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The googlecompute plugin can be used with HashiCorp Packer to create custom images on GCE.

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Updated 2 years ago

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Google Cloud Platform

The Google compute Packer plugin lets you create custom images for use within Google Compute Engine (GCE).

Installation

To install this plugin, copy and paste this code into your Packer configuration, then run packer init.

packer {
  required_plugins {
    googlecompute = {
      source  = "github.com/hashicorp/googlecompute"
      version = "~> 1"
    }
  }
}

Alternatively, you can use packer plugins install to manage installation of this plugin.

$ packer plugins install github.com/hashicorp/googlecompute

Components

Builders

googlecompute - The googlecompute builder creates images from existing ones, by launching an instance, provisioning it, then exporting it as a reusable image.

Post-Processors

googlecompute-import - The googlecompute-import post-processor imports an existing raw disk image, and imports it as a GCE image that can be used for launching instances from.
googlecompute-export - The googlecompute-export post-processor exports the image built by the googlecompute builder as a .tar.gz archive into Google Cloud Storage (GCS).

Authentication

Authenticating with Google Cloud services requires either a User Application Default Credentials, a JSON Service Account Key or an Access Token. These are not required if you are running the googlecompute Packer builder on Google Cloud with a properly-configured Google Service Account.

The following options are available for the googlecompute builder, the googlecompute-export, and thegooglecompute-import`:

access_token (string) - A temporary OAuth 2.0 access token obtained from the Google Authorization server, i.e. the Authorization: Bearer token used to authenticate HTTP requests to GCP APIs. This is an alternative to account_file, and ignores the scopes field. If both are specified, access_token will be used over the account_file field.
These access tokens cannot be renewed by Packer and thus will only work until they expire. If you anticipate Packer needing access for longer than a token's lifetime (default 1 hour), please use a service account key with account_file instead.
account_file (string) - The JSON file containing your account credentials. Not required if you run Packer on a GCE instance with a service account. Instructions for creating the file or using service accounts are above.
credentials_file (string) - The JSON file containing your account credentials.
The file's contents may be anything supported by the Google Go client, i.e.:
- Service account JSON
- OIDC-provided token for federation
- Gcloud user credentials file (refresh-token JSON)
- A Google Developers Console client_credentials.json
credentials_json (string) - The raw JSON payload for credentials.
The accepted data formats are same as those described under credentials_file.
impersonate_service_account (string) - This allows service account impersonation as per the docs.
vault_gcp_oauth_engine (string) - Can be set instead of account_file. If set, this builder will use HashiCorp Vault to generate an Oauth token for authenticating against Google Cloud. The value should be the path of the token generator within vault. For information on how to configure your Vault + GCP engine to produce Oauth tokens, see https://www.vaultproject.io/docs/auth/gcp You must have the environment variables VAULT_ADDR and VAULT_TOKEN set, along with any other relevant variables for accessing your vault instance. For more information, see the Vault docs: https://www.vaultproject.io/docs/commands/#environment-variables Example:"vault_gcp_oauth_engine": "gcp/token/my-project-editor",

Running locally on your workstation.

If you run the googlecompute Packer builder locally on your workstation, you will need to install the Google Cloud SDK and authenticate using User Application Default Credentials. You don't need to specify an account file if you are using this method. Your user must have at least Compute Instance Admin (v1) & Service Account User roles to use Packer succesfully.

Running on Google Cloud

If you run the googlecompute Packer builder on GCE or GKE, you can configure that instance or cluster to use a Google Service Account. This will allow Packer to authenticate to Google Cloud without having to bake in a separate credential/authentication file.

It is recommended that you create a custom service account for Packer and assign it Compute Instance Admin (v1) & Service Account User roles.

