AWS & Terraform Bootcamp

Terraform commans

If you run terraform without any arguments you get a list of all available commands. The output should look like this:

						PS C:\terraform> .\terraform.exe init
						Usage: terraform [global options] $lt subcommand $gt [args]

							The available commands for execution are listed below.
							The primary workflow commands are given first, followed by
							less common or more advanced commands.
							
							Main commands:
							  init          Prepare your working directory for other commands
							  validate      Check whether the configuration is valid
							  plan          Show changes required by the current configuration
							  apply         Create or update infrastructure
							  destroy       Destroy previously-created infrastructure
							
							All other commands:
							  console       Try Terraform expressions at an interactive command prompt
							  fmt           Reformat your configuration in the standard style
							  force-unlock  Release a stuck lock on the current workspace
							  get           Install or upgrade remote Terraform modules
							  graph         Generate a Graphviz graph of the steps in an operation
							  import        Associate existing infrastructure with a Terraform resource
							  login         Obtain and save credentials for a remote host
							  logout        Remove locally-stored credentials for a remote host
							  metadata      Metadata related commands
							  modules       Show all declared modules in a working directory
							  output        Show output values from your root module
							  providers     Show the providers required for this configuration
							  refresh       Update the state to match remote systems
							  show          Show the current state or a saved plan
							  state         Advanced state management
							  taint         Mark a resource instance as not fully functional
							  test          Execute integration tests for Terraform modules
							  untaint       Remove the 'tainted' state from a resource instance
							  version       Show the current Terraform version
							  workspace     Workspace management
							
							Global options (use these before the subcommand, if any):
							  -chdir=DIR    Switch to a different working directory before executing the
											given subcommand.
							  -help         Show this help output, or the help for a specified subcommand.
							  -version      An alias for the "version" subcommand.
					

Terraform Main Commands

In this section we learn about the subcommands that terraform uses to do its job, mainly there are

1. plan: compare IaC code, with system state and actual resources built in the cloud
2. apply: make any changes needed to align our code with the Cloud resources
3. destroy: Let's safe money and remove everything until we need it again.

Terraform additional usefule Commands

In this section we learn about the subcommands that terraform uses to do its job, mainly there are

1. fmt: compare IaC code, with system state and actual resources built in the cloud
2. apply: make any changes needed to align our code with the Cloud resources
3. destroy: Let's safe money and remove everything until we need it again.

Remaining Commands

The remaining commands are advanced and I will cover them in a future video of this series.

Building resources quickly

To find the neccessary syntax for a given rerources we can go to the AWS provider docs on the Hashicorp Website.

Add SNS test resource

To test that terraform works correctly we create a test resource, it should adhere to these requirements:

1. just a few lines of code
2. deploys quickly
3. no dependecies on other resources

SNS topics are perfect for this, they only need 3 lines of code, deploy within a few seconds and can exist by and on itself. VPCs (virtual networks) need more code, and S3 buckets have to be globally unique making them less suitable for testing.

so lets create a file named main.tf an put in the following code. The code and more info can be found here

						resource "aws_sns_topic" "test_topics" {
							name = "first-test-resource"
						  }
					

terraform planning

Running terraform plan we get some output like the one below showing us which resources terraform would created (marked with a green + ), destroy (marked with a red - ) or changed (marked with a yello ~)

						PS C:\terraform> .\terraform.exe plan
						Terraform used the selected providers to generate the following execution plan. Resource actions are indicated with the following symbols:
						+ create
					  
					  	Terraform will perform the following actions:
					  
						# aws_sns_topic.test_topics will be created
						+ resource "aws_sns_topic" "test_topics" {
							+ arn                         = (known after apply)
							+ beginning_archive_time      = (known after apply)
							+ content_based_deduplication = false
							+ fifo_topic                  = false
							+ id                          = (known after apply)
							+ name                        = "first-test-resource"
							+ name_prefix                 = (known after apply)
							+ owner                       = (known after apply)
							+ policy                      = (known after apply)
							+ signature_version           = (known after apply)
							+ tags_all                    = (known after apply)
							+ tracing_config              = (known after apply)
						  }
					  
					  Plan: 1 to add, 0 to change, 0 to destroy.
					

terraform applying

Running terraform plan we get some output like the one below showing us which resources terraform would created (marked with a green + ), destroy (marked with a red - ) or changed (marked with a yello ~)

						PS C:\terraform> .\terraform.exe plan
						Terraform used the selected providers to generate the following execution plan. Resource actions are indicated with the following symbols:
						+ create
					  
					  Terraform will perform the following actions:
					  
						# aws_sns_topic.test_topics will be created
						+ resource "aws_sns_topic" "test_topics" {
							+ arn                         = (known after apply)
							+ beginning_archive_time      = (known after apply)
							+ content_based_deduplication = false
							+ fifo_topic                  = false
							+ id                          = (known after apply)
							+ name                        = "first-test-resource"
							+ name_prefix                 = (known after apply)
							+ owner                       = (known after apply)
							+ policy                      = (known after apply)
							+ signature_version           = (known after apply)
							+ tags_all                    = (known after apply)
							+ tracing_config              = (known after apply)
						  }
					  
					  Plan: 1 to add, 0 to change, 0 to destroy.
					  
