Terraform Training

These are simple training sessions in Terraform for both Azure and AWS.

All the base concepts are described in the Azure folder. The AWS folder contains examples of specific resources creation.

The code examples are based on Terraform 1.3.x and include some of the new syntax and functionalities. The code examples for Azure, are based on version 3.x of the provider. The code examples for AWS, are based on version 4.x of the provider. Both at the version available at the moment of creating this.

Some of the examples given are very simple and not necessarily the most secured ones. It is recommended that you follow best practices from each cloud provider when dealing with segmentation of networks, service identities, network security or other security considerations, unless I mention them myself.

By no mean, is this the only way to structure your Terraform solution. There are two main patterns that I have seen and created for myself and they all evolve around the scale of the project

As you will see, the chapters include a gradual increase of complexity both from the infrastructure side but also from the maintainers point of view. I tried to make the structures as easier to manage and follow but still you might find other structures that fit you, your team, your infrastructure, your organization structure etc.

Future Plans

Additional chapters (WIP)

Create a secure Azure design
Create a complete Azure Landing Zone Chapter
Create a secure AWS design
Create a complete AWS Landing Zone Chapter
Create a CICD pipeline chapter
Azure DevOps
GitHub Actions

Azure

TF1

Initial. Hardcoded values. Interpolation.

TF2

multiple resource at same time

TF3

Small to Medium project, start using backend for state file

TF4

Medium to Big project

TF5

Big to Very Big projects

How to (Azure)

Login to Azure

az login
Create a new Resource Group in a location given a name
```
 az group create -l northeu -n terraform-rg
```
The returned message will be a json that includes the resource group id (the long descriptor that includes the subscription id), the location and under properties will hold the provisioingState - "Succeeded" when it did.
We create a service principle for the pipelines and allow it contributor role for the resource group using the resource group id
```
 az ad sp create-for-rbac -n terraform-rg -role contributor --scopes (the id value)
```
This will create a service principle (noted as AppID) and will show us the tenantID in which it was create together with a password which is required for creating service connections in Azure DevOps.

Now we need to create a Storage Account to hold the state file

 az storage account create --resource-group terraform-rg --name tfstorage --sku Standard_LRS --encryption-services blob

The returned message will be a json with 2 keys with full permissions that were created for the storage account. We will need to use one of those to create a container in the storage account.
```
 az storage container create --name tfcontainer --account-name tfstorage -account-key (the key value)
```
Create a service connection in Azure DevOps.

General - Links

https://docs.microsoft.com/en-us/azure/developer/terraform/store-state-in-azure-storage

https://docs.microsoft.com/en-us/azure/developer/terraform/create-linux-virtual-machine-with-infrastructure

https://learn.hashicorp.com/terraform?track=azurerm

https://thorsten-hans.com/terraform-the-definitive-guide-for-azure-enthusiasts

Terraform Changes

This chapter is about the upcoming changes to both the Terraform engine and the AzureRM Provider. Additionally, an ongoing effort by Microsoft that is well worth to keep track of and that is Microsoft Verified Modules.

Links to both, towards the end of this document.

AzureRM 3.0+

In AzureRM provider version 3.0 and onward, Microsoft has split the App Service object and the Function App to be based on their kind - Windows or Linux and the App Service Plan resource name was changed to Service Plan.

Note that version 4.0 of the Provider will be released towards the end of 2022 or start of 2023.

Here is an example of an App Service Plan, before 3.0

resource "azurerm_app_service_plan" "asp" {
    name                = "${var.resource_prefix}-plan"
    location            = azurerm_resource_group.rg.location
    resource_group_name = azurerm_resource_group.rg.name
    kind                = "Windows"

    sku {
        tier = "Standard"
        size = "S1"
    }
}

Here is the same resource, after 3.0

resource "azurerm_service_plan" "asp" {
    name                = "${var.resource_prefix}-plan"
    location            = azurerm_resource_group.rg.location
    resource_group_name = azurerm_resource_group.rg.name
    kind                = "Windows"

    sku {
        tier = "Standard"
        size = "S1"
    }
}

You can see that the resource name changes from azurerm_app_service_plan to azurerm_service_plan

Here is an example for App Service, before 3.0

resource "azurerm_app_service" "webapp" {
  name                = "${var.resource_prefix}-app"
  location            = azurerm_resource_group.rg.location
  resource_group_name = azurerm_resource_group.rg.name
  app_service_plan_id = azurerm_app_service_plan.asp.id

  site_config {
      always_on = true
  }
}

Here is the same resource, after 3.0

resource "azurerm_windows_web_app" "webapp" {
  name                = "${var.resource_prefix}-app"
  location            = azurerm_resource_group.rg.location
  resource_group_name = azurerm_resource_group.rg.name
  app_service_plan_id = azurerm_app_service_plan.asp.id

  site_config {
      always_on = true
  }
}

You can see that the resource name changes from azurerm_app_service to azurerm_windows_web_app

Look at the links section and read more about the changes.

Terraform Engine 1.2

While variable validation existed since version 0.13, in the version 1.2 we now have a way to perform Pre and Post checks on our code Validation allows us to force a simple "policy" as to the content of variable values supplied and becomes highly important when working on a complex structure where modules might be created by a different team and potentially in a differernt repository all together.

In version 1.2 we can now force rules for resources, data sources and outputs. Precondition checks can check values from other data sources for example and should be used to check an assumption. Postconditions checks can check values of resources after they were applied, for example making sure a storage account was created with no public access or a VM has been assigned a Public IP before additional resources will be applied that depend on it.

Microsoft Verified Modules

While Microsoft is maintaining, together with Hashicorp, the AzureRM provider very actively, until now, modules were either created manually or introduced via the 3rd party providers and modules from the Terraform Registry https://registry.terraform.io/.

Microsoft have released quite a few modules https://registry.terraform.io/browse/modules?provider=azurerm, fully maintained and supported so all we need would be to point to their repository and use their versioning schema to pin module versions. This will also hopefully allow modules keeping synced with their AzureRM provider release cadence alleviating some of the pain points of maintaining our own modules between provider changes.

Terraform Changes - Links

AzureRM Provider 3.0 Upgrade Guide https://registry.terraform.io/providers/hashicorp/azurerm/latest/docs/guides/3.0-upgrade-guide

Terraform Engine 1.2 Custom Condition Check https://www.terraform.io/language/expressions/custom-conditions#preconditions-and-postconditions

Azure Terraform Verified Modules https://azure.github.io/Azure-Verified-Modules/

ArieHein/terraform-train