For gcloud, you can run the following commands:

$ gcloud iam service-accounts create packer \
  --project YOUR_GCP_PROJECT \
  --description="Packer Service Account" \
  --display-name="Packer Service Account"

$ gcloud projects add-iam-policy-binding YOUR_GCP_PROJECT \
    --member=serviceAccount:packer@YOUR_GCP_PROJECT.iam.gserviceaccount.com \
    --role=roles/compute.instanceAdmin.v1

$ gcloud projects add-iam-policy-binding YOUR_GCP_PROJECT \
    --member=serviceAccount:packer@YOUR_GCP_PROJECT.iam.gserviceaccount.com \
    --role=roles/iam.serviceAccountUser

$ gcloud projects add-iam-policy-binding YOUR_GCP_PROJECT \
    --member=serviceAccount:packer@YOUR_GCP_PROJECT.iam.gserviceaccount.com \
    --role=roles/iap.tunnelResourceAccessor

$ gcloud compute instances create INSTANCE-NAME \
  --project YOUR_GCP_PROJECT \
  --image-family ubuntu-2004-lts \
  --image-project ubuntu-os-cloud \
  --network YOUR_GCP_NETWORK \
  --zone YOUR_GCP_ZONE \
  --service-account=packer@YOUR_GCP_PROJECT.iam.gserviceaccount.com \
  --scopes="https://www.googleapis.com/auth/cloud-platform"

The service account will be used automatically by Packer as long as there is no account file specified in the Packer configuration file.

Running outside of Google Cloud

The Google Cloud Console allows you to create and download a credential file that will let you use the googlecompute Packer builder anywhere. To make the process more straightforwarded, it is documented here.

Log into the Google Cloud Console and select a project.
Click Select a project, choose your project, and click Open.
Click Create Service Account.
Enter a service account name (friendly display name), an optional description, select the Compute Engine Instance Admin (v1) and Service Account User roles, and then click Save.
Generate a JSON Key and save it in a secure location.
Set the Environment Variable GOOGLE_APPLICATION_CREDENTIALS to point to the path of the service account key.

Precedence of Authentication Methods

Packer looks for credentials in the following places, preferring the first location found:

An access_token option in your packer file.
An account_file option in your packer file.
A JSON file (Service Account) whose path is specified by the GOOGLE_APPLICATION_CREDENTIALS environment variable.
A JSON file in a location known to the gcloud command-line tool. (gcloud auth application-default login creates it)
On Windows, this is:
```
%APPDATA%/gcloud/application_default_credentials.json
```
On other systems:
```
$HOME/.config/gcloud/application_default_credentials.json
```
On Google Compute Engine and Google App Engine Managed VMs, it fetches credentials from the metadata server. (Needs a correct VM authentication scope configuration, see above.)

Examples

Basic Example

Below is a fully functioning example. It doesn't do anything useful since no provisioners or startup-script metadata are defined, but it will effectively repackage an existing GCE image.

JSON

{
  "builders": [
    {
      "type": "googlecompute",
      "project_id": "my project",
      "source_image": "debian-9-stretch-v20200805",
      "ssh_username": "packer",
      "zone": "us-central1-a"
    }
  ]
}

HCL2

source "googlecompute" "basic-example" {
  project_id = "my project"
  source_image = "debian-9-stretch-v20200805"
  ssh_username = "packer"
  zone = "us-central1-a"
}

build {
  sources = ["sources.googlecompute.basic-example"]
}

Windows Example

Before you can provision using the winrm communicator, you need to allow traffic through google's firewall on the winrm port (tcp:5986). You can do so using the gcloud command.

gcloud compute firewall-rules create allow-winrm --allow tcp:5986

Or alternatively by navigating to https://console.cloud.google.com/networking/firewalls/list.

Once this is set up, the following is a complete working packer config after setting a valid project_id:

JSON

{
  "builders": [
    {
      "type": "googlecompute",
      "project_id": "my project",
      "source_image": "windows-server-2019-dc-v20200813",
      "disk_size": "50",
      "machine_type": "n1-standard-2",
      "communicator": "winrm",
      "winrm_username": "packer_user",
      "winrm_insecure": true,
      "winrm_use_ssl": true,
      "metadata": {
        "sysprep-specialize-script-cmd": "winrm quickconfig -quiet & net user /add packer_user & net localgroup administrators packer_user /add & winrm set winrm/config/service/auth @{Basic=\"true\"}"
      },
      "zone": "us-central1-a"
    }
  ]
}

