepts and workflow

Terraform Core Workflow​

1. Initializition:​

Run terraform init to initialize the working directory containing Terraform configuration files. This create a .terraform directory in the working directory where store Terraform state and plugins.

2. Configuration:​

Create a Terraform configuration file (e.g. main.tf) that defines the infrastructure resources. The configuration file is written in HashiCorp Configuration Language (HCL).

3. Plan:​

Run terraform plan to create an execution plan. This command will show what actions Terraform will take to change the infrastructure to match the configuration.

4. Apply:​

Run terraform apply to apply the changes required to reach the desired state of the configuration. This command will create, update, or delete resources as necessary.

5. Destroy:​

Run terraform destroy to destroy all the resources defined in the configuration file.

Key Concepts​

  1. Provider: A plugin that Terraform uses to interact with the APIs of cloud providers (e.g. AWS, Azure, GCP).

  2. Resource: Individual Cloud objects that Terraform manages (e.g. EC2 instance, S3 bucket).

  3. Module: A container for multiple resources that are used together.

  4. Variable: Parameters that can be passed into modules.

  5. Expression: A reference to a value in Terraform configuration. e.g var.my_var.

  6. State: A record of the current state of the infrastructure managed by Terraform.

  7. Output: Values that are returned by a module.

  8. Workspace: A way to manage multiple states in the same configuration.

  9. Backend: A method for storing Terraform state.

  10. Provisioner: A way to perform tasks on the local machine or on the resource after it is created.

Core Workflow Steps​

  1. Define resources in configuration files. e.g. main.tf.

  2. Initialize the working directory with terraform init.

  3. Create an execution plan with terraform plan.

  4. Review the output and manage the infrastructure.

  5. Apply the changes with terraform apply.

  6. Destroy the resources with terraform destroy.(Optional)