Terraform Scripts

Install

brew install terraform

brew install ansible
brew install terraform-inventory

Prerequisite

1. Create ~/.aws/credentials. Obtain keys from Profile -> "My Security Credentials"

[default]
aws_access_key_id=<access_key_id>
aws_secret_access_key=<secret>

2. Create or copy a public-private key pair to access instances to ~/.ssh/terraform.pub

ssh-keygen -f ~/.ssh/terraform

3. Create terraform.tfvars

cloudflare_email="<cloudflare_email>"
cloudflare_token="<cloudflare_token>" # From My Profile -> API Keys
do_token="<digital_ocean_token>" # From Manage -> API -> Tokens

Usage

1. terraform init. This will download plugins needed.
2. terraform apply. Will create/update/destroy EC2 instances as defined in main.tf

First execution plan will be shown

An execution plan has been generated and is shown below.
Resource actions are indicated with the following symbols:
  + create

Terraform will perform the following actions:

  + aws_vpc.default
      id:                               <computed>
      arn:                              <computed>
      assign_generated_ipv6_cidr_block: "false"
      cidr_block:                       "10.0.0.0/16"
      default_network_acl_id:           <computed>
      default_route_table_id:           <computed>
      default_security_group_id:        <computed>
      dhcp_options_id:                  <computed>
      enable_classiclink:               <computed>
      enable_classiclink_dns_support:   <computed>
      enable_dns_hostnames:             <computed>
      enable_dns_support:               "true"
      instance_tenancy:                 "default"
      ipv6_association_id:              <computed>
      ipv6_cidr_block:                  <computed>
      main_route_table_id:              <computed>


Plan: 1 to add, 0 to change, 0 to destroy.

Do you want to perform these actions?
  Terraform will perform the actions described above.
  Only 'yes' will be accepted to approve.

  Enter a value: 

Then it is applied after keyboard confirmation

  Enter a value: yes

aws_vpc.default: Creating...
  arn:                              "" => "<computed>"
  assign_generated_ipv6_cidr_block: "" => "false"
  cidr_block:                       "" => "10.0.0.0/16"
  default_network_acl_id:           "" => "<computed>"
  default_route_table_id:           "" => "<computed>"
  default_security_group_id:        "" => "<computed>"
  dhcp_options_id:                  "" => "<computed>"
  enable_classiclink:               "" => "<computed>"
  enable_classiclink_dns_support:   "" => "<computed>"
  enable_dns_hostnames:             "" => "<computed>"
  enable_dns_support:               "" => "true"
  instance_tenancy:                 "" => "default"
  ipv6_association_id:              "" => "<computed>"
  ipv6_cidr_block:                  "" => "<computed>"
  main_route_table_id:              "" => "<computed>"
[aws_vpc.default: Creation complete after 6s (ID: vpc-080051c8aaca21b68)

Apply complete! Resources: 1 added, 0 changed, 0 destroyed.

Outputs:

example01-ip = 44.252.122.77

Outputs we see are what is defined in the output block in main.tf

3. ssh to the instance

We can query for it or use in the ssh script to the instance, or use DNS entry created by cloudflare.

❯❯❯ terraform output example01-ip
44.252.122.77
❯❯❯ ssh -i ~/.ssh/terraform ubuntu@`terraform output example01-ip`

### DNS should work after a while
❯❯❯ ssh -i ~/.ssh/terraform [email protected]

4. State of the execution is kept in terraform.tfstate.*. Check this in a repository to share system state with others.

Notes on using Ansible with Terraform

• Ansible dynamic scripts downloaded from https://github.com/adammck/terraform-inventory via brew
• Put it as default inventory source via ansible.cfg
• ansible.cfg is configured to read files in inventory/ as inventory file, so we need to symlink from /usr/local/bin/terraform-inventory

 ❯❯❯ ansible all --list-hosts
  hosts (1):
    35.165.28.244

 ❯❯❯ ansible role_example --list-hosts
  hosts (1):
    35.165.28.244

 ❯❯❯ ansible-playbook playbooks/example.yml

PLAY [role_example] *********************************

TASK [Gathering Facts] ******************************
ok: [35.162.30.126]

TASK [ufw : Enable Firewall and allow SSH] **********
changed: [35.162.30.126]

PLAY RECAP ******************************************
35.162.30.126              : ok=2    changed=1    unreachable=0    failed=0  

Reference

• https://github.com/terraform-providers/terraform-provider-aws/tree/master/examples/two-tier
• https://docs.aws.amazon.com/cli/latest/userguide/cli-config-files.html
• https://cloud-images.ubuntu.com/locator/ec2/
• https://github.com/adammck/terraform-inventory
• https://www.digitalocean.com/community/tutorials/how-to-install-nginx-on-ubuntu-18-04