Create Terraform Enterprise Runs

Once an image is built and uploaded to an artifact store, the next step is to use this new image. In some cases the image will be downloaded by the dev team and used locally in development, like is often done with VirtualBox images with Vagrant. In most other cases, the new image will be used to provision new infrastructure.

Terraform is an open source tool that is ideal for provisioning new infrastructure with images generated by Packer, and Terraform Enterprise is the best way to perform automated Terraform runs.

Create a Terraform Configuration and Workspace

The following is a sample Terraform configuration which provisions a new AWS EC2 instance. The aws_ami_id is a variable which will be provided when running terraform plan and terraform apply. This variable references the latest AMI generated with the Packer build in CI/CD.

variable "aws_ami_id" { }

provider "aws" {
  region = "us-west-2"
}

resource "aws_instance" "web" {
  ami           = "${var.aws_ami_id}"
  instance_type = "t2.micro"
}

Terraform Enterprise should have a workspace with this terraform configuration and a placeholder variable aws_ami_id.

Include Terraform Enterprise in Your CI Builds

Follow these steps to create a new run from CI/CD after a Packer build is complete and uploaded.

1. Add a new step to the CI/CD pipeline.
2. In the new step add a curl call to update the variables in the workspace using the update variables API, so that Terraform has a reference to the latest image. For the sample configuration above, the aws_ami_id variable should be updated to the AMI ID of the latest image.
3. In that same step, add another curl call to create a new run via the API. A run performs a plan and apply on the last configuration version created, using the variables set in the workspace. In the previous step we update the variables, so the new run can be created using the previous configuration version.