Rspec-Terraform

• Motivation
  • Looking Ahead
• Usage
  • Setup
  • Matchers
• Contributing

Motivation

Terraform is an awesome way of provisioning your infrastructure. However, like with any new tool, the ecosystem surrounding it is very immature. This can cause problems when sharing code or coming up against the rough edges of a tool in active development.

The creation of rspec-terraform was initially intended to smooth the creation and sharing of common Terraform modules. Some sort of basic testing would ensure a stable and clearly defined interface for each module.

Looking Ahead

Eventually, a two-tiered approach to testing would be ideal.

Provisioning non-trivial infrastructure should involve the use of many Terraform modules (rather than defining everything yourself). Taking AWS as an example, this might include VPCs, ASGs, SGs, public/private subnets etc. Each of these modules should be unit tested using rspec-terraform so that the interfaces they expose are well-defined.

Assembling many individual modules into a cohesive platform should also - ideally - be tested. It's unclear at this stage how this might look and is yet to be implemented. Something similar to serverspec may work.

Usage

As outlined above, only simple unit-test type operations are currently supported.

Setup

You will need Ruby and bundler installed.

Create a Gemfile at the root of your Terraform module and add the following:

source 'https://rubygems.org'

gem 'rspec-terraform'

Then install the gem:

bundle

Matchers

N.B. You must set the provider for each test. This is best done in the opening describe block:

describe 'tf-aws-vpc', provider: :aws do
  ...
end

At present, only the AWS provider is available.

The matchers currently implemented are:

1. require_variables

it 'expects the correct variables to be provided' do
 expected_variables = %w(vpccidr ec2nameserver region account envname domain)
 expect('terraform plan').to require_variables expected_variables
end

2. create_a_plan

it 'creates a plan' do
  expect('terraform plan -var-file example_variables/test_values.tfvars').to create_a_plan
end

Contributing

1. Fork it ( https://github.com/bsnape/rspec-terraform/fork )
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create a new Pull Request