terraform.md

Links

• registry
• documentation
• configuration language
• cli commands
• providers
• cloud providers
• terraform core
• terraform providers
• terraform examples

Workflow

• workflow
  • manage different versions of terraform at one place
• valid
  • check errors
• state
  • create from aws
• src
  • create dependency graph
• plan
  • pretty print for output plan

# download plugins into folder .terraform
terraform init 

# set logging level: TRACE, INFO, WARN, ERROR
export TF_LOG="DEBUG"

# dry run
terraform plan
terraform plan -out will-by-applied.zip

# apply configuration
terraform apply
terraform apply -auto-approve
terraform apply will-by-applied.zip

# apply state from another file 
# skip warning: cannot import state with lineage
terraform state push -force terraform.tfstate

# remove all resources
terraform destroy


# visualisation for resources
# sudo apt install graphviz
terraform graph | dot -Tpng > out.png

# list of providers
terraform providers

# validation of current source code
terraform validate

# show resources
# get all variables for using in resources
terraform show

terraform console
# docker_image.apache.id

cli

list of the commands

cli configuration file

cat ~/.terraformrc

plugin_cache_dir   = "$HOME/.terraform.d/plugin-cache"
disable_checkpoint = true

HCL configuration language

variables

input variables

usage inside the code

some_resource "resource-name" {
  resource_parameter = var.p1
}

possible way for input variables:

• terraform.tfvars, terraform.tfvars.json

  variable "p1" {
     default = "my own default value"
  }

• cli
  • cli var

  terraform apply -var 'p1=this is my parameter'
  terraform apply -var='p1=this is my parameter'  
  terraform apply -var='p1=["this","is","my","parameter"]'  
  terraform apply -var='p1={"one":"this","two":"is"}'    

  • cli var file

  terraform apply -var-file="staging.tfvars"

  p1 = "this is my param"
  p2 = [
    "one", 
    "two", 
  ]
  p3 = {
    "one": "first",
    "two": "second"
  }

• environment variables

export TF_VAR_p1="this is my parameter"
export TF_VAR_p1=["this","is","my","parameter"]  

output variables

terraform code

output "my_output_param" {
   value = some_resource.value.sub_param_1
}

terraform execution example

terraform output my_input_param

workspace

example of usage in configuration

resource "aws_instance" "one_of_resources" {
  tags = {
    Name = "web - ${terraform.workspace}"
  }
}

terraform workspace list
terraform workspace new attempt_1
terraform workspace show
terraform workspace select default
terraform workspace select attempt_1

some inner mechanism

# workspace with name "default"
.terraform.tfstate
.terraform.tfstate.backup
./terraform.tfstate.d

# workspace with name "attempt_1"
./terraform.tfstate.d/attempt_1
./terraform.tfstate.d/attempt_1/terraform.tfstate.backup
./terraform.tfstate.d/attempt_1/terraform.tfstate

# workspace with name "attempt_2" - has not applied yet
./terraform.tfstate.d/attempt_2

backend

Holding information about

• current state
• configuration

configuration example

terraform {  
    backend "s3" {
        bucket  = "aws-terraform-remote-store"
        encrypt = true
        key     = "terraform.tfstate"    
        region  = "eu-west-1"  
    }
}