DevOps Classroom Series – 28/May/2020

Types in Terraform Configuration Language

• Simple/Primitive Types:

  • string
  • number
  • bool

• Complex Types

  • Collection Types:
    • list: list of any type. list(bool) is list of booleans, list => list(any)
    • map
    • set
  • Structural Types:
    • object
    • tuple

• Dynamic Type: any

• Examples

  • You can define your own object type for aws credentials sytnax is object( { access_key=string, secret_key=string, region=string } ) and the input would be

  {
      access_key 	= "jkashfkjdahfkajs"
      secret_key	= "klsjdflkdsjdlafs"
      region     	= "us-west-2"
  }
  

• Exampes with variables: All the variables can eb defined using any of the above types

variable "bucketname" {
    type    = string
    default = "yourbucketname.com" 
}

variable "regions" {
    type    = list(string),
    default = ["us-west-1", "us-west-2", "us-east-1", "us-east-2" ]
}

variable "aws_credentials" {
    type    = object( { access_key=string, secret_key=string, region=string } )
    default = {
        access_key 	= "jkashfkjdahfkajs"
        secret_key	= "klsjdflkdsjdlafs"
        region     	= "us-west-2"
    }
}

• Now show the output as public ip address to the user & for this we would navigate to Attribute section of the resource
• The terraform template looks like

provider "aws" {
  
}

variable "securitygroupid" {
    type    = string
}

variable "keyname" { 
    type    = string
}


resource "aws_instance" "firstec2" {
    ami                             = "ami-003634241a8fcdec0"
    instance_type                   = "t2.micro"
    key_name                        = var.keyname
    vpc_security_group_ids          = [ var.securitygroupid ]
    associate_public_ip_address     = true
    tags                            = {
        Name                        = "firstec2"
    }
}

output "public-ip" {
  value = aws_instance.firstec2.public_ip
}

output "private-ip" {
  value = aws_instance.firstec2.private_ip
}

• For the output Refer Here

Terraform resource dependencies

• Lets create ec2 machine, vpc and one s3 bucket, The order or creation should be
  • vpc
  • s3 bucket
  • ec2 machine
• use depends_on in resources

provider "aws" {
  
}

variable "securitygroupid" {
    type    = string
}

variable "keyname" { 
    type    = string
}

resource "aws_instance" "firstec2" {
    ami                             = "ami-003634241a8fcdec0"
    instance_type                   = "t2.micro"
    key_name                        = var.keyname
    vpc_security_group_ids          = [ var.securitygroupid ]
    associate_public_ip_address     = true
    tags                            = {
        Name                        = "firstec2"
    }

    depends_on                      = [ aws_s3_bucket.myfirsts3bucket]
}

resource "aws_vpc" "myfirstvpc" {
    cidr_block                      = "192.168.0.0/16"
  
}

resource "aws_s3_bucket" "myfirsts3bucket" {
    bucket                          = "skjdfhkjsah.com"

    depends_on                      = [ aws_vpc.myfirstvpc ]
  
}

Create Multiple resources and give a different name

• Add three subnets to the vpc and names of the subnets should be taken from variable
• Use count to create multiple resources and count.index to know current iteration

variable "securitygroupid" {
    type    = string
}

variable "keyname" { 
    type    = string
}

variable "subnetnames" {
    type    = list(string)
    default = [ "subnet1", "subnet2", "subnet3"]
}

variable "cidrrnages" {
    type    = list(string)
    default = ["192.168.0.0/24", "192.168.1.0/24", "192.168.2.0/24"]
}

resource "aws_instance" "firstec2" {
    ami                             = "ami-003634241a8fcdec0"
    instance_type                   = "t2.micro"
    key_name                        = var.keyname
    vpc_security_group_ids          = [ var.securitygroupid ]
    associate_public_ip_address     = true
    tags                            = {
        Name                        = "firstec2"
    }

    depends_on                      = [ aws_s3_bucket.myfirsts3bucket]
}

resource "aws_vpc" "myfirstvpc" {
    cidr_block                      = "192.168.0.0/16"
  
}

resource "aws_s3_bucket" "myfirsts3bucket" {
    bucket                          = "skjdfhkjsah.com"

    depends_on                      = [ aws_vpc.myfirstvpc ]
  
}

resource "aws_subnet" "subnet" {
    count                           = 3

    vpc_id                          = aws_vpc.myfirstvpc.id
    cidr_block                      = var.cidrrnages[count.index]
    tags                            = {
        Name                        = var.subnetnames[count.index]
    }

    depends_on                      = [ aws_vpc.myfirstvpc ]
  
}