Note_Tech

All technological notes.

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Terraform - Backend

Back

• Terraform - Backend
  • Backend
    • Defautl Backend
    • Remote Backend
    • Partial configuration for Backend: terraform init -backend-config
  • Lab: S3 as backend
    • Specify variables using a config file
    • Specify variables using Cli
    • Refer to the existing remote backend

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Backend

• backend
  • determines where the terraform.tfstate file is stored and how state locking is handled.

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Defautl Backend

• Default backend:
  • local: stores state as a local file on disk.

terraform {
  backend "local" {}
}

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Remote Backend

• remote backend
  • a configured, shared location for storing the terraform.tfstate file
  • a centralized, secure, and durable remote service
    • e.g., AWS S3, Azure Blob Storage, HCP Terraform.
• Benefits:
  • Collaboration:
    • Multiple team members can work on the same infrastructure, ensuring everyone uses the latest state.
  • State Locking:
    • Prevents concurrent modifications that could corrupt the state file.
  • Security & Persistence:
    • Stores state files away from local machines, often with encryption at rest.
  • Version Control:
    • Facilitates tracking changes over time and rolling back in case of failures.
• Common backend types:
  • Local Storage: The default backend for Terraform, where the state file is stored and managed in the local machine that runs Terraform
  • AWS S3 Bucket: The state file is stored and managed in an AWS S3 bucket.
  • Azure Blob Storage:The state file is stored and managed in Azure Blob Storage.
  • Google Cloud Storage bucket: The state file is stored and managed in a Google Cloud Storage bucket.
  • Remote:Stores state snapshots and executes Terraform CLI operations for HCP Terraform or supported Terraform CI/CD platform, like Spacelift
  • Http: Stores and manage state files in a server by fetching via GET, updating via POST, and deleting with DELETE.
• S3 example

terraform {
  backend "s3" {
    bucket = ""
    key = ""
    region = ""
  }
}

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Partial configuration for Backend: terraform init -backend-config

• Partial configuration
  • When some or all of the arguments are omitted.
  • can be used to refer to different backend configuration
• 3 ways to pass configurations
  • interactive way, tf will ask
  • key/value pairs
  • a file

# key/value pairs
terraform init -backend-config="bucket=mybucket" \
  -backend-config="key=mykey"
  -backend-config="region=myregion"

# for dev
terraform init -backend-config=dev.config
# for test
terraform init -backend-config=test.config
# for prod
terraform init -backend-config=prod.config

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Lab: S3 as backend

• provider.tf

terraform {
  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = "~> 5.0"
    }
  }

  # Configuring a remote backend
  backend "s3" {
    bucket = ""
    region = ""
    key    = ""
    dynamodb_table  = ""    # backend lock in dynamodb
  }
}

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Specify variables using a config file

• state.config

# state.config
bucket = "your-bucket"
key    = "your-state.tfstate"
region = "eu-central-1"
profile= "Your_Profile"

• init with config file

`terraform init -backend-config="./state.config"`

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Specify variables using Cli

• if not using state.config, can use Command-line key/value pairs

# cli
terraform init \
    -backend-config="address=demo.consul.io" \
    -backend-config="path=example_app/terraform_state" \
    -backend-config="scheme=https"

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Refer to the existing remote backend

data "terraform_remote_state" "network" {
  backend = "s3"
  config = {
    bucket = "terraform-state-prod"
    key    = "network/terraform.tfstate"
    region = "us-east-1"
  }
}