Terraform AWS ACM Certificate

A Terraform module to create and DNS validate an ACM certificate.

The certificate deployment depends on an existing Route53 hosted zone.

The certificate deployment consists of:

• an ACM certificate for the specified domain and SANs
• domain validation records fot the specified domain and all SANs

Usage

To use the module, include something like the following in your Terraform configuration:

module "acm_certificate" {
  source  = "infrablocks/acm-certificate/aws"
  version = "1.1.0"

  domain_name    = "*.${data.terraform_remote_state.domain.outputs.domain_name}"
  domain_zone_id = data.terraform_remote_state.domain.outputs.public_zone_id

  subject_alternative_names        = []
  subject_alternative_name_zone_id = data.terraform_remote_state.domain.outputs.public_zone_id

  providers = {
    aws.certificate       = aws
    aws.domain_validation = aws
    aws.san_validation    = aws
  }
}

See the Terraform registry entry for more details.

Inputs

Name	Description	Default	Required
domain_name	The domain name of the certificate to manage.	-	Yes
domain_zone_id	The ID of the hosted zone in which to manage domain validation records.	-	Yes
subject_alternative_names	The subject alternative names of the certificate to manage.	[]	No
subject_alternative_name_zone_id	The ID of the hosted zone in which to create subject alternative name validation records.	-	Yes

Outputs

Name	Description
certificate_arn	The ARN of the managed certificate.
domain_validations	A list of the domain validations that have been performed for the managed certificate.

Compatibility

This module is compatible with Terraform versions greater than or equal to Terraform 1.0.

Development

Machine Requirements

In order for the build to run correctly, a few tools will need to be installed on your development machine:

• Ruby (3.1)
• Bundler
• git
• git-crypt
• gnupg
• direnv
• aws-vault

Mac OS X Setup

Installing the required tools is best managed by homebrew.

To install homebrew:

ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"

Then, to install the required tools:

# ruby
brew install rbenv
brew install ruby-build
echo 'eval "$(rbenv init - bash)"' >> ~/.bash_profile
echo 'eval "$(rbenv init - zsh)"' >> ~/.zshrc
eval "$(rbenv init -)"
rbenv install 3.1.1
rbenv rehash
rbenv local 3.1.1
gem install bundler

# git, git-crypt, gnupg
brew install git
brew install git-crypt
brew install gnupg

# aws-vault
brew cask install

# direnv
brew install direnv
echo "$(direnv hook bash)" >> ~/.bash_profile
echo "$(direnv hook zsh)" >> ~/.zshrc
eval "$(direnv hook $SHELL)"

direnv allow <repository-directory>

Running the build

Running the build requires an AWS account and AWS credentials. You are free to configure credentials however you like as long as an access key ID and secret access key are available. These instructions utilise aws-vault which makes credential management easy and secure.

To run the full build, including unit and integration tests, execute:

aws-vault exec <profile> -- ./go

To run the unit tests, execute:

aws-vault exec <profile> -- ./go test:unit

To run the integration tests, execute:

aws-vault exec <profile> -- ./go test:integration

To provision the module prerequisites:

aws-vault exec <profile> -- ./go deployment:prerequisites:provision[<deployment_identifier>]

To provision the module contents:

aws-vault exec <profile> -- ./go deployment:root:provision[<deployment_identifier>]

To destroy the module contents:

aws-vault exec <profile> -- ./go deployment:root:destroy[<deployment_identifier>]

To destroy the module prerequisites:

aws-vault exec <profile> -- ./go deployment:prerequisites:destroy[<deployment_identifier>]

Configuration parameters can be overridden via environment variables. For example, to run the unit tests with a seed of "testing", execute:

SEED=testing aws-vault exec <profile> -- ./go test:unit

When a seed is provided via an environment variable, infrastructure will not be destroyed at the end of test execution. This can be useful during development to avoid lengthy provision and destroy cycles.

To subsequently destroy unit test infrastructure for a given seed:

FORCE_DESTROY=yes SEED=testing aws-vault exec <profile> -- ./go test:unit

Common Tasks

Generating an SSH key pair

To generate an SSH key pair:

ssh-keygen -m PEM -t rsa -b 4096 -C integration-test@example.com -N '' -f config/secrets/keys/bastion/ssh

Generating a self-signed certificate

To generate a self signed certificate:

openssl req -x509 -newkey rsa:4096 -keyout key.pem -out cert.pem -days 365

To decrypt the resulting key:

openssl rsa -in key.pem -out ssl.key

Managing CircleCI keys

To encrypt a GPG key for use by CircleCI:

openssl aes-256-cbc \
  -e \
  -md sha1 \
  -in ./config/secrets/ci/gpg.private \
  -out ./.circleci/gpg.private.enc \
  -k "<passphrase>"

To check decryption is working correctly:

openssl aes-256-cbc \
  -d \
  -md sha1 \
  -in ./.circleci/gpg.private.enc \
  -k "<passphrase>"

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/infrablocks/terraform-aws-acm-certificate. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.

License

The library is available as open source under the terms of the MIT License.