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Terraform
General Information
“Terraform enables you to safely and predictably create, change, and improve infrastructure. It is an open source tool that codifies APIs into declarative configuration files that can be shared amongst team members, treated as code, edited, reviewed, and versioned.”
Site
- Official Site: https://www.terraform.io/
- Downloads: https://www.terraform.io/downloads.html
- Getting started: https://www.terraform.io/intro/getting-started/install.html
Checklist
- AWS Account
Install Terraform
Installing Terraform on Linux.
- Visit downloads page: https://www.terraform.io/downloads.html
- Copy download link
- On Linux server, wget the link to download (example link)
wget https://releases.hashicorp.com/terraform/0.11.7/terraform_0.11.7_linux_amd64.zip
- Unzip single binary, move into /usr/local/bin
unzip terraform_0.11.7_linux_amd64.zip mv terraform /usr/local/bin/
- Verify
terraform --version
Configure AWS Credentials for Use
- Login to your AWS account, create access keys for CLI use and download the file.
- Create an AWS credentials file in your home directory
vim ~/.aws/credentials # AWS Credentials [default] aws_access_key_id = "access-key-id-here" aws_secret_access_key = "secret-key-here"
- The profile name is “default” and can now be referenced in the terraform config files.
- Lock down permissions
chmod 600 ~/.aws/credentials
Terraform Example: 2 Tier VPC
Pre-Req: AWS account and access keys setup/configured in the previous section.
Creating a 2-tier VPC (public and private subnets), utilizing 3 availability zones in US-West (Oregon).
This will create the all of the virtual infrastructure to start creating services inside of.
File Structure
Files can be named anything, as long as it ends in a “.tf”. Terraform will load all files in a directory structure below it that end in that.
Example Structure
├── main.tf # Terraform root config (does not have to be 'main.tf') ├── outputs.tf # Output data that can be displayed ├── site # A local defined module called "site" │ ├── nat_gateway.tf │ ├── outputs.tf │ ├── routes.tf │ ├── security_groups.tf │ ├── subnets.tf │ ├── variables.tf │ └── vpc.tf ├── terraform.tfstate # Terrform creates this file to keep track of resource state ├── terraform.tfstate.backup # And this is just a backup of state └── variables.tf # Variables defined here that can be used or passed into modules
File Contents
Contents of the above config files.
File Contents: Root Files
Files in the top level directory. Ordered in a way that is easier to follow.
- main.tf
# Title: main.tf # Description: Main terraform config file. Define provider and load other modules # AWS Credentials auto loaded from ~/.aws/credentials ## AWS Provider and Region provider "aws" { region = "${var.region}" profile = "default" } ## Module: Site Infrastructure Setup module "site" { source = "./site" availability_zones = "${var.availability_zones}" public_subnet01_cidr = "${var.public_subnet01_cidr}" public_subnet02_cidr = "${var.public_subnet02_cidr}" public_subnet03_cidr = "${var.public_subnet03_cidr}" private_subnet01_cidr = "${var.private_subnet01_cidr}" private_subnet02_cidr = "${var.private_subnet02_cidr}" private_subnet03_cidr = "${var.private_subnet03_cidr}" vpc_cidr = "${var.vpc_cidr}" }
- variables.tf
# Title: variables.tf # Description: Root defined variables ####-- Global Variables --#### # AWS Region To Use variable "region" { default = "us-west-2" } # Availability Zones To Use variable "availability_zones" { type = "list" default = [ "us-west-2a" , "us-west-2b" , "us-west-2c" ] } ####-- VPC Variables --#### # VPC Network variable "vpc_cidr" { description = "CIDR for the whole VPC" # /21 = 2046 IPs, 10.0.0.1 - 10.0.7.254 default = "10.0.0.0/21" } # Public Subnet 01 (with IGW) variable "public_subnet01_cidr" { description = "CIDR for the Public Subnet" # /25 = 126 IPs, 10.0.0.1 - 10.0.0.126 default = "10.0.0.0/25" } # Public Subnet 02 (with IGW) variable "public_subnet02_cidr" { description = "CIDR for the Public Subnet" # /25 = 126 IPs, 10.0.0.129 - 10.0.0.254 default = "10.0.0.128/25" } # Public Subnet 03 (with IGW) variable "public_subnet03_cidr" { description = "CIDR for the Public Subnet" # /25 = 126 IPs, 10.0.1.1 - 10.0.1.126 default = "10.0.1.0/25" } # Private Subnet 01 (no IGW) variable "private_subnet01_cidr" { description = "CIDR for the Private Subnet" # /23 = 510 IPs, 10.0.2.1 - 10.0.3.254 default = "10.0.2.0/23" } # Private Subnet 02 (no IGW) variable "private_subnet02_cidr" { description = "CIDR for the Private Subnet" # /23 = 510 IPs, 10.0.4.1 - 10.0.5.254 default = "10.0.4.0/23" } # Private Subnet 03 (no IGW) variable "private_subnet03_cidr" { description = "CIDR for the Private Subnet" # /23 = 510 IPs, 10.0.6.1 - 10.0.7.254 default = "10.0.6.0/23" }
- outputs.tf
# Title: outputs.tf # Description: Outputs from resources saved as variables # Pull the VPC ID from the site module output "vpc_id" { value = "${module.site.vpc_id}" }
File Contents: Site Module Files
Files in the site/ module directory. Ordered in a way that is easier to follow.
