🖥️ Terraform CLI: Comprehensive Usage Guide

1. 🌍 What is Terraform CLI?

Terraform CLI is the command-line interface for Terraform, enabling you to:

Initialize Terraform configurations
Plan infrastructure changes
Apply infrastructure changes
Manage state files
Debug and troubleshoot issues
Automate infrastructure operations

2. 📦 Basic CLI Commands

Step 1: Initialize Terraform

# Initialize a new or existing Terraform configuration
terraform init

# Initialize with specific backend configuration
terraform init -backend-config="backend.tfvars"

# Initialize without backend configuration
terraform init -backend=false

# Reconfigure backend (ignore existing state)
terraform init -reconfigure

# Upgrade modules and providers
terraform init -upgrade

Step 2: Format Configuration

# Format all Terraform files in current directory
terraform fmt

# Format files recursively
terraform fmt -recursive

# Check if files are formatted (CI/CD friendly)
terraform fmt -check

# Display files that would be reformatted
terraform fmt -check -diff

# Format specific files
terraform fmt main.tf variables.tf

Step 3: Validate Configuration

# Validate configuration syntax
terraform validate

# Validate with JSON output
terraform validate -json

# Validate specific directory
terraform validate ./modules/networking

Step 4: Plan Changes

# Generate and show execution plan
terraform plan

# Save plan to file
terraform plan -out=tfplan

# Plan with specific variable file
terraform plan -var-file="prod.tfvars"

# Plan with specific variables
terraform plan -var="instance_type=t3.large"

# Plan without refreshing state
terraform plan -refresh=false

# Plan with detailed exit code (for CI/CD)
terraform plan -detailed-exitcode

# Plan with lock timeout
terraform plan -lock-timeout=5m

# Plan in compact mode
terraform plan -compact

Step 5: Apply Changes

# Apply changes with auto-approval
terraform apply -auto-approve

# Apply saved plan
terraform apply tfplan

# Apply with specific variables
terraform apply -var="environment=prod"

# Apply with variable file
terraform apply -var-file="staging.tfvars"

# Apply without refreshing state
terraform apply -refresh=false

# Apply with lock timeout
terraform apply -lock-timeout=10m

# Apply with parallelism limit
terraform apply -parallelism=2

3. 🔄 State Management Commands

Step 1: View State

# Show all resources in state
terraform state list

# Show detailed state information
terraform show

# Show specific resource in state
terraform show aws_instance.example

# Pull state to file
terraform state pull > terraform.tfstate.backup

# Push state from file
terraform state push terraform.tfstate.backup

Step 2: Move Resources in State

# Move resource within state
terraform state mv aws_instance.old aws_instance.new

# Move resource to module
terraform state mv aws_vpc.main module.networking.aws_vpc.main

# Move resources between modules
terraform state mv module.old.module.aws_instance.example module.new.module.aws_instance.example

# Move with state backup
terraform state mv -state-out=backup.tfstate aws_instance.old aws_instance.new

Step 3: Remove Resources from State

# Remove resource from state (not from infrastructure)
terraform state rm aws_instance.example

# Remove multiple resources
terraform state rm aws_instance.example1 aws_instance.example2

# Remove module from state
terraform state rm module.vpc

Step 4: Import Resources

# Import existing resource into state
terraform import aws_instance.example i-1234567890abcdef0

# Import module resource
terraform import module.vpc.aws_vpc.main vpc-12345678

# Import with provider configuration
terraform import -provider=registry.terraform.io/hashicorp/aws aws_instance.example i-1234567890abcdef0

4. 🏗️ Workspace Commands

Step 1: List Workspaces

# List all workspaces
terraform workspace list

# Show current workspace
terraform workspace show

Step 2: Create and Switch Workspaces

# Create new workspace
terraform workspace new dev

# Switch to existing workspace
terraform workspace select prod

# Delete workspace
terraform workspace delete staging

5. 📊 Output Commands

Step 1: View Outputs

# Show all outputs
terraform output

# Show specific output
terraform output vpc_id

# Show output in JSON format
terraform output -json

# Show output in raw format
terraform output -raw vpc_id

6. 🔧 Provider Commands

Step 1: Provider Operations

# Show installed providers
terraform providers

# Show provider schema
terraform providers schema

# Show provider schema in JSON
terraform providers schema -json

# Lock provider versions
terraform providers lock -platform=linux_amd64 -platform=darwin_amd64

7. 🧪 Test Commands (Terraform 1.6+)

