Building VM images using Packer

Packer is an open source tool for creating identical Virtual Machine (VM) images for multiple platforms from a single source configuration. This page explains how to use Packer and Cloud Build to create a VM image for use on Compute Engine.

Before you begin

The instructions on this page assume that you are familiar with Packer. In addition:

  • Have your source code including the Packer template handy.
  • Have a Docker repository in Artifact Registry or create a new repository.
  • If you want to use the gcloud commands in this page, install the Google Cloud CLI.

  • Enable the following APIs:

    gcloud services enable compute.googleapis.com
gcloud services enable servicemanagement.googleapis.com
gcloud services enable storage-api.googleapis.com
gcloud services enable artifactregistry.googleapis.com

Required IAM permissions

Creating a Packer builder image

Cloud Build provides a Packer community builder image that you can use to invoke packer commands in Cloud Build. Before using this builder in a Cloud Build config file, you must build the image and push it to Artifact Registry:

  1. Clone the cloud-builders-community repository:

    git clone https://github.com/GoogleCloudPlatform/cloud-builders-community.git

  2. Navigate to the Packer builder image:

    cd cloud-builders-community/packer

  3. Submit the builder to your project:

    gcloud builds submit . --config cloudbuild.yaml --substitutions=_AR_HOST=[LOCATION]-docker.pkg.dev,_AR_REPO=[REPOSITORY]

    Where:

    • [LOCATION] is the region of your Artifact Registry repository.
    • [REPOSITORY] is the name of your Artifact Registry repository.

Creating a Packer template

Create a new file named packer.pkr.hcl and add the template configuration.

The following example shows a Packer template (packer.pkr.hcl) configured to build a Compute Engine VM image:

packer {
  required_plugins {
    googlecompute = {
      version = ">= 1.1.1"
      source  = "github.com/hashicorp/googlecompute"
    }
  }
}

variable "image_name" {
  type    = string
  description = "The name of the output VM image"
  default = "my-packer-image"
}
variable "project_id" {
  type    = string
  description = "The GCP project ID"
}
variable "image_family" {
  type    = string
  description = "The family of the output VM image"
  default = "my-image-family"
}
variable "image_zone" {
  type    = string
  description = "The zone to build the image in"
  default = "us-central1-a"
}

source "googlecompute" "gce" {
  project_id          = var.project_id
  source_image_family = "ubuntu-2004-lts"
  source_image_project_ids = ["ubuntu-os-cloud"]
  zone                = var.image_zone
  ssh_username        = "packer"
  machine_type        = "e2-small"
  image_name          = "${var.image_name}-"
  image_family        = var.image_family
}

build {
  name    = "gce-vm-image"
  sources = ["sources.googlecompute.gce"]

  provisioner "shell" {
    inline = [
      "echo 'Provisioning image...'",
      "sudo apt-get update",
      "sudo apt-get install -y nginx"
    ]
  }
}

Using the Packer builder

  1. Ensure that you have your Packer template (for example, packer.pkr.hcl) along with your source code.

  2. In your project root directory, create a build config file named cloudbuild.yaml or cloudbuild.json.

  3. In your build config file, add a build step to invoke the packer build command:

    YAML 

    steps:
- name: '[LOCATION]-docker.pkg.dev/[PROJECT_ID]/[REPOSITORY]/packer'
  args:
  - build
  - -var
  - image_name=[IMAGE_NAME]
  - -var
  - project_id=[PROJECT_ID]
  - -var
  - image_family=[IMAGE_FAMILY]
  - -var
  - image_zone=[IMAGE_ZONE]
  - packer.pkr.hcl

    JSON 

    {
  "steps": [
   {
      "name": "[LOCATION]-docker.pkg.dev/[PROJECT_ID]/[REPOSITORY]/packer",
      "args": [
        "build",
        "-var",
        "image_name=[IMAGE_NAME]",
        "-var",
        "project_id=[PROJECT_ID]",
        "-var",
        "image_family=[IMAGE_FAMILY]",
        "-var",
        "image_zone=[IMAGE_ZONE]",
        "packer.pkr.hcl"
       ]
    }
   ]
}

    Where:

    • [LOCATION] is the region of your Artifact Registry repository.
    • [PROJECT_ID] is your Google Cloud project ID.
    • [REPOSITORY] is the name of your Artifact Registry repository.
    • [IMAGE_NAME] is the name of the VM image you're building.
    • [IMAGE_FAMILY] is the image family of the VM image.
    • [IMAGE_ZONE] is the image zone.

  4. Start the build using the build config file:

    gcloud builds submit --region=[REGION] --config [CONFIG_FILE_PATH] [SOURCE_DIRECTORY]

    Where:

    • [CONFIG_FILE_PATH] is the path to the build config file.
    • [SOURCE_DIRECTORY] is the path or URL to the source code.
    • [REGION] is one of the supported build regions.

    If you don't specify a [CONFIG_FILE_PATH] and [SOURCE_DIRECTORY] in the gcloud builds submit command, Cloud Build assumes that the config file and the source code are in the current working directory.

Once the images are built, you can view them in the Compute Engine Image page in the Google Cloud console.

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