					  Do you want to perform these actions?
						Terraform will perform the actions described above.
						Only 'yes' will be accepted to approve.
					  
						Enter a value: yes
					  
					  aws_sns_topic.test_topics: Creating...
					  aws_sns_topic.test_topics: Creation complete after 1s [id=arn:aws:sns:us-east-2:929529788344:first-test-resource]
					  Apply complete! Resources: 1 added, 0 changed, 0 destroyed.
					

terraform applying

Running terraform plan we get some output like the one below showing us which resources terraform would created (marked with a green + ), destroy (marked with a red - ) or changed (marked with a yello ~)

						PS C:\terraform> .\terraform.exe plan
						Terraform used the selected providers to generate the following execution plan. Resource actions are indicated with the following symbols:
						+ create
					  
					  Terraform will perform the following actions:
					  
						# aws_sns_topic.test_topics will be created
						+ resource "aws_sns_topic" "test_topics" {
							+ arn                         = (known after apply)
							+ beginning_archive_time      = (known after apply)
							+ content_based_deduplication = false
							+ fifo_topic                  = false
							+ id                          = (known after apply)
							+ name                        = "first-test-resource"
							+ name_prefix                 = (known after apply)
							+ owner                       = (known after apply)
							+ policy                      = (known after apply)
							+ signature_version           = (known after apply)
							+ tags_all                    = (known after apply)
							+ tracing_config              = (known after apply)
						  }
					  
					  Plan: 1 to add, 0 to change, 0 to destroy.
					  
					  Do you want to perform these actions?
						Terraform will perform the actions described above.
						Only 'yes' will be accepted to approve.
					  
						Enter a value: yes
					  
					  aws_sns_topic.test_topics: Creating...
					  aws_sns_topic.test_topics: Creation complete after 1s [id=arn:aws:sns:us-east-2:929529788344:first-test-resource]
					  Apply complete! Resources: 1 added, 0 changed, 0 destroyed.
					

terraform applying

After removing the sns topic from the main.tf file and running terraform plan we see in the output below how terraform would remove the sns topic if we ran terraform apply.

						PS C:\terraform> .\terraform.exe plan
						aws_sns_topic.test_topics: Refreshing state... [id=arn:aws:sns:us-east-2:929529788344:first-test-resource]
						hoolahoop
whyisitnotworking
						Terraform used the selected providers to generate the following execution plan. Resource actions are indicated with the following symbols:
						  - destroy
						
						Terraform will perform the following actions:
						
						  # aws_sns_topic.test_topics will be destroyed
						  # (because aws_sns_topic.test_topics is not in configuration)
						  - resource "aws_sns_topic" "test_topics" {
							  - application_success_feedback_sample_rate = 0 -> null
							  - arn                                      = "arn:aws:sns:us-east-2:929529788344:first-test-resource" -> null
							  - content_based_deduplication              = false -> null
							  - fifo_topic                               = false -> null
							  - firehose_success_feedback_sample_rate    = 0 -> null
							  - http_success_feedback_sample_rate        = 0 -> null
							  - id                                       = "arn:aws:sns:us-east-2:929529788344:first-test-resource" -> null
							  - lambda_success_feedback_sample_rate      = 0 -> null
							  - name                                     = "first-test-resource" -> null
							  - owner                                    = "929529788344" -> null
							  - policy                                   = jsonencode(
									{
									  - Id        = "__default_policy_ID"
									  - Statement = [
										  - {
											  - Action    = [
												  - "SNS:GetTopicAttributes",
												  - "SNS:SetTopicAttributes",
												  - "SNS:AddPermission",
												  - "SNS:RemovePermission",
												  - "SNS:DeleteTopic",
												  - "SNS:Subscribe",
												  - "SNS:ListSubscriptionsByTopic",
												  - "SNS:Publish",
												]
											  - Condition = {
												  - StringEquals = {
													  - "AWS:SourceOwner" = "929529788344"
													}
												}
											  - Effect    = "Allow"
											  - Principal = {
												  - AWS = "*"
												}
											  - Resource  = "arn:aws:sns:us-east-2:929529788344:first-test-resource"
											  - Sid       = "__default_statement_ID"
											},
										]
									  - Version   = "2008-10-17"
									}
								) -> null
							  - signature_version                        = 0 -> null
							  - sqs_success_feedback_sample_rate         = 0 -> null
							  - tags_all                                 = {} -> null
								# (17 unchanged attributes hidden)
							}
						
						Plan: 0 to add, 0 to change, 1 to destroy.
						
						───────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────
						
						Note: You didn't use the -out option to save this plan, so Terraform can't guarantee to take exactly these actions if you run "terraform apply" now.