7. Terraform Logging

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🔵 Terraform Diff Symbols (VERY IMPORTANT)

Terraform shows diffs like this:

+ create
~ update in-place
- destroy
-/+ replace
<= read (data source)

Let’s break them down:

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✔ + Create

Terraform will create a resource.

Example:

# aws_lambda_function.put will be created
+ resource "aws_lambda_function" "put" {

Meaning:
Resource does NOT exist in AWS → Terraform will create it.

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✔ ~ Update In-Place

Resource exists but needs modification.

~ memory_size: 128 → 256

Meaning:
Terraform will update the resource without deleting it.

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✔ - Destroy

Terraform will delete a resource.

- resource "aws_lambda_function" "old"

Meaning:
Terraform thinks this resource should not exist.

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✔ -/+ Replace

Resource must be destroyed then recreated.

-/+ resource "aws_lambda_function" "example"

Meaning:
Some attributes force replacement, like:

• function name

Terraform will:
1️⃣ destroy
2️⃣ recreate

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✔ <= Read

This is for data sources.

<= data "aws_ami" "latest"

Meaning:
Terraform is reading data (not creating anything).

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🟧 Plan Summary (bottom section)

At the bottom of terraform plan, you always see:

Plan: 3 to add, 1 to change, 0 to destroy

This is your quick summary.

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🧾TF_LOG and TF_LOG_PATH are environment variables used for debugging Terraform.

Example

export TF_LOG=TRACE
export TF_LOG_PATH=/root/terraform-debug.log
terraform apply

TF_LOG Controls how much log detail Terraform prints. Possible values (from least → most detail):

Level	Use
ERROR	Only errors
WARN	Warnings + errors
INFO	General info (default useful debug)
DEBUG	Detailed debugging
TRACE	Maximum verbosity (very detailed)

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