Terraform for the Absolute Beginners - udemy - labs

course notes

• https://kodekloud.com/lessons/labs-4/

lab 01: HCL Basics

link

Terraform extension: .tf

main.tf:

resourc "local_file" "games" {
  file = "/root/favorit-games"
  content = "FIFA 21"
}

• resource type: local_file
• resource name: games
• provider: local
• 3 phases of terraform:
  1. init
  2. plan
  3. apply
• in the main.tf there are two errors:
  1. a missing required argument: filename
  2. an invalid argument: file
  • this info can be checked in the docs here

If you don't want to have the contents of the file being created to be echoed on the screen, use the resource type local_sensitive_file.

lab 02: Terraform Providers

main.tf:

resource "local_file" "things-to-do" {
  filename = "/root/things-to-do.txt"
  content = "Clean my room before Christmas\nComplete the CKA Certification!"
}

resource "local_file" "more-things-to-do" {
  filename = "/root/more-things-to-do.txt"
  content = "Learn how to play Astronomia on the guitar!"
}

In both resources, the provider is local.

Provider types:

• official
  • hashicorp/<provider>
• partner
  • registry.terraform.io/<organization>/<provider>
• community
  • registry.terraform.io/<username>/<provider>

In the lab there was an example with registry.terraform.io/<somename>/ansible. What makes it clear that it refers to a community plugin is the fact that ansible is managed by redhat. So, previous knowledge is required.

lab 03: Multiple Providers

Nothing very significant...

When we change the .tf file we need to run terraform init again.

lab 04: Variables

variable types:

• string
• number
• bool
• any
• list
• map
• set (like a list, but with no repetition)
• object
• tuple (like a list, but with mixed types)

Variables are accessed by prefixing the var name with var.

lab 05: Using variables in terraform

getting vars from env: ENV_VAR_<variable_name>

The argument for -var-file is a a *.tfvars file.

variáveis em arquivos .tfvars são definidas simplesmente assim:

var_name = var_value

para que as variáveis sejam carregadas, é necessário que isso seja explicitado no arquivo variables.tf.

lab 06: Resource attributes

Some resources don't need any arguments. Example:

resource "time_static" "time_update" {
}

To access the id we use time_static.time_update.id.

Interpolation: `"Time stamp of this file is ${time_static.time_update.id}"

lab 07: Resource Dependencies

Declaring an explicit dependency:

resource "local_file" "pet" {
  filename = var.filename
  content = "My favorite pet is Mr.Cat"
  # here #############
  depends_on = [
    random_pet.my-pet
  ]
  ####################
}

resource "random_pet" "my-pet" {
  prefix = var.prefix
  separator = var.separator
  length = var.length
}

lab 08: Output Variables

output "<variable-name>" {
  value = "<variable-value>"
  <arguments>
}

inspect the value with terraform output or terraform output <variable-name>.

lab 09: Terraform State

• Terraform State file is placed in the same dir as the .tf files.
• Default name: terraform.tfstate
• The extension: .tfstate
• Format is JSON.

The command terraform show is useful to check the terraform state.

NOTE: Terraform State stores sensitive data.

lab 10: Terraform Commands

Use terraform validate to check your .tf config files.

Use terraform fmt to format your code.

Use terraform providers to list the providers currently in use.

lab 11: Data Sources

Data Sources go in a data block.

resource vs. data source:

lab 12: count and for_each

count

# main.tf
resource "local_file" "pet" {
  count = 3
  filename = var.filename[count.index]
}

# variables.tf
variable "filename" {
  default = [
    "/root/pets.txt",
    "/root/dogs.txt",
    "/root/cats.txt"
  ]
}

Note that count = 3 is hardcoded above 👆

A more dynamic way would be to use count = length(var.filename)

for_each

# main.tf
resource "local_file" "pet" {
  filename = each.value
  for_each = toset(var.filename)
}

# variables.tf
variable "filename" {
  type = list(string)
  default = [
    "/root/pets.txt",
    "/root/dogs.txt",
    "/root/cats.txt"
  ]
}

• count vs. for_each
  • count creates resources as a list
  • for_each creates resources as a map