1. Deploying Infrastructure with Terraform

Question 1

Providers - Overview

• Terraform supports multiple providers.
• We have to specify the provider details for which we want to launch the infrastructure for.
• With the provider, we also have to add the tokens which will be used for authentication.
• On adding a provider, terraform init will download plugins associated with the provider.

Question 2

Providers - Update 0.13

From 0.13 onwards, Terraform requires explicit source information for any providers that are not HashiCorp-maintained, using a new syntax in the required_providers nested block inside the Terraform configuration block

Question 3

Terraform Destroy

• Terraform destroy* allows us to destroy all the resources that are created within the folder.
• Terraform destroy* with -target flag allows us to destroy the specific resource

Question 4

Terraform State File

• Terraform stores the state of the infrastructure that is being created from the TF files.
• This state allows terraform to map real-world resource to your existing configuration.
• Multiple resources in Terraform will have a separate block with the state file.
• When running a terraform plan, Terraform must know the current state of resources in order to effectively determine the changes that it needs to make to reach your desired configuration.
  
  • Current State = Current Infrastructure Resource & Configuration
  • Desired State = Infrastructure Configuration defined within the Terraform TF Files.
• Terraform will plan to match the desired state to the current state. If there is a difference between both, the desired state will take the preference.

Question 5

Providers - Versioning

• Provider plugins are released separately from Terraform itself.
• They have a different set of version numbers.
• During terraform init, if version argument is not specified, the most recent provider will be downloaded during initialization.
• For production use, you should constrain the acceptable provider versions via configuration, to ensure that new versions with breaking changes will not be automatically installed

Question 6

Providers - Types

• There are two major categories for Terraform providers:
  
  • Hashicorp Distributed
  • Third Party
• HashiCorp Distributed providers can be downloaded automatically during terraform init.
• terraform init cannot automatically download providers that are not distributed by HashiCorp.

Question 7

Providers - 3rd Party

• Third-party providers must be manually installed, since terraform init cannot automatically download them.
• Install third-party providers by placing their plugin executables in the user plugins directory.
• Plugin directory: /terraform.d/plugins

Question 8

Terraform Language

Terraform is an immutable, declarative, Infrastructure as Code provisioning language based on Hashicorp Configuration Language, or optionally JSON.