terraform-inventory/README.md

Terraform Inventory

This is a little Go app which generates an dynamic Ansible ansible inventory from a [Terraform] tf state file. It allows one to spawn a bunch of instances with Terraform, then (re-)provision them with Ansible. Currently, only AWS, DigitalOcean, CloudStack, VMware, OpenStack, Google Compute Engine are supported.

Installation

On OSX, install it with Homebrew:

brew install https://raw.github.com/adammck/terraform-inventory/master/homebrew/terraform-inventory.rb

This is only a tiny tool, so it's not in the main Homebrew repo. Feel free to add it, if you think that would be useful.

Alternatively, you can download a release suitable to your platform and unzip it. Make sure the terraform-inventory binary is executable and you're ready to go.

Usage

If your Terraform state file is named terraform.tfstate (the default), cd to it and run:

ansible-playbook --inventory-file=terraform-inventory deploy/playbook.yml

This will provide the resource names and IP addresses of any instances found in the state file to Ansible, which can then be used as hosts patterns in your playbooks. For example, given for the following Terraform config:

resource "digitalocean_droplet" "my_web_server" {
  image = "centos-7-0-x64"
  name = "web-1"
  region = "nyc1"
  size = "512mb"
}

The corresponding playbook might look like:

- hosts: my_web_server
  tasks:
    - yum: name=cowsay
    - command: cowsay hello, world!

Note that the instance was identified by its resource name from the Terraform config, not its instance name from the provider. On AWS, resources are also grouped by their tags. For example:

resource "aws_instance" "my_web_server" {
  instance_type = "t2.micro"
  ami = "ami-96a818fe"
  tags = {
    Role = "web"
    Env = "dev"
  }
}

resource "aws_instance" "my_worker" {
  instance_type = "t2.micro"
  ami = "ami-96a818fe"
  tags = {
    Role = "worker"
    Env = "dev"
  }
}

Can be provisioned separately with:

- hosts: role_web
  tasks:
    - command: cowsay this is a web server!

- hosts: role_worker
  tasks:
    - command: cowsay this is a worker server!

- hosts: env_dev
  tasks:
    - command: cowsay this runs on all dev servers!

More Usage

Ansible doesn't seem to support calling a dynamic inventory script with params, so if you need to specify the location of your state file, set the TF_STATE environment variable before running ansible-playbook, like:

TF_STATE=deploy/terraform.tfstate ansible-playbook --inventory-file=terraform-inventory deploy/playbook.yml

Alternately, if you need to do something fancier (like downloading your state file from S3 before running), you might wrap this tool with a shell script, and call that instead. Something like:

#!/bin/bash
terraform-inventory $@ deploy/terraform.tfstate

Then run Ansible with the script as an inventory:

ansible-playbook --inventory-file=bin/inventory deploy/playbook.yml

Development

It's just a Go app, so the usual:

go get github.com/adammck/terraform-inventory

To test against an example statefile, run:

terraform-inventory --list fixtures/example.tfstate
terraform-inventory --host=52.7.58.202 fixtures/example.tfstate

To update the fixtures, populate fixtures/secrets.tfvars with your DO and AWS account details, and run fixtures/update. To run a tiny Ansible playbook on the example resourecs, run:

TF_STATE=fixtures/example.tfstate ansible-playbook --inventory-file=terraform-inventory fixtures/playbook.yml

You almost certainly don't need to do any of this. Use the tests instead.

Acknowledgements

Development of #14, #16, and #22 was generously sponsored by Transloadit.

License

MIT.