- variables.tf
# Title: site/variables.tf # Description: Required input variables from the parent file (../main.tf) # Availability Zones: Pass in from main variables variable "availability_zones" { type = "list" } # VPC CIDR: Pass in from main variables variable "vpc_cidr" {} # Public Subnets (with IGW): Pass in from main variable "public_subnet01_cidr" {} variable "public_subnet02_cidr" {} variable "public_subnet03_cidr" {} # Private Subnets (no IGW): Pass in from main variable "private_subnet01_cidr" {} variable "private_subnet02_cidr" {} variable "private_subnet03_cidr" {}
- vpc.tf
# Title: vpc.tf # Description: Create a VPC and attach an internet gateway ####-- VPC --#### # VPC: Creation resource "aws_vpc" "myvpc" { cidr_block = "${var.vpc_cidr}" enable_dns_hostnames = true tags { Name = "myvpc" } } # VPC: Internet Gateway resource "aws_internet_gateway" "myigw" { vpc_id = "${aws_vpc.myvpc.id}" tags { Name = "myigw" } }
- subnets.tf
# Title: subnets.tf # Description: Create subnets ####-- Subnets --#### # Public Subnet 01 resource "aws_subnet" "subnet01-public" { vpc_id = "${aws_vpc.myvpc.id}" cidr_block = "${var.public_subnet01_cidr}" availability_zone = "${element(var.availability_zones, 0)}" tags { Name = "subnet_public01" } } # Public Subnet 02 resource "aws_subnet" "subnet02-public" { vpc_id = "${aws_vpc.myvpc.id}" cidr_block = "${var.public_subnet02_cidr}" availability_zone = "${element(var.availability_zones, 1)}" tags { Name = "subnet_public02" } } # Public Subnet 03 resource "aws_subnet" "subnet03-public" { vpc_id = "${aws_vpc.myvpc.id}" cidr_block = "${var.public_subnet03_cidr}" availability_zone = "${element(var.availability_zones, 2)}" tags { Name = "subnet_public03" } } # Private Subnet 01 resource "aws_subnet" "subnet01-private" { vpc_id = "${aws_vpc.myvpc.id}" cidr_block = "${var.private_subnet01_cidr}" availability_zone = "${element(var.availability_zones, 0)}" tags { Name = "subnet_private01" } } # Private Subnet 02 resource "aws_subnet" "subnet02-private" { vpc_id = "${aws_vpc.myvpc.id}" cidr_block = "${var.private_subnet02_cidr}" availability_zone = "${element(var.availability_zones, 1)}" tags { Name = "subnet_private02" } } # Private Subnet 03 resource "aws_subnet" "subnet03-private" { vpc_id = "${aws_vpc.myvpc.id}" cidr_block = "${var.private_subnet03_cidr}" availability_zone = "${element(var.availability_zones, 2)}" tags { Name = "subnet_private03" } }
- nat_gateway.tf
# Title: nat_gateway.tf # Description: Create a NAT gateway for private subnets # Note: For true high availabity, you will want: # -An EIP and NAT GW per public subnet # -Route table per private subnet to route to NAT GW in same AZ # Create the required Elastic IPs to be assigned to the NAT Gateways resource "aws_eip" "eip_nat01" { vpc = true } resource "aws_eip" "eip_nat02" { vpc = true } resource "aws_eip" "eip_nat03" { vpc = true } # Create the NAT Gateways resource "aws_nat_gateway" "nat_gw01" { subnet_id = "${aws_subnet.subnet01-public.id}" allocation_id = "${aws_eip.eip_nat01.id}" tags { Name = "nat_gw01" } # Dependencies: Internet Gateway and EIP depends_on = ["aws_internet_gateway.myigw", "aws_eip.eip_nat01"] } resource "aws_nat_gateway" "nat_gw02" { subnet_id = "${aws_subnet.subnet02-public.id}" allocation_id = "${aws_eip.eip_nat02.id}" tags { Name = "nat_gw02" } # Dependencies: Internet Gateway and EIP depends_on = ["aws_internet_gateway.myigw", "aws_eip.eip_nat02"] } resource "aws_nat_gateway" "nat_gw03" { subnet_id = "${aws_subnet.subnet03-public.id}" allocation_id = "${aws_eip.eip_nat03.id}" tags { Name = "nat_gw03" } # Dependencies: Internet Gateway and EIP depends_on = ["aws_internet_gateway.myigw", "aws_eip.eip_nat03"] } # Route to the NAT Gateway provided elsewhere (in private route table)
- routes.tf
