autoscaling-group-basic

Terraform sample code which builds a basic autoscaling group (ASG) in the EU-WEST-1 region across all 3 availability zones (AZ). The ASG has a min and max of 1 so it will always launch a single EC2 instance. It spans 3 public subnets having map_public_ip_on_launch set to true so the instance will have its own public IP. The EC2 instance is protected by a security group which by default allows SSH from the VPC CIDR range and your computer public IP.

Supported Cloud Providers: Amazon

OS utilized by the EC2 instance: Ubuntu 16.04 LTS x64

Requirements

• AWS account : valid AWS keys
• Terraform : terraform available in the search path

How to use

Simply run build-master-node.sh script on you have configured your AWS keys and have terraform available in the search path. Alternatively, cd terraform and run . ./files/remote-state.sh followed by terraform plan ., terraform apply . and terraform remote push (first you will have to export AWS keys as local variables for terraform to use them)

See below for more details on usage.

Terraform actions

• build a VPC in eu-west-1 region
• dns_hostnames enabled in the VPC
• uploads ssh key to be used by the ec2 instance
• 1 public route table; default route uses internet gateway; it is the main route in the VPC
• 3 public subnets; public IP allocation enabled; associated with the public route table
• 1 security group associated with the EC2 instance allowing:
  • SSH from the VPC cidr range and your computer public IP address
  • All outboud access

Terraform prep:

Create your ssh key files and add to secrets/ssh/. Use these file names: key_name=vpc_name, pub_key=vpc_name.pub. Add AWS keys to secrets/aws/creds.sh file. Create an S3 bucket in your AWS account for terraform to store the state. The bucket name has to be updated in terraform/files/remote-state.sh (for example: -backend-config="bucket=mue-masternode-terraform-04b062a1-0cad-46a7-ba24-6fdc0484e1f3" ). Open terraform/vars.tf to review and update defaults if needed (if you wish to use different VPC name or IP ranges; default VPC name: VPC01; default cidr range: 192.168.0.0/20)

Provisioning: Run build-master-node.sh to provision the infrastructure. This script will:

• source secrets/aws/creds.sh to set terraform environment variables
• configure and pull remote terrafrom state
• execute terraform plan
• ask if you wish to run terrafrom apply if planning goes without errors
• execute terraform apply if decided to do so
• unsets terrafrom environment variables as a last step

Destroying: Run destroy-master-node.sh to destroy all provisioned infrastructure in AWS.

Terraform vars Run ``

File terraform\vars.tf contains variables used for our infrastructure. The most important are:

• vpc name
• vpc cidr block
• subnets cidr ranges
• addittional IPs for allowing SSH access (default overriden via terraform.tfvars)

Folders

• terraform: terraform code, files split by function
• secrets : holds the ssh key and AWS creds file used by terraform