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Kapp deploy on GKE using keyless authentication (OIDC)

by Yash Sethiya — Jul 21, 2022

Who

This article can be helpful for anyone who wants to create the Github Action workflow to authenticate with GCP and to deploy Kubernetes manifest on GKE using kapp.

Why

Earlier, we used to authenticate to Google Cloud from GitHub Actions by storing JSON service account key in GitHub Secrets.

Now, that GitHub introduced OIDC tokens into GitHub Actions Workflows, you can authenticate from GitHub Actions to Google Cloud using OIDC (Workload Identity Federation), removing the need to export a long lived JSON service account key. Please refer here to know more about the benefits of using OIDC.

How

Now we will see how we can use GitHub Action – auth to set up and configure authentication to Google Cloud. We need to perform the following configurations on GCP -

  1. Create a new Workload Identity Pool (IAM -> Workload Identity Federation -> Workload Identity Pool) and add an OIDC Provider to it with Issuer URL as https://token.actions.githubusercontent.com.
  2. Configure the Attribute mapping and conditions of the provider.
  3. Create a service account and connect Workload Identity Pool you just created to the service account by assigning Workload Identity User role. For more information, see the GCP documentation.

To update workflows for OIDC, you will need to make two changes to your GitHub Action YAML:

  1. Add permissions settings for the token. The job or workflow run requires a permissions setting with id-token: write. You won’t be able to request the OIDC JWT ID token if the permissions setting for id-token is set to read or none.
permissions:
  id-token: write
  1. Use the google-github-actions/auth action to exchange the OIDC token (JWT) for a cloud access token.
steps:
- id: 'auth'
  name: 'Authenticate to Google Cloud'
  uses: 'google-github-actions/auth@v0.4.0'
  with:
    workload_identity_provider: 'projects/123456789/locations/global/workloadIdentityPools/my-pool/providers/my-provider'
    service_account: 'my-service-account@my-project.iam.gserviceaccount.com'

This will use the configured workload_identity_provider and service_account to authenticate future steps. Make sure to replace the value of workload_identity_provider with the path to your identity provider in GCP and also replace the value of service_account key with the name of your service account in GCP.

Example

Here is a sample GitHub Action which gets triggered when a new tag is created on the repo. It authenticates with GCP, gets the GKE credentials, installs Carvel tools on the GKE cluster, and deploys a simple app using kapp.

name: Deploy using kapp

on:
  push:
    tags:
      - "v*"

jobs:
  deploy:
    runs-on: ubuntu-latest

    permissions:
      id-token: 'write'

    steps:
      # actions/checkout MUST come before auth
      - uses: 'actions/checkout@v3'

      - id: 'auth'
        name: 'Authenticate to Google Cloud'
        uses: 'google-github-actions/auth@v0.4.0'
        with:
          workload_identity_provider: 'projects/123456789/locations/global/workloadIdentityPools/my-pool/providers/my-provider'
          service_account: 'my-service-account@my-project.iam.gserviceaccount.com'

      - id: get-gke-credentials
        uses: google-github-actions/get-gke-credentials@v0.4.0
        with:
          cluster_name: cluster-yash
          location: us-central1-a

      - id: install-kapp
        uses: vmware-tanzu/carvel-setup-action@v1
        with:
          only: kapp
         
      - id: 'deploy-with-kapp'
        run: |-
          kapp deploy -a app -f simple-app.yml -y
          kapp ls          

We created this sample GitHub repo for reference to help guide you, which contains a GitHub Action and simple-app.yml which we deploy on GKE using kapp as mentioned above. Thanks for following along! We hope you found this helpful.

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