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--- devops:terraform [2021/05/26 18:36] – skipidar
+++ devops:terraform [2024/04/03 19:53] (current) – skipidar
@@ Line 1: / Line 1: @@
 ===== Terraform =====
+===Debugging===
+<sxh shell>
+# https://developer.hashicorp.com/terraform/internals/debugging
+# investigage errors
+export TF_LOG="TRACE"
+export TF_LOG_PATH="./terraform.log"
+</sxh>
+===Glossary===
+| Terraform Module |A Terraform module is a set of Terraform configuration files in a single directory.|
 Installation
@@ Line 7: / Line 23: @@
 https://www.terraform.io/intro/getting-started/build.html
+Skeleton project
+https://github.com/skipidar/terraform-skeleton
+== Apply terraform bash script ==
-Apply terraform bash script
 <sxh bash>
@@ Line 24: / Line 41: @@
 #terraform apply
+</sxh>
+== Upgrade terraform provider ==
+https://developer.hashicorp.com/terraform/tutorials/configuration-language/provider-versioning
+<sxh bash>
+terraform init -upgrade
+Initializing the backend...
+Initializing provider plugins...
+- Finding hashicorp/aws versions matching "~> 5.0"...
+- Installing hashicorp/aws v5.21.0...
+- Installed hashicorp/aws v5.21.0 (signed by HashiCorp)
+Terraform has made some changes to the provider dependency selections recorded
+in the .terraform.lock.hcl file. Review those changes and commit them to your
+version control system if they represent changes you intended to make.
+Terraform has been successfully initialized!
 </sxh>
+=== Main ===
+Create "**main.tf**"
+<sxh json>
+terraform {
+  required_providers {
+    aws = {
+      source  = "hashicorp/aws"
+      version = "~> 3.0"
+    }
+  }
+}
+provider "aws" {
+  profile = "default"
+  region  = format("%s", var.aws_region)
+}
+</sxh>
 === Variables ===
-Create "variables.tf"
+Create "**variables.tf**"
 <sxh json>
-variable "region" {
+variable "aws_region" {
-  description = "Value of the Name tag for the EC2 instance"
+  description = "The AWS region to deploy the resources into"
   type = string
-  default = "eu-west-1"
+  default = "eu-central-1"
 }
+variable "aws_account_id" {
+  description = "The AWS account identifier of the project"
+  type = string
+  default = "1234567891234"
+}
+variable "prefix" {
+  description = "The resource prefix"
+  type = string
+  default = "alf-dev-con1"
+}
+locals {
+  iot_policy = "${var.prefix}-thing2"
+}
 </sxh>
+**locals**  defines inner variables.
+Only here one can combine other variables
 Use the variable
@@ Line 53: / Line 129: @@
 }
 </sxh>
+=== Data ===
+When you define ''data'' blocks Terraform communicates with the **AWS provider** to query AWS and fetch the list of requested resources, mentioned in data-block.
+<sxh json>
+</sxh>
+You can apply filters.
+<sxh json>
+# Find the latest available AMI that is tagged with Component = web
+data "aws_ami" "web" {
+  filter {
+    name   = "state"
+    values = ["available"]
+  }
+  filter {
+    name   = "tag:Component"
+    values = ["web"]
+  }
+  most_recent = true
+}
+</sxh>
+Create **templates.tf**
+<sxh json>
+data "template_file" "tf_iot_policy" {
+  vars = {
+    aws_region = "${var.aws_region}"
+    aws_account_id = "${var.aws_account_id}"
+  }
+  template = <<EOF
+{
+  "Version": "2012-10-17",
+  "Statement": [
+    {
+      "Effect": "Allow",
+      "Action": [
+        "iot:Connect",
+        "iot:Publish",
+        "iot:Receive",
+        "iot:Subscribe"
+      ],
+      "Resource": "arn:aws:iot:$${aws_region}:$${aws_account_id}:*"
+    }
+  ]
+}
+EOF
+}
+</sxh>
+Usage
+<sxh json>
+resource "aws_iot_policy" "iot_policy" {
+  name   = "${local.iot_policy}"
+  policy = "${data.template_file.tf_iot_policy.rendered}"
+}
+</sxh>
+=== Dynamic block ===
+See https://spacelift.io/blog/terraform-dynamic-blocks
+To replace the repetitive code as here in a module:
+<sxh json>
+resource "azurerm_virtual_network" "dynamic_block" {
+  name                = "vnet-dynamicblock-example-centralus"
+  resource_group_name = azurerm_resource_group.dynamic_block.name
+  location            = azurerm_resource_group.dynamic_block.location
+  address_space       = ["10.10.0.0/16"]
+  subnet {
+    name           = "snet1"
+    address_prefix = "10.10.1.0/24"
+  }
+  subnet {
+    name           = "snet2"
+    address_prefix = "10.10.2.0/24"
+  }
+  subnet {
+    name           = "snet3"
+    address_prefix = "10.10.3.0/24"
+  }
+  subnet {
+    name           = "snet4"
+    address_prefix = "10.10.4.0/24"
+  }
+}
+</sxh>
+Use the "dynamic" block
+<sxh json>
+resource "azurerm_virtual_network" "dynamic_block" {
+  name                = "vnet-dynamicblock-example-centralus"
+  resource_group_name = azurerm_resource_group.dynamic_block.name
+  location            = azurerm_resource_group.dynamic_block.location
+  address_space       = ["10.10.0.0/16"]
+  dynamic "subnet" {
+    for_each = var.subnets
+    iterator = item   #optional
+    content {
+      name           = item.value.name
+      address_prefix = item.value.address_prefix
+    }
+  }
+}
+</sxh>
+Declare a variable in your module
+<sxh json>
+variable "subnets" {
+  description = "list of values to assign to subnets"
+  type = list(object({
+    name           = string
+    address_prefix = string
+  }))
+}
+</sxh>
+**USAGE of your module**
+Assigning values to the variable "subnets", which are taken by the module above.
+<sxh json>
+subnets = [
+  { name = "snet1", address_prefix = "10.10.1.0/24" },
+  { name = "snet2", address_prefix = "10.10.2.0/24" },
+  { name = "snet3", address_prefix = "10.10.3.0/24" },
+  { name = "snet4", address_prefix = "10.10.4.0/24" }
+]
+</sxh>