Using Terraform with Google Cloud#

This guide shows you how to use Semaphore to set up a pipeline using Terraform with Google Cloud.

For this guide you will need:

Store credentials in secrets#

  • Store the Google Cloud credentials

Assuming that your Google Cloud credentials are stored on your computer in /home/<username>/.ssh/gcp.json use the following command to create a secret on Semaphore:

sem create secret gcp \
  -f /home/<username>/.ssh/gcp.json:.ssh/gcp.json
  • Create and store a deploy key
$ ssh-keygen -t rsa -b 4096
Generating public/private rsa key pair.
Enter file in which to save the key (/Users/admin/.ssh/id_rsa): /Users/admin/.ssh/id_rsa_semaphore_terraform
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /Users/admin/.ssh/id_rsa_semaphore_terraform.
Your public key has been saved in /Users/admin/.ssh/id_rsa_semaphore_terraform.pub.
The key fingerprint is:
SHA256:otdc9yDdLtmtkCJvt2uOdDH6yrLfa/BZBu6qtmvbRsY admin@example.com
The key's randomart image is:
+---[RSA 4096]----+
|                 |
|                 |
|                 |
|           ...   |
|      . S.o.*..  |
|     . + .E+.Xo. |
|    . . +o++*++ .|
|     .  +*o*Bo . |
|       o*@OBB+.  |
+----[SHA256]-----+

We need to make the private key id_rsa_semaphore_terraform available on Semaphore, and add the corresponding public key id_rsa_semaphore_terraform.pub to the Google Cloud project under Metadata/SSh keys

$ sem create secret terraform-key \
  --file /Users/admin/.ssh/id_rsa_semaphore_terraform:/home/semaphore/.ssh/id_rsa_semaphore_terraform
Secret 'terraform-key' created.

Define the Terraform configuration file#

provider "google" {
 credentials = file("~/.ssh/gcp.json")
 project     = "example-project"
 region      = "us-west1"
}
// Terraform plugin for creating random ids
resource "random_id" "instance_id" {
 byte_length = 8
}

// A single Compute Engine instance
resource "google_compute_instance" "default" {
 name         = "terraformvm-${random_id.instance_id.hex}"
 machine_type = "f1-micro"
 zone         = "us-west1-a"
metadata = {
   ssh-keys = "terraform:${file("~/.ssh/id_rsa_semaphore_terraform")}"
 }
 boot_disk {
   initialize_params {
     image = "debian-cloud/debian-9"
   }
 }

// Make sure flask is installed on all new instances for later steps
 metadata_startup_script = "sudo apt-get update; sudo apt-get install -yq nginx"

 network_interface {
   network = "default"

   access_config {
     // Include this section to give the VM an external ip address
   }
 }
}
output "ip" {
 value = google_compute_instance.default.network_interface.0.access_config.0.nat_ip
}

Define the pipeline#

Finally, let's define what happens in our semaphore.yml pipeline:

version: v1.0
name: Initial Pipeline
agent:
  machine:
    type: e1-standard-2
    os_image: ubuntu1804
blocks:
  - name: 'Init'
    task:
      secrets:
        - name: terraform-key
        - name: gcp
      jobs:
        - name: 'Init Terraform Gcloud'
          commands:
            - checkout
            - chmod 0600 ~/.ssh/id_rsa_semaphore_terraform
            - cd gcloud
            - terraform init
            - terraform plan
            - terraform apply -auto-approve
            - terraform show terraform.tfstate

Verify it works#

Push a new commit on any branch and open Semaphore to watch a new workflow run. If all goes well you'll see a Passed green box next to your pipeline indicating the workflow finished successfully.

Next steps#

Congratulations! You have created a successful pipeline that communicates Terraform with Google Cloud. Here’s some recommended reading: