Chapter 37: Terraform Import Moved and Removed Blocks
Chala mitrano, aaj refactor aani adopt. Console madhe aadhi banavleli vastu Terraform madhe ghyaychi tar import. Naav badlaycha tar moved, destroy na karta. Aani dusrya team la dyaychi tar removed. Teenhi code madhe, review sobat.
What you will learn in this chapter
- Adopt console-built resources with import blocks
- Generate draft config with -generate-config-out
- Rename and move into modules with moved
- Hand off resources safely with removed
Concepts in this chapter
- 37.1import block — adopt a resource built by hand
- 37.2moved block — rename without destroy
- 37.3removed block — stop managing without deleting
The chapter recap is at the end of the last concept page.
Practice Tasks
Suppose we are on the DevOps team at Apollo Hospitals, the healthcare company, working from Chennai. Dr. Meena Raman leads the team, and we look after the patient appointment app. Costs are counted in INR. In the tasks below we do real DevOps jobs on this project using what this lesson teaches. Apollo Hospitals is a real company, but this project, the people, servers, IP addresses and numbers are made up for practice.
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Easy S3 bucket resource
Why: Buckets in code are reviewed and never forgotten.
What to do: Write a resource aws_s3_bucket named logs with bucket = "apollo-logs" and tags { Team = "devops" }.
- Write the block type (resource, variable, output, module...) and its labels in quotes.
- Open { and write each argument as name = value.
- Put text values in double quotes; numbers and true/false without quotes.
- Close every block with } and click Check answer.
Easy Output a value
Why: Outputs hand values to scripts and other modules.
What to do: Write output "web_ip" with value = aws_instance.web.public_ip.
- Write the block type (resource, variable, output, module...) and its labels in quotes.
- Open { and write each argument as name = value.
- Put text values in double quotes; numbers and true/false without quotes.
- Close every block with } and click Check answer.
Easy Provider block
Why: The provider tells Terraform which cloud and region to talk to.
What to do: Write a provider "aws" block with region = "ap-south-1".
- Write the block type (resource, variable, output, module...) and its labels in quotes.
- Open { and write each argument as name = value.
- Put text values in double quotes; numbers and true/false without quotes.
- Close every block with } and click Check answer.
Easy Name the practice
Why: IaC is the base of repeatable cloud setups.
What to do: Apollo Hospitals describes its servers, networks and databases in text files kept in Git and creates them with a tool. What is this called (three-letter short form)?
- Write down the facts or numbers the task gives you.
- Work it out step by step.
- Type only the final answer (one word or number) in the box.
- Click Check answer.
Medium EC2 instance using a variable
Why: Referencing var.* avoids hard-coding sizes.
What to do: Write resource aws_instance "web" with ami = "ami-0abcdef1234567890", instance_type = var.instance_type and tags Name = "patient-appointment".
- Write the block type (resource, variable, output, module...) and its labels in quotes.
- Open { and write each argument as name = value.
- Put text values in double quotes; numbers and true/false without quotes.
- Close every block with } and click Check answer.
Medium List resources in state
Why: state list shows what Terraform thinks it manages.
What to do: List every resource address in the state.
- Read the task and pick the tool it needs (git, docker, kubectl, terraform, ansible...).
- Write the tool name, then the sub-command (the action word).
- Add the flags the task needs, each followed by its value.
- Add names, files or paths at the end, then click Check answer.
Medium Pin the provider version
Why: Pinning stops a new provider release from breaking your plan.
What to do: Write a terraform block with required_providers aws = { source = "hashicorp/aws", version = "~> 5.0" }.
- Write the block type (resource, variable, output, module...) and its labels in quotes.
- Open { and write each argument as name = value.
- Put text values in double quotes; numbers and true/false without quotes.
- Close every block with } and click Check answer.
Hard Remote state in S3
Why: Shared remote state with locking stops two people breaking each other.
What to do: Write a terraform block with backend "s3": bucket = "apollo-tfstate", key = "prod/terraform.tfstate", region = "ap-south-1", dynamodb_table = "tf-lock".
- Write the block type (resource, variable, output, module...) and its labels in quotes.
- Open { and write each argument as name = value.
- Put text values in double quotes; numbers and true/false without quotes.
- Close every block with } and click Check answer.
Hard Create several copies with count
Why: count builds N identical resources from one block.
What to do: Write resource aws_instance "worker" with count = 3, ami = "ami-0abcdef1234567890", instance_type = "t3.small" and tags Name = "worker-${count.index}".
- Write the block type (resource, variable, output, module...) and its labels in quotes.
- Open { and write each argument as name = value.
- Put text values in double quotes; numbers and true/false without quotes.
- Close every block with } and click Check answer.
Hard Security group for HTTPS
Why: Opening only 443 keeps the attack surface small.
What to do: Write resource aws_security_group "web" with name = "web-sg" and one ingress block: from_port = 443, to_port = 443, protocol = "tcp", cidr_blocks = ["0.0.0.0/0"].
- Write the block type (resource, variable, output, module...) and its labels in quotes.
- Open { and write each argument as name = value.
- Put text values in double quotes; numbers and true/false without quotes.
- Close every block with } and click Check answer.
Hard Import an existing bucket
Why: Import brings hand-made resources under code control.
What to do: Import the existing S3 bucket apollo-logs into the address aws_s3_bucket.logs.
- Read the task and pick the tool it needs (git, docker, kubectl, terraform, ansible...).
- Write the tool name, then the sub-command (the action word).
- Add the flags the task needs, each followed by its value.
- Add names, files or paths at the end, then click Check answer.
Hard Call a module
Why: Modules package a tested pattern, like a VPC, for reuse.
What to do: Write module "vpc" with source = "terraform-aws-modules/vpc/aws", version = "5.8.1", name = "apollo-vpc" and cidr = "10.0.0.0/16".
- Write the block type (resource, variable, output, module...) and its labels in quotes.
- Open { and write each argument as name = value.
- Put text values in double quotes; numbers and true/false without quotes.
- Close every block with } and click Check answer.
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