HCL2

source "googlecompute" "windows-example" {
  project_id = "MY_PROJECT"
  source_image = "windows-server-2019-dc-v20200813"
  zone = "us-central1-a"
  disk_size = 50
  machine_type = "n1-standard-2"
  communicator = "winrm"
  winrm_username = "packer_user"
  winrm_insecure = true
  winrm_use_ssl = true
  metadata = {
    sysprep-specialize-script-cmd = "winrm quickconfig -quiet & net user /add packer_user & net localgroup administrators packer_user /add & winrm set winrm/config/service/auth @{Basic=\"true\"}"
  }
}

build {
  sources = ["sources.googlecompute.windows-example"]
}

Warning: Please note that if you're setting up WinRM for provisioning, you'll probably want to turn it off or restrict its permissions as part of a shutdown script at the end of Packer's provisioning process. For more details on the why/how, check out this useful blog post and the associated code: https://missionimpossiblecode.io/post/winrm-for-provisioning-close-the-door-on-the-way-out-eh/

This build can take up to 15 min.

Windows over WinSSH Example

The following uses Windows SSH as backend communicator https://docs.microsoft.com/en-us/windows-server/administration/openssh/openssh_install_firstuse

source "googlecompute" "windows-ssh-example" {
  project_id = "MY_PROJECT"
  source_image = "windows-server-2019-dc-v20200813"
  zone = "us-east4-a"
  disk_size = 50
  machine_type = "n1-standard-2"
  communicator = "ssh"
  ssh_username = var.packer_username
  ssh_password = var.packer_user_password
  ssh_timeout = "1h"
  metadata = {
    sysprep-specialize-script-cmd = "net user ${var.packer_username} \"${var.packer_user_password}\" /add /y & wmic UserAccount where Name=\"${var.packer_username}\" set PasswordExpires=False & net localgroup administrators ${var.packer_username} /add & powershell Add-WindowsCapability -Online -Name OpenSSH.Server~~~~0.0.1.0 & powershell Start-Service sshd & powershell Set-Service -Name sshd -StartupType 'Automatic' & powershell New-NetFirewallRule -Name 'OpenSSH-Server-In-TCP' -DisplayName 'OpenSSH Server (sshd)' -Enabled True -Direction Inbound -Protocol TCP -Action Allow -LocalPort 22 & powershell.exe -NoProfile -ExecutionPolicy Bypass -Command \"Set-ExecutionPolicy -ExecutionPolicy bypass -Force\""
  }
}

build {
  sources = ["sources.googlecompute.windows-ssh-example"]

  provisioner "powershell" {
    script = "../scripts/install-features.ps1"
    elevated_user     = var.packer_username
    elevated_password = var.packer_user_password
  }
}

Windows over WinSSH - Ansible Provisioner

The following uses Windows SSH as backend communicator https://docs.microsoft.com/en-us/windows-server/administration/openssh/openssh_install_firstuse with a private key.

The sysprep-specialize-script-cmd creates the packer_user and adds it to the local administrators group and configures the ssh key, firewall rule and required permissions.

source "googlecompute" "windows-ssh-ansible" {
  project_id              = var.project_id
  source_image            = "windows-server-2019-dc-v20200813"
  zone                    = "us-east4-a"
  disk_size               = 50
  machine_type            = "n1-standard-8"
  communicator            = "ssh"
  ssh_username            = var.packer_username
  ssh_private_key_file    = var.ssh_key_file_path
  ssh_timeout             = "1h"
  
  metadata = {
    sysprep-specialize-script-cmd = "net user ${var.packer_username} \"${var.packer_user_password}\" /add /y & wmic UserAccount where Name=\"${var.packer_username}\" set PasswordExpires=False & net localgroup administrators ${var.packer_username} /add & powershell Add-WindowsCapability -Online -Name OpenSSH.Server~~~~0.0.1.0 & echo ${var.ssh_pub_key} > C:\\ProgramData\\ssh\\administrators_authorized_keys & icacls.exe \"C:\\ProgramData\\ssh\\administrators_authorized_keys\" /inheritance:r /grant \"Administrators:F\" /grant \"SYSTEM:F\" & powershell New-ItemProperty -Path \"HKLM:\\SOFTWARE\\OpenSSH\" -Name DefaultShell -Value \"C:\\Windows\\System32\\WindowsPowerShell\\v1.0\\powershell.exe\" -PropertyType String -Force  & powershell Start-Service sshd & powershell Set-Service -Name sshd -StartupType 'Automatic' & powershell New-NetFirewallRule -Name 'OpenSSH-Server-In-TCP' -DisplayName 'OpenSSH Server (sshd)' -Enabled True -Direction Inbound -Protocol TCP -Action Allow -LocalPort 22 & powershell.exe -NoProfile -ExecutionPolicy Bypass -Command \"Set-ExecutionPolicy -ExecutionPolicy bypass -Force\""
  }
  account_file = var.account_file_path

