---
description: |
    The `googlecompute` Packer builder is able to create images for use with Google
    Compute Engine (GCE) based on existing images. Google Compute Engine doesn't
    allow the creation of images from scratch.
layout: docs
page_title: Google Compute Builder
...

# Google Compute Builder

Type: `googlecompute`

The `googlecompute` Packer builder is able to create
[images](https://developers.google.com/compute/docs/images) for use with [Google
Compute Engine](https://cloud.google.com/products/compute-engine)(GCE) based on
existing images. Google Compute Engine doesn't allow the creation of 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](https://cloud.google.com/compute/docs/authentication).

### 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](https://cloud.google.com/compute/docs/authentication). 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:

``` {.sh}
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](https://console.developers.google.com):

1.  Choose "Show advanced options"
2.  Tick "Enable Compute Engine service account"
3.  Choose "Read Write" for Compute
4.  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](https://console.developers.google.com) 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.

1.  Log into the [Google Developers
    Console](https://console.developers.google.com) and select a project.

2.  Under the "APIs & Auth" section, click "Credentials."

3.  Click the "Create new Client ID" button, select "Service account", and click
    "Create Client ID"

4.  Click "Generate new JSON key" for the Service Account you just created. A
    JSON file will be downloaded automatically. This is your *account file*.

## Basic Example

Below is a fully functioning example. It doesn't do anything useful, since no
provisioners 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.

``` {.javascript}
{
  "type": "googlecompute",
  "account_file": "account.json",
  "project_id": "my-project",
  "source_image": "debian-7-wheezy-v20150127",
  "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](/docs/templates/communicator.html) 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. Example: `"debian-7-wheezy-v20150127"`

-   `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.

-   `disk_size` (integer) - The size of the disk in GB. This defaults to `10`,
    which is 10GB.

-   `image_name` (string) - The unique name of the resulting image. Defaults to
    `"packer-{{timestamp}}"`.

-   `image_description` (string) - The description of the resulting image.

-   `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)

-   `network` (string) - The Google Compute network to use for the
    launched instance. Defaults to `"default"`.

-   `state_timeout` (string) - The time to wait for instance state changes.
    Defaults to `"5m"`.

-   `tags` (array of strings)

-   `use_internal_ip` (boolean) - If true, use the instance's internal IP
    instead of its external IP during building.

## Gotchas

Centos 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.