Using GitLab CI with GCP Workload Identity Federation.

3 min readMar 8, 2022
Using GitLab CI with GCP Workload Identity Federation

One of the challenges engineers face is the management, protection, distribution and renewal of Service Account keys.

The best way to reduce the security risks associated with this is not to use them.

While researching how to use Workload Identity Federation with GitLab CI, I came across this article from GitLab that explains how to configure OpenID Connect with GCP’s Workload Identity Federation. After the configuration, I realized that there are several ways to exploit the credential json file provided by Workload Identity Federation. In order to better understand this, we will perform two tests which are shown below.

Case 1: Use gsutil

For the test, we will follow the steps defined in this article 👇.

Regarding the Service Account linked to Workload Identity Federation, we will assign the following roles to it 👇.

Service Account related to Workload Identity Federation

Here is the result of March 08, 2022 👇👇👇

As you can see, we have a 401 error message indicating that we do not have storage.objects.list access to the Google Cloud Storage bucket. However, our Service Account has the Storage Object Admin role. Now let’s move on to the second test.

Here are the results for March 31, 2022 👇👇👇

On 2022–03–29, Google Cloud released version 379.0.0 of its CLI which resolved the previous permission issue.

On 2022–04–05, Google Cloud released version 380.0.0 which use bq for BigQuery.

Case 2: Python client library

Here we will use python code to exploit the json file provided by Workload Identity Federation.

Here is the result 👇👇👇

test result

As you can see, everything works fine with the same configurations we used in the first test.


What you need to understand here is that gsutil, bq, gcloud and terraform supports Workload Identity Federation as well as the python and Go client libraries. It work with Terraform which supports the environment variable GOOGLE_APPLICATION_CREDENTIALS .

For the record, I got the idea to write this article after a discussion with guillaume blaquiere who told me to avoid using Services Account for security reasons. He advised me to use Workload Identity Federation.




GDE & Champion Innovators for Google Cloud. Serverless & DevOps enthusiast. I like to learn from others, to share my knowledge with other people.