Terraform plan for preview - Step-by-Step Execution

Process Flow - Terraform plan for preview

Write Terraform config

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Run 'terraform init'

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Run 'terraform plan'

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Terraform reads current state

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Terraform compares desired vs current

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Show planned changes

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User reviews plan

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Decide to apply or modify config

Terraform plan reads your config and current state, then shows what changes it will make without applying them.

Execution Sample

Terraform

terraform init
terraform plan

Initialize Terraform and preview the infrastructure changes without applying them.

Process Table

Step	Action	Evaluation	Result
1	Run 'terraform init'	Initialize backend and providers	Backend and providers ready
2	Run 'terraform plan'	Read current state	Current state loaded
3	Compare desired config with current state	Detect differences	Plan created with changes
4	Show plan output	Display actions (add, change, destroy)	User sees what will happen
5	User reviews plan	Decide next step	Plan accepted or config changed
6	Exit	No changes applied yet	Preview complete

💡 Plan shows changes but does not apply them; user must run 'terraform apply' to make changes.

Status Tracker

Variable	Start	After init	After plan	Final
terraform state	empty	initialized	loaded current state	unchanged (preview only)
plan output	none	none	generated with changes	displayed to user

Key Moments - 3 Insights

Why does 'terraform plan' not change any real infrastructure?

'terraform plan' only shows what would happen; it reads state and config but does not apply changes, as shown in execution_table step 6.

What does Terraform compare during 'plan'?

It compares the desired config with the current state to find differences, as seen in execution_table step 3.

Why must we run 'terraform init' before 'terraform plan'?

'terraform init' sets up providers and backend needed to read state and config, enabling 'plan' to work correctly (execution_table step 1).

Visual Quiz - 3 Questions

Look at the execution_table, what is the result after running 'terraform init'?

A Backend and providers ready

B Plan created with changes

C Current state loaded

D No changes applied yet

💡 Hint

Check execution_table row 1 under Result column.

At which step does Terraform compare desired config with current state?

A Step 2

B Step 3

C Step 4

D Step 5

💡 Hint

Look at execution_table rows and find where comparison happens.

If you skip 'terraform init', what will likely happen when running 'terraform plan'?

A Plan will show changes correctly

B Plan will apply changes automatically

C Plan will fail due to missing backend/providers

D Plan will ignore current state

💡 Hint

Refer to key_moments about why 'terraform init' is needed before 'plan'.

Concept Snapshot

terraform init: prepares backend and providers
terraform plan: previews changes without applying
Reads current state and compares with config
Shows add/change/destroy actions
No real changes until 'terraform apply' runs

Full Transcript

Terraform plan is a command that lets you see what changes Terraform will make to your cloud infrastructure before actually making them. First, you run 'terraform init' to set up the environment. Then, 'terraform plan' reads the current state and compares it with your desired configuration. It shows a list of changes it will perform, like adding or removing resources. This preview helps you avoid surprises. No real changes happen until you run 'terraform apply'.