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Providers - Dependency Lock File

Step-01: Introduction

  • Understand the importance of Dependency Lock File which is introduced in Terraform v0.14

Step-02: Review the Terraform Manifests

  • c1-versions.tf
  • Discuss about Terraform, AWS and Random Pet Provider Versions
  • c2-s3bucket.tf
  • Discuss about Random Pet Resource
  • Discuss about S3 Bucket Resource
  • .terraform.lock.hcl
  • Discuss about Provider Version, Version Constraints and Hashes

Step-03: Initialize and apply the configuration

# Initialize Terraform
terraform init

# Validate Terraform Configuration files
terraform validate

# Execute Terraform Plan
terraform plan

# Create Resources using Terraform Apply
terraform apply
  • Review .terraform.lock.hcl
  • Discuss about versions
  • Compare .terraform.lock.hcl-ORIGINAL & .terraform.lock.hcl
  • Backup .terraform.lock.hcl as .terraform.lock.hcl-FIRST-INIT 
# Backup
cp .terraform.lock.hcl .terraform.lock.hcl-FIRST-INIT

Step-04: Upgrade the AWS provider version

  • For AWS Provider, with version constraint version = ">= 2.0.0", it is going to upgrade to latest 3.x.x version with command terraform init -upgrade 
# Upgrade Provider Version
terraform init -upgrade
  • Review .terraform.lock.hcl
  • Discuss about AWS Versions
  • Compare .terraform.lock.hcl-FIRST-INIT & .terraform.lock.hcl

Step-05: Apply Terraform configuration with latest AWS Provider

  • Should fail due to S3 related latest changes came in AWS v3.x provider when compared to AWS v2.x provider
# Terraform Apply
terraform apply

Step-06: Comment region in S3 Resource and try Terraform Apply

  • It should work.
  • When we do a major version upgrade to providers, it might break few features.
  • So with .terraform.lock.hcl, we can avoid this type of issues.
# Comment Region Attribute
# Resource Block: Create AWS S3 Bucket
resource "aws_s3_bucket" "sample" {
  bucket = random_pet.petname.id
  acl    = "public-read"

  #region = "us-west-2"
}

# Terraform Apply
terraform apply

Step-07: Clean-Up

# Destroy Resources
terraform destroy

# Delete Terraform Files
rm -rf .terraform    # We are not removing files named ".terraform.lock.hcl, .terraform.lock.hcl-ORIGINAL" which are needed for this demo for you.
rm -rf terraform.tfstate*

References