}

build {
  sources = ["sources.googlecompute.windows-ssh-ansible"]

  provisioner "ansible" {
    playbook_file           = "./playbooks/playbook.yml"
    use_proxy               = false
    ansible_ssh_extra_args  = ["-o StrictHostKeyChecking=no -o IdentitiesOnly=yes"]
    ssh_authorized_key_file = "var.public_key_path"
    extra_arguments = ["-e", "win_packages=${var.win_packages}",
      "-e",
      "ansible_shell_type=powershell",
      "-e",
      "ansible_shell_executable=None",
      "-e",
      "ansible_shell_executable=None"
    ]
    user = var.packer_username
  }

}

Nested Hypervisor Example

This is an example of using the image_licenses configuration option to create a GCE image that has nested virtualization enabled. See Enabling Nested Virtualization for VM Instances for details.

JSON

{
  "builders": [
    {
      "type": "googlecompute",
      "project_id": "my project",
      "source_image_family": "centos-7",
      "ssh_username": "packer",
      "zone": "us-central1-a",
      "image_licenses": ["projects/vm-options/global/licenses/enable-vmx"]
    }
  ]
}

HCL2

source "googlecompute" "basic-example" {
  project_id = "my project"
  source_image_family = "centos-7"
  ssh_username = "packer"
  zone = "us-central1-a"
  image_licenses = ["projects/vm-options/global/licenses/enable-vmx"]
}

build {
  sources = ["sources.googlecompute.basic-example"]
}

Shared VPC Example

This is an example of using the network_project_id configuration option to create a GCE instance in a Shared VPC Network. See Creating a GCE Instance using Shared VPC for details. The user/service account running Packer must have Compute Network User role on the Shared VPC Host Project to create the instance in addition to the other roles mentioned in the Running on Google Cloud section.

JSON

{
  "builders": [
    {
      "type": "googlecompute",
      "project_id": "my project",
      "subnetwork": "default",
      "source_image_family": "centos-7",
      "network_project_id": "SHARED_VPC_PROJECT",
      "ssh_username": "packer",
      "zone": "us-central1-a",
      "image_licenses": ["projects/vm-options/global/licenses/enable-vmx"]
    }
  ]
}

HCL2

source "googlecompute" "sharedvpc-example" {
  project_id = "my project"
  source_image_family = "centos-7"
  subnetwork = "default"
  network_project_id = "SHARED_VPC_PROJECT"
  ssh_username = "packer"
  zone = "us-central1-a"
  image_licenses = ["projects/vm-options/global/licenses/enable-vmx"]
}

build {
  sources = ["sources.googlecompute.sharedvpc-example"]
}

Separate Image Project Example

This is an example of using the image_project_id configuration option to create the generated image in a different GCP project than the one used to create the virtual machine. Make sure that Packer has permission in the target project to manage images, the Compute Storage Admin role will grant the desired permissions.

JSON

{
  "builders": [
    {
      "type": "googlecompute",
      "project_id": "my project",
      "image_project_id": "my image target project",
      "source_image": "debian-9-stretch-v20200805",
      "ssh_username": "packer",
      "zone": "us-central1-a"
    }
  ]
}

HCL2

source "googlecompute" "basic-example" {
  project_id = "my project"
  image_project_id = "my image target project"
  source_image = "debian-9-stretch-v20200805"
  ssh_username = "packer"
  zone = "us-central1-a"
}

build {
  sources = ["sources.googlecompute.basic-example"]
}