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The googlecompute Packer builder is able to create images for use with Google Cloud Compute Engine (GCE) based on existing images.	docs	Google Compute - Builders	docs-builders-googlecompute

Google Compute Builder

Type: googlecompute

The googlecompute Packer builder is able to create images for use with Google Compute Engine(GCE) based on existing images. Building GCE images from scratch is not possible from Packer at this time. For building images from scratch, please see Building GCE Images from Scratch.

Authentication

Authenticating with Google Cloud services requires at most one JSON file, called the account file. The account file is not required if you are running the googlecompute Packer builder from a GCE instance with a properly-configured Compute Engine Service Account.

Running With a Compute Engine Service Account

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

To create a GCE instance that uses a service account, provide the required scopes when launching the instance.

For gcloud, do this via the --scopes parameter:

$ gcloud compute --project YOUR_PROJECT instances create "INSTANCE-NAME" ... \
    --scopes "https://www.googleapis.com/auth/compute,https://www.googleapis.com/auth/devstorage.full_control" \

For the Google Developers Console:

Choose "Show advanced options"
Tick "Enable Compute Engine service account"
Choose "Read Write" for Compute
Chose "Full" for "Storage"

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

Running Without a Compute Engine Service Account

The Google Developers 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 Developers Console and select a project.
Under the "API Manager" section, click "Credentials."
Click the "Create credentials" button, select "Service account key"
Create new service account that at least has Compute Engine Instance Admin (v1) and Service Account User roles.
Chose JSON as Key type and click "Create". A JSON file will be downloaded automatically. This is your account file.

Precedence of Authentication Methods

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

A 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 creates it when it's configured)

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)

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. The account_file is obtained in the previous section. If it parses as JSON it is assumed to be the file itself, otherwise it is assumed to be the path to the file containing the JSON.

{
  "builders": [
    {
      "type": "googlecompute",
      "account_file": "account.json",
      "project_id": "my project",
      "source_image": "debian-7-wheezy-v20150127",
      "zone": "us-central1-a"
    }
  ]
}

Windows Example

Running WinRM requires that it is opened in the firewall and that the VM enables WinRM for the user used to connect in a startup-script.

{
  "builders": [{
    "type": "googlecompute",
    "account_file": "account.json",
    "project_id": "my project",
    "source_image": "windows-server-2016-dc-v20170227",
    "disk_size": "50",
    "machine_type": "n1-standard-1",
    "communicator": "winrm",
    "winrm_username": "packer_user",
    "winrm_insecure": true,
    "winrm_use_ssl": true,
    "metadata": {
      "windows-startup-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"
  }]
}

Configuration Reference

Configuration options are organized below into two categories: required and optional. Within each category, the available options are alphabetized and described.

In addition to the options listed here, a communicator can be configured for this builder.

Required:

project_id (string) - The project ID that will be used to launch instances and store images.
source_image (string) - The source image to use to create the new image from. You can also specify source_image_family instead. If both source_image and source_image_family are specified, source_image takes precedence. Example: "debian-8-jessie-v20161027"
source_image_family (string) - The source image family to use to create the new image from. The image family always returns its latest image that is not deprecated. Example: "debian-8".
zone (string) - The zone in which to launch the instance used to create the image. Example: "us-central1-a"

Optional:

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 file or using service accounts are above.
address (string) - The name of a pre-allocated static external IP address. Note, must be the name and not the actual IP address.
disk_name (string) - The name of the disk, if unset the instance name will be used.
disk_size (integer) - The size of the disk in GB. This defaults to 10, which is 10GB.
disk_type (string) - Type of disk used to back your instance, like pd-ssd or pd-standard. Defaults to pd-standard.
image_description (string) - The description of the resulting image.
image_family (string) - The name of the image family to which the resulting image belongs. You can create disks by specifying an image family instead of a specific image name. The image family always returns its latest image that is not deprecated.
image_name (string) - The unique name of the resulting image. Defaults to "packer-{{timestamp}}".
instance_name (string) - A name to give the launched instance. Beware that this must be unique. Defaults to "packer-{{uuid}}".
machine_type (string) - The machine type. Defaults to "n1-standard-1".
metadata (object of key/value strings) - Metadata applied to the launched instance.
network (string) - The Google Compute network id or URL to use for the launched instance. Defaults to "default".
network_project_id (string) - The project ID for the network and subnetwork to use for launched instance. Defaults to project_id.
omit_external_ip (boolean) - If true, the instance will not have an external IP. use_internal_ip must be true if this property is true.
on_host_maintenance (string) - Sets Host Maintenance Option. Valid choices are MIGRATE and TERMINATE. Please see GCE Instance Scheduling Options, as not all machine_types support MIGRATE (i.e. machines with GPUs). If preemptible is true this can only be TERMINATE. If preemptible is false, it defaults to MIGRATE
preemptible (boolean) - If true, launch a preembtible instance.
region (string) - The region in which to launch the instance. Defaults to to the region hosting the specified zone.

scopes (array of strings) - The service account scopes for launched instance. Defaults to:

[
  "https://www.googleapis.com/auth/userinfo.email",
  "https://www.googleapis.com/auth/compute",
  "https://www.googleapis.com/auth/devstorage.full_control"
]

source_image_project_id (string) - The project ID of the project containing the source image.
startup_script_file (string) - The filepath to a startup script to run on the VM from which the image will be made.
state_timeout (string) - The time to wait for instance state changes. Defaults to "5m".
subnetwork (string) - The Google Compute subnetwork id or URL to use for the launched instance. Only required if the network has been created with custom subnetting. Note, the region of the subnetwork must match the region or zone in which the VM is launched.
tags (array of strings)
use_internal_ip (boolean) - If true, use the instance's internal IP instead of its external IP during building.

Startup Scripts

Startup scripts can be a powerful tool for configuring the instance from which the image is made. The builder will wait for a startup script to terminate. A startup script can be provided via the startup_script_file or 'startup-script' instance creation metadata field. Therefore, the build time will vary depending on the duration of the startup script. If startup_script_file is set, the 'startup-script' metadata field will be overwritten. In other words,startup_script_file takes precedence.

The builder does not check for a pass/fail/error signal from the startup script, at this time. Until such support is implemented, startup scripts should be robust, as an image will still be built even when a startup script fails.

Windows

A Windows startup script can only be provided via the 'windows-startup-script-cmd' instance creation metadata field. The builder will not wait for a Windows startup scripts to terminate. You have to ensure that it finishes before the instance shuts down.

Logging

Startup script logs can be copied to a Google Cloud Storage (GCS) location specified via the 'startup-script-log-dest' instance creation metadata field. The GCS location must be writeable by the credentials provided in the builder config's account_file.

Gotchas

CentOS and recent Debian images have root ssh access disabled by default. Set ssh_username to any user, which will be created by packer with sudo access.

The machine type must have a scratch disk, which means you can't use an f1-micro or g1-small to build images.

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