Import block syntax (Terraform 1.5+) - Step-by-Step Execution

Process Flow - Import block syntax (Terraform 1.5+)

Write import block

↓

Run terraform apply

↓

Terraform reads import block

↓

Terraform imports resource state

↓

Resource state linked to config

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Terraform plan shows no changes

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Done

The import block tells Terraform to link existing resources to the config during apply, so state is updated without manual CLI import.

Execution Sample

Terraform

import {
  id = "resource-id"
  to = aws_s3_bucket.example
}

This import block links an existing AWS S3 bucket with id 'resource-id' to the Terraform resource aws_s3_bucket.example.

Process Table

Step	Action	Input	Terraform Behavior	Result
1	Read import block	import { id = "resource-id" to = aws_s3_bucket.example }	Terraform parses import block	Import info stored for apply
2	terraform apply starts		Terraform prepares to import resource	Ready to import resource state
3	Import resource state	id = resource-id	Terraform fetches existing resource state	State linked to aws_s3_bucket.example
4	Update state file		Terraform updates local state with imported resource	State file now includes resource
5	Plan after import		Terraform compares config and state	No changes detected
6	Apply completes		Terraform finishes without creating or destroying	Resource managed by Terraform now
7	Exit	No more steps	Import process complete	Terraform state and config synced

💡 Import block processed, resource state linked, no further changes needed.

Status Tracker

Variable	Start	After Step 3	After Step 4	Final
import_block	Not read	Parsed with id and to	Used to fetch resource state	Processed and cleared
terraform_state	Empty for resource	Resource state fetched	State file updated	State synced with config

Key Moments - 3 Insights

Why doesn't Terraform create a new resource when using the import block?

Because the import block tells Terraform to link an existing resource by its ID, so Terraform updates the state instead of creating a new resource. See execution_table step 3 and 4.

What happens if the resource ID in the import block is incorrect?

Terraform will fail to fetch the resource state during apply (step 3), causing an error and stopping the import process.

Does the import block change the Terraform configuration files?

No, the import block only affects state linking during apply. The configuration remains the same. This is shown in step 5 where plan shows no changes.

Visual Quiz - 3 Questions

Look at the execution_table, at which step does Terraform link the existing resource state to the configuration?

A Step 2

B Step 3

C Step 5

D Step 6

💡 Hint

Check the 'Terraform Behavior' column for when resource state is fetched and linked.

According to variable_tracker, what is the state of terraform_state after step 4?

A Empty for resource

B Resource state fetched

C State file updated

D State synced with config

💡 Hint

Look at the 'terraform_state' row and the 'After Step 4' column.

If the import block is missing the 'to' attribute, what would happen during execution?

A Terraform would fail to parse the import block

B Terraform would import the resource anyway

C Terraform would create a new resource

D Terraform would skip the import silently

💡 Hint

Refer to execution_table step 1 where Terraform parses the import block.

Concept Snapshot

Import block syntax (Terraform 1.5+):
import {
  id = "resource-id"
  to = resource_type.resource_name
}
Use in config to link existing resources during terraform apply.
No manual CLI import needed.
Terraform updates state to manage resource without recreating.

Full Transcript

The import block in Terraform 1.5+ allows you to link existing cloud resources to your Terraform configuration automatically during terraform apply. You write an import block specifying the resource ID and the resource address in your config. When you run terraform apply, Terraform reads this block, fetches the existing resource state, and updates the local state file. This means Terraform now manages the resource without creating or destroying it. The plan after import shows no changes, confirming the resource is linked. If the import block is incorrect or missing required fields, Terraform will fail during parsing or import. This feature simplifies managing existing infrastructure by avoiding manual CLI import commands.