#Title: routes.tf # Description: Route tables for subnets ####-- Routes --#### ##-- Public Subnet Routes --## # Public Route Table - Default Route to Internet Gateway resource "aws_route_table" "rt_public" { vpc_id = "${aws_vpc.myvpc.id}" route { cidr_block = "0.0.0.0/0" gateway_id = "${aws_internet_gateway.myigw.id}" } tags { Name = "rt_public" } } # Associate Subnet Public 01 with Route Table resource "aws_route_table_association" "rt_assoc_public01" { subnet_id = "${aws_subnet.subnet01-public.id}" route_table_id = "${aws_route_table.rt_public.id}" } # Associate Subnet Public 02 with Route Table resource "aws_route_table_association" "rt_assoc_public02" { subnet_id = "${aws_subnet.subnet02-public.id}" route_table_id = "${aws_route_table.rt_public.id}" } # Associate Subnet Public 03 with Route Table resource "aws_route_table_association" "rt_assoc_public03" { subnet_id = "${aws_subnet.subnet03-public.id}" route_table_id = "${aws_route_table.rt_public.id}" } ##-- Private Subnet Routes --## # Private Route Tables - Default Route to NAT GW in each AZ resource "aws_route_table" "rt_private01" { vpc_id = "${aws_vpc.myvpc.id}" route { cidr_block = "0.0.0.0/0" nat_gateway_id = "${aws_nat_gateway.nat_gw01.id}" } tags { Name = "rt_private01" } } resource "aws_route_table" "rt_private02" { vpc_id = "${aws_vpc.myvpc.id}" route { cidr_block = "0.0.0.0/0" nat_gateway_id = "${aws_nat_gateway.nat_gw02.id}" } tags { Name = "rt_private02" } } resource "aws_route_table" "rt_private03" { vpc_id = "${aws_vpc.myvpc.id}" route { cidr_block = "0.0.0.0/0" nat_gateway_id = "${aws_nat_gateway.nat_gw03.id}" } tags { Name = "rt_private03" } } # Associate Subnet Private 01 with Route Table resource "aws_route_table_association" "rt_assoc_private01" { subnet_id = "${aws_subnet.subnet01-private.id}" route_table_id = "${aws_route_table.rt_private01.id}" } # Associate Subnet Private 02 with Route Table resource "aws_route_table_association" "rt_assoc_private02" { subnet_id = "${aws_subnet.subnet02-private.id}" route_table_id = "${aws_route_table.rt_private02.id}" } # Associate Subnet Private 03 with Route Table resource "aws_route_table_association" "rt_assoc_private03" { subnet_id = "${aws_subnet.subnet03-private.id}" route_table_id = "${aws_route_table.rt_private03.id}" }
- security_groups.tf
# Title: security_groups.tf # Description: Security groups for resources in subnets. ####-- Security Groups --#### # Create default locked down security groups for private and public subnets # Security Group: Public Subnets resource "aws_security_group" "sg_public_default" { name = "sg_public_default" description = "Default public facing security group" tags = { Name = "sg_public_default" } vpc_id = "${aws_vpc.myvpc.id}" ##-- Ingress/Inbound Rules --## # No ingress/inbound rules by default #ingress { #} ##-- Egress/Outbound Rules --## # Allow all egress/outbound traffic egress { from_port = 0 to_port = 0 protocol = "-1" cidr_blocks = ["0.0.0.0/0"] } } # Security Group: Private Subnets resource "aws_security_group" "sg_private_default" { name = "sg_private_default" description = "Default private facing security group" tags = { Name = "sg_private_default" } vpc_id = "${aws_vpc.myvpc.id}" ##-- Ingress/Inbound Rules --## # Allow all ssh traffic from default public security group ingress { from_port = 22 to_port = 22 protocol = "tcp" security_groups = ["${aws_security_group.sg_public_default.id}"] } # Allow all traffic within the private security group ingress { from_port = 0 to_port = 0 protocol = "-1" self = "true" } ##-- Egress/Outbound Rules --## # Allow all egress/outbound traffic egress { from_port = 0 to_port = 0 protocol = "-1" cidr_blocks = ["0.0.0.0/0"] } }
- outputs.tf
# Title: outputs.tf # Description: Outputs from resources saved as variables # Store the VPC ID - pulled from here in main's output.tf output "vpc_id" { value = "${aws_vpc.myvpc.id}" }