# Packer example The following Packer example builds Compute Engine image based on Centos 8 Linux. The image is provisioned with a sample shell scripts to update OS packages and install HTTP server. The example uses following GCP features: * [service account impersonation](https://cloud.google.com/iam/docs/impersonating-service-accounts) * [Identity-Aware Proxy](https://cloud.google.com/iap/docs/using-tcp-forwarding) tunnel ## Variables | name | description | type | required | default | |---|---|:---: |:---:|:---:| | builder_sa | Image builder's service account email. | string | ✓ | | | compute_sa | Temporary's VM service account email. | string | ✓ | | | compute_subnetwork | Name of a VPC subnetwork for temporary VM instance. | string | ✓ | | | compute_zone | Compute Engine zone to run temporary VM instance. | string | ✓ | | | project_id | Project id that references existing GCP project. | string | ✓ | | | *use_iap* | Indicates to use IAP tunnel for communication with temporary VM instance. | bool | | true |