Terraform

Overview

• terraform config
• providers
• resources
• terraform state
• variables
• init -> validate -> plan -> apply -> destroy

links

• tutorials:
  • https://developer.hashicorp.com/terraform/intro
  • https://developer.hashicorp.com/terraform/tutorials/aws-get-started/infrastructure-as-code
  • https://developer.hashicorp.com/terraform/tutorials/aws-get-started/aws-create
  • https://developer.hashicorp.com/terraform/tutorials/aws-get-started/aws-manage
• vscode extension: https://marketplace.visualstudio.com/items?itemName=HashiCorp.terraform

Reference

• commands:
  • terraform fmt : format code
  • terraform init : init workspace (installs prodiers in terraform dir)
  • terraform apply
  • terraform destroy
  • terraform validate : validate tf files
  • terraform.tf_state
  • terraform state list : list current state
  • terraform show
  • terraform plan: (can use vars with -var)
• blocks:
  • terraform: terraform config
  • provider: provider config
  • data : query cloud provider for information about other resources
  • resource: components of infrastructure
  • module : reusable sets of configuration

• folder structure:

  • terraform.tf : terraform config
  • main.tf: provider blocks and other primary infrastructure in main.tf as a best practice
  • variables.tf : store variable blocks
  • outputs.tf: access terraform config attributes with other automation tools or workflows.

• registry: https://registry.terraform.io/providers/hashicorp/aws/6.22.1/docs?utm_content=documentHover&utm_medium=Visual+Studio+Code&utm_source=terraform-ls

• gitignore: https://developer.hashicorp.com/terraform/language/style#gitignore

IaC with Terraform

• manage infastructure as code instead of from ui
• works on multiple cloud platforms
• terraform states -> track resources with state
• terraform providers -> plugins for each cloud provider.
• combine resources into module

• declarative language: describes end state of infrastructure

• steps:

  • scope
  • author
  • initialize
  • plan
  • apply

• state file to keep track of current state

terraform aws get started

• Configure your provider in terraform.tf
• Configure everything else in main.tf
• Each provider block configures each provider
• data sources to query cloud provdier about more information about resources
• resource block cmoponent of infra -> docs in registration
• resource type + resource_name = resource address
• use resource_type.resource_name. to access resource
• (AMI: amazon machine images)
• variable: parametrize the behavior of your Terraform configuration
• use var. to refer to variables
• modules: reusable collection of resources, module. to refer to module.

adhoc

• Terraform’s model is: > “Desired end state, not live control.”

• You’re thinking:

  “Terraform is how I change infra, so I’ll just change a variable”

  • That instinct is correct for creation, wrong for control.

  • Terraform is:

    • excellent at bring-up

    • terrible at runtime orchestration

  • This is a classic infra vs control-plane split.