• GCP service account with appropriate roles
• VPC network subnet specification for instance creation
• Packer

• Authenticating with Google Cloud services requires a JSON Service Account Key.
• To create a custom service account for Packer and assign to it Compute Instance Admin (v1) & Service Account User roles, follow the below instructions:
  • Log in to 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.

• gce_credentials: (mandatory) - The JSON file containing GCP account credentials. Environment variable name - GCE_CREDENTIALS.

• gce_project_id: (mandatory) - The ID of the GCP project that will be used to launch instances and store images. Environment variable name - GCE_PROJECT_ID.

• gce_zone: (mandatory) - The zone to launch the instance used to create the image. Example: "us-central1-a". Environment variable name - GCE_ZONE.

• gce_subnet_id (mandatory) - 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: If the value is not a URL, it will be interpolated to projects/((network_project_id))/regions/((region))/subnetworks/((subnetwork))

  Environment variable name - GCE_SUBNET_ID.

• gce_source_image_family: (optional) - The source image family to use as a base image for the golden image. Example: "debian-10"

• ssh_username: (optional) - The username to SSH the instance. Required if using SSH.

• custom_image_name: (optional) - The unique name of the resulting image. Defaults to packer-{{timestamp}}

• custom_image_family: (optional) - The name of the image family to which the resulting image belongs.

NOTE:

• All the mandatory parameters in the above list should be passed either with the environment variable or in the command line with the packer build command. Check - How to Set Environment Variable.
• If the environment variable is provided and the parameter is passed using the command line, the value provided in the command line is preferred.
• The name of the environment variable is provided in the above list.
• All the optional parameters in the above list could be passed in the command line with the packer build command.

• Windows:
  • Open command prompt.
  • Set the Environment Variable:

     set GCE_CREDENTIALS=/file/path/to/credentials.json
    

  • Verifying the set Environment Variable:

     echo %GCE_CREDENTIALS%
    

• Linux/Unix or Mac:
  • Open Terminal.
  • Set the Environment Variable:

     export GCE_CREDENTIALS=/file/path/to/credentials.json
    

  • Verifying the set Environment Variable:

     echo $GCE_CREDENTIALS
    

• If all the mandatory parameters are passed using the environment variable and it's not required to pass the optional parameters, run the packer script:

     packer build image.json
  

• If it's required that the mandatory parameters or any of the optional parameters should be passed in the command line with the packer build command, run the packer script in the following way:

      packer build -var 'gce_credentials=/file/path/to/credentials.json' -var 'gce_project_id=project_id_1234' -var 'gce_zone=us-central1-a' -var 'custom_image_name=image_name' image.json
  

• If default VPC does not exists and you want to specify your own subnetted vpc network then in environment variable GCE_SUBNET_ID set the value of your subnet URL or subnet ID.
• For example:
  • For subnet URL, set environment variable GCE_SUBNET_ID value to "https://www.googleapis.com/compute/v1/projects/YOUR_PROJECT_ID/regions/REGION/subnetworks/SUBNETWORK".
  • For subnet ID, set environment variable GCE_SUBNET_ID value to "SUBNETWORK".

Note: The region of the subnetwork must match the region or zone in which the VM is launched.

• If the default vpc exists then in environment variable GCE_SUBNET_ID set the value "default".

• If you get error like: command not found then run below commands to install and update required packages.

   sudo apt-get install software-properties-common git -y
   sudo apt-get update -y