Step 1: Run Tests

# Run all tests
terraform test

# Run tests with verbose output
terraform test -v

# Run specific test file
terraform test tests/main_test.tftest.hcl

# Run tests with filtering
terraform test -filter="test_vpc"

# Run tests without updating state
terraform test -no-color

8. 🐛 Debugging Commands

Step 1: Enable Debug Logging

# Set log level to DEBUG
export TF_LOG=DEBUG

# Set log level to TRACE
export TF_LOG=TRACE

# Set log level to INFO
export TF_LOG=INFO

# Set log level to WARN
export TF_LOG=WARN

# Set log level to ERROR
export TF_LOG=ERROR

# Disable logging
export TF_LOG=""

# Log to file
export TF_LOG_PATH=terraform.log

# Log with timestamp
export TF_LOG=DEBUG
export TF_LOG_PATH=terraform.log

9. 🌐 Set Up Environment Variables

Why?

Environment variables help manage sensitive information and configuration settings required by Terraform.

How?

AWS Example:

export AWS_ACCESS_KEY_ID="your-access-key-id"
export AWS_SECRET_ACCESS_KEY="your-secret-access-key"
export AWS_DEFAULT_REGION="us-west-2"

Add to Profile: To make these variables persistent across sessions, add them to your shell profile file (.bashrc, .zshrc, etc.):

echo 'export AWS_ACCESS_KEY_ID="your-access-key-id"' >> ~/.bashrc
echo 'export AWS_SECRET_ACCESS_KEY="your-secret-access-key"' >> ~/.bashrc
echo 'export AWS_DEFAULT_REGION="us-west-2"' >> ~/.bashrc

Terraform-Specific Variables:

# Set Terraform log level
export TF_LOG=DEBUG

# Set Terraform log path
export TF_LOG_PATH=terraform.log

# Set Terraform data directory
export TF_DATA_DIR="/custom/terraform/directory"

# Set plugin cache directory
export TF_PLUGIN_CACHE_DIR="$HOME/.terraform.d/plugin-cache"

# Disable interactive input
export TF_INPUT=0

# Set automation mode
export TF_IN_AUTOMATION=1

# Set Terraform Cloud token
export TF_API_TOKEN="your-api-token"

10. 🗂️ Organize Configuration Directory

Why?

Organizing your configuration files helps maintain clarity and structure in your Terraform projects.

How?

Create a Base Directory:

mkdir -p ~/terraform-projects/my-project
cd ~/terraform-projects/my-project

Subdirectories: Create subdirectories for different environments (e.g., dev, staging, prod):
```
mkdir dev staging prod
```

11. 🔄 Enable Command Aliases

Why?

Aliases simplify repeated command usage and can save time.

How?

Add Aliases to Profile:

echo 'alias tf="terraform"' >> ~/.bashrc
echo 'alias tfi="terraform init"' >> ~/.bashrc
echo 'alias tfp="terraform plan"' >> ~/.bashrc
echo 'alias tfa="terraform apply"' >> ~/.bashrc
echo 'alias tfaa="terraform apply -auto-approve"' >> ~/.bashrc
echo 'alias tfv="terraform validate"' >> ~/.bashrc
echo 'alias tff="terraform fmt"' >> ~/.bashrc
echo 'alias tfs="terraform state list"' >> ~/.bashrc
echo 'alias tfsh="terraform show"' >> ~/.bashrc
echo 'alias tfo="terraform output"' >> ~/.bashrc
echo 'alias tfoj="terraform output -json"' >> ~/.bashrc

Reload Profile:
```
source ~/.bashrc
```

12. 📦 Lock and Vendor Provider Versions

Why?

