HashiCorp Packer & GCP with GitHub Actions

• building Google Cloud VM images using Packer and GitHub Actions
• authentication handled by Workload Identity Federation (WIF)

Medium: Getting started with HashiCorp Packer on Google Cloud Platform

Setup

0 - Fork this repo

1 - WIF Pool & GitHub Provider

Terraform code for setting up required GCP service accounts and WIF can be found here

2 - Update GitHub Workflow YAML

You will need to update the WIF_PROVIDER and WIF_SERVICE_ACCOUNT env vars in the packer.yaml accordingly for your GCP project and WIF Pool configuration

NOTE - You can get the WIF_PROVIDER with the following gcloud command (provider ID = github in my example):

gcloud iam workload-identity-pools providers describe ${WIF_PROVIDER_ID} \
    --location global \
    --workload-identity-pool ${WIF_POOL_ID} \
    --format='get(name)'

NOTE - I used GitHub's CLI tool, gh to set secrets via command line

3 - Push your commit!

Check the Actions tab and watch it go

NOTE - Using Credentials JSON

While not the recommended method of authenticating to Google Cloud, you can generate a credentials JSON key file and paste its contents into a GitHub repo secret:

jobs:
    [...]

    steps:
      [...]

      - name: 'Authenticate to Google Cloud'
        id: 'auth'
        uses: 'google-github-actions/auth@v1'
        with:
          credentials_json: '${{ secrets.GCP_CREDENTIALS_JSON }}'

      [...]

Run Locally

If you wish to run this locally without using GitHub Actions, you can do the following:

• authenticate using user application default creds

gcloud auth application-default login

PKR_VAR_access_token='xxxxxxxxxxxxx' packer build -var 'project_id=myproject-123' -var-file=variables.pkrvars.hcl base_docker.pkr.hcl`

NOTE: obtain access_token with gcloud auth print-access-token