Gain insights into Infrastructure as Code with Terraform, sharpen your skills, and prepare for the HashiCorp Terraform Associate certification in a cloud-agnostic way.

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This course is designed to help learners obtain the Terraform Associate certification from HashiCorp. 

You’ve likely picked up this course because you dabbled in Terraform as a hobbyist or in a
development environment, and you’re excited about the possibilities of deploying Infrastructure 
as Code (IaC). It will enable you to sharpen your skills and prove your knowledge with a certification from HashiCorp. Terraform is an amazing tool to deploy Infrastructure as Code in a cloud-agnostic way. We’re excited to share our accumulated knowledge with you through this course.

HashiCorp Terraform Certified Associate Preparation Guide

The creation and manipulation of resources managed by Terraform need to be tracked in some
manner. Terraform achieves this through the implementation of **state**. When a resource is created, such as an EC2 instance in AWS, Terraform creates an entry in the state that maps the metadata about
the resource (such as `instance-id`) to key/value pairs in the entry. The tracking of resource metadata
serves multiple functions.


# Idempotence

Each time a Terraform configuration is planned or applied, Terraform checks for any changes required to the environment to match the desired configuration. Only those resources that require changes will be updated, and all other resources will be left alone. Terraform won’t make any changes to the environment if there aren’t any made to the configuration. The state is what allows Terraform to map the resources defined in the configuration to the resources that exist in the real world.


# Deducing dependencies easily

Imagine a scenario where we’ve removed a subnet and EC2 instance from a configuration. Terraform will attempt to destroy those resources the next time we apply the configuration. The EC2 instance must be removed before the subnet because the instance is dependent on the subnet.

The EC2 instance referenced the subnet when the resources were created, so Terraform found the dependency when building its graph. With both resources removed from the configuration, Terraform can’t deduce the dependency by building a graph.

Terraform solves this problem with state. Terraform maintains a list of dependencies in the state file so that it can properly deal with dependencies that no longer exist in the current configuration.


# Performance

 The state is a representation of the current state of the world as Terraform understands it. When planning a change, Terraform needs to look at the resources and their attributes to determine if changes are necessary. Do the EC2 instances need a new metadata tag? Terraform can check the `tags` attribute in the state for the EC2 instance and make a quick decision. While Terraform could query resources directly for each planning run, planning performance would rapidly degrade as the infrastructure grows in scale.

By default, Terraform will refresh the state before planning each run, but Terraform can be told to skip the refresh with the `--refresh=false` argument to improve performance. The `-target` argument can be used to direct a particular resource to refresh without triggering a full refresh of the state. The state can be periodically refreshed when needed in order to keep up with changes without requiring a full scan during each plan.

It’s important to note that choosing not to refresh the state means that the reality of our infrastructure deployment may not match what’s in the state file. This can lead to inconsistent results or outright failure when we apply the plan. The risk of not refreshing the state should be balanced against any performance improvements.


# Collaboration

 The state keeps track of an applied configuration’s version and supports the locking of the state during updates. With the storage of state in a remote shared location, teams are able to collaborate on deployments without overwriting each other’s work.


# Key takeaways
Terraform state enables the mapping of real-world instances to resources in a configuration. It improves the performance of the planning engine and collaboration among teams.



Learn about Terraform state and its benefits.

Introduction to the Course

Introduction to Infrastructure as Code

Basics of Terraform

Outside the Workflow: Using the Terraform CLI

Terraform Modules

Navigate Terraform Workflow

Implement and Maintain State

Read, Generate, and Modify Configuration

Understand Terraform Enterprise Capabilities

Conclusion

Benefits of State

Idempotence