Locking provider versions ensures consistent and reproducible deployments.

How?

Specify Provider Versions:

# versions.tf
terraform {
  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = "~> 5.0"
    }
    azurerm = {
      source  = "hashicorp/azurerm"
      version = "~> 3.0"
    }
  }
  required_version = ">= 1.0.0"
}

Reinitialize to Install Specified Versions:
```
terraform init -upgrade
```

Lock Provider for Multiple Platforms:

terraform providers lock -platform=linux_amd64 -platform=darwin_amd64 -platform=windows_amd64

13. 📄 Generate and Use Terraform Docs

Why?

Documentation helps in understanding and maintaining Terraform configurations.

How?

Install terraform-docs:

# macOS
brew install terraform-docs

# Linux
curl -Lo ./terraform-docs https://github.com/terraform-docs/terraform-docs/releases/download/v0.16.0/terraform-docs-v0.16.0-$(uname)-amd64
chmod +x terraform-docs
sudo mv terraform-docs /usr/local/bin/

Generate Documentation:

# Generate markdown table
terraform-docs markdown table . > README.md

# Generate markdown document
terraform-docs markdown document . > README.md

# Generate JSON
terraform-docs json . > docs.json

14. 🚀 CI/CD Usage Examples

Step 1: GitHub Actions

- name: Terraform Init
  run: terraform init

- name: Terraform Validate
  run: terraform validate

- name: Terraform Plan
  run: terraform plan -out=tfplan

- name: Terraform Apply
  run: terraform apply -auto-approve tfplan

Step 2: GitLab CI/CD

validate:
  script:
    - terraform init
    - terraform validate

plan:
  script:
    - terraform init
    - terraform plan -out=tfplan
  artifacts:
    paths:
      - tfplan

apply:
  script:
    - terraform apply -auto-approve tfplan

15. 📚 Best Practices

Do's

✅ Always run terraform plan before terraform apply
✅ Use -out flag with plan and apply the saved plan
✅ Commit .terraform.lock.hcl for provider version consistency
✅ Use variable files for environment-specific configuration
✅ Enable debug logging when troubleshooting
✅ Use terraform fmt -check in CI/CD pipelines
✅ Lock provider versions in versions.tf

Don'ts

❌ Use terraform apply -auto-approve in production
❌ Commit .tfstate files to version control
❌ Ignore state lock errors
❌ Use sensitive data in plain text variables
❌ Run terraform as root unless necessary
❌ Ignore validation errors

16. 📚 Additional Resources

You are now ready to use the Terraform CLI effectively! 🚀

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🖥️ Terraform CLI: Comprehensive Usage Guide

1. 🌍 What is Terraform CLI?

2. 📦 Basic CLI Commands

Step 1: Initialize Terraform

Step 2: Format Configuration

Step 3: Validate Configuration

Step 4: Plan Changes

Step 5: Apply Changes

3. 🔄 State Management Commands

Step 1: View State

Step 2: Move Resources in State

Step 3: Remove Resources from State

Step 4: Import Resources

4. 🏗️ Workspace Commands

Step 1: List Workspaces

Step 2: Create and Switch Workspaces

5. 📊 Output Commands

Step 1: View Outputs

6. 🔧 Provider Commands

Step 1: Provider Operations

7. 🧪 Test Commands (Terraform 1.6+)

Step 1: Run Tests

8. 🐛 Debugging Commands

Step 1: Enable Debug Logging

9. 🌐 Set Up Environment Variables

Why?

How?

10. 🗂️ Organize Configuration Directory

Why?

How?

11. 🔄 Enable Command Aliases

Why?

How?

12. 📦 Lock and Vendor Provider Versions

Why?

How?

13. 📄 Generate and Use Terraform Docs

Why?

How?

14. 🚀 CI/CD Usage Examples

Step 1: GitHub Actions

Step 2: GitLab CI/CD

15. 📚 Best Practices

Do's

Don'ts

16. 📚 Additional Resources

Author by: