Configure OpenID Connect with GCP Workload Identity Federation All tiers All offerings
CI_JOB_JWT_V2
was deprecated in GitLab 15.9
and is scheduled to be removed in GitLab 17.0. Use ID tokens instead.This tutorial demonstrates authenticating to Google Cloud from a GitLab CI/CD job using a JSON Web Token (JWT) token and Workload Identity Federation. This configuration generates on-demand, short-lived credentials without needing to store any secrets.
To get started, configure OpenID Connect (OIDC) for identity federation between GitLab and Google Cloud. For more information on using OIDC with GitLab, read Connect to cloud services.
This tutorial assumes you have a Google Cloud account and a Google Cloud project. Your account must have at least the Workload Identity Pool Admin permission on the Google Cloud project.
To complete this tutorial:
- Create the Google Cloud Workload Identity Pool.
- Create a Workload Identity Provider.
- Grant permissions for service account impersonation.
- Retrieve a temporary credential.
Create the Google Cloud Workload Identity Pool
Create a new Google Cloud Workload Identity Pool with the following options:
-
Name: Human-friendly name for the Workload Identity Pool, such as
GitLab
. -
Pool ID: Unique ID in the Google Cloud project for the Workload Identity Pool,
such as
gitlab
. This value is used to refer to the pool. and appears in URLs. - Description: Optional. A description of the pool.
-
Enabled Pool: Ensure this option is
true
.
We recommend creating a single pool per GitLab installation per Google Cloud project. If you have multiple GitLab repositories and CI/CD jobs on the same GitLab instance, they can authenticate using different providers against the same pool.
Create a Workload Identity Provider
Create a new Google Cloud Workload Identity Provider inside the Workload Identity Pool created in the previous step, using the following options:
- Provider type: OpenID Connect (OIDC).
-
Provider name: Human-friendly name for the Workload Identity Provider,
such as
gitlab/gitlab
. -
Provider ID: Unique ID in the pool for the Workload Identity Provider,
such as
gitlab-gitlab
. This value is used to refer to the provider, and appears in URLs. -
Issuer (URL): The address of your GitLab instance, such as
https://gitlab.com/
orhttps://gitlab.example.com/
.- The address must use the
https://
protocol. - The address must end in a trailing slash.
- The address must use the
-
Audiences: Manually set the allowed audiences list to the address of your
GitLab instance, such as
https://gitlab.com
orhttps://gitlab.example.com
.- The address must use the
https://
protocol. - The address must not end in a trailing slash.
- The address must use the
-
Provider attributes mapping: Create the following mappings, where
attribute.X
is the name of the attribute you would like to be present on Google’s claims, andassertion.X
is the value to extract from the GitLab claim:Attribute (on Google) Assertion (from GitLab) google.subject
assertion.sub
attribute.X
assertion.X
You can also build complex attributes using Common Expression Language (CEL).
You must map every attribute that you want to use for permission granting. For example, if you want to map permissions in the next step based on the user’s email address, you must map
attribute.user_email
toassertion.user_email
.
Grant permissions for Service Account impersonation
Creating the Workload Identity Pool and Workload Identity Provider defines the authentication into Google Cloud. At this point, you can authenticate from GitLab CI/CD job into Google Cloud. However, you have no permissions on Google Cloud (authorization).
To grant your GitLab CI/CD job permissions on Google Cloud, you must:
- Create a Google Cloud Service Account. You can use whatever name and ID you prefer.
-
Grant IAM permissions to your
service account on Google Cloud resources. These permissions vary significantly based on
your use case. In general, grant this service account the permissions on your Google Cloud
project and resources you want your GitLab CI/CD job to be able to use. For example, if you needed to upload a file to a Google Cloud Storage bucket in your GitLab CI/CD job, you would grant this Service Account the
roles/storage.objectCreator
role on your Cloud Storage bucket. -
Grant the external identity permissions
to impersonate that Service Account. This step enables a GitLab CI/CD job to authorize
to Google Cloud, via Service Account impersonation. This step grants an IAM permission
on the Service Account itself, giving the external identity permissions to act as that
service account. External identities are expressed using the
principalSet://
protocol.
Much like the previous step, this step depends heavily on your desired configuration.
For example, to allow a GitLab CI/CD job to impersonate a Service Account named
my-service-account
if the GitLab CI/CD job was initiated by a GitLab user with the
username chris
, you would grant the roles/iam.workloadIdentityUser
IAM role to the
external identity on my-service-account
. The external identity takes the format:
principalSet://iam.googleapis.com/projects/PROJECT_NUMBER/locations/global/workloadIdentityPools/POOL_ID/attribute.user_login/chris
where PROJECT_NUMBER
is your Google Cloud project number, and POOL_ID
is the
ID (not name) of the Workload Identity Pool created in the first section.
This configuration also assumes you added user_login
as an attribute mapped from
the assertion in the previous section.
Retrieve a temporary credential
After you configure the OIDC and role, the GitLab CI/CD job can retrieve a temporary credential from the Google Cloud Security Token Service (STS).
Add id_tokens
to your CI/CD job:
job:
id_tokens:
GITLAB_OIDC_TOKEN:
aud: https://gitlab.example.com
Get temporary credentials using the ID token:
PAYLOAD="$(cat <<EOF
{
"audience": "//iam.googleapis.com/projects/PROJECT_NUMBER/locations/global/workloadIdentityPools/POOL_ID/providers/PROVIDER_ID",
"grantType": "urn:ietf:params:oauth:grant-type:token-exchange",
"requestedTokenType": "urn:ietf:params:oauth:token-type:access_token",
"scope": "https://www.googleapis.com/auth/cloud-platform",
"subjectTokenType": "urn:ietf:params:oauth:token-type:jwt",
"subjectToken": "${GITLAB_OIDC_TOKEN}"
}
EOF
)"
FEDERATED_TOKEN="$(curl --fail "https://sts.googleapis.com/v1/token" \
--header "Accept: application/json" \
--header "Content-Type: application/json" \
--data "${PAYLOAD}" \
| jq -r '.access_token'
)"
Where:
-
PROJECT_NUMBER
is your Google Cloud project number (not name). -
POOL_ID
is the ID of the Workload Identity Pool created in the first section. -
PROVIDER_ID
is the ID of the Workload Identity Provider created in the second section. -
GITLAB_OIDC_TOKEN
is an OIDC ID token.
You can then use the resulting federated token to impersonate the service account created in the previous section:
ACCESS_TOKEN="$(curl --fail "https://iamcredentials.googleapis.com/v1/projects/-/serviceAccounts/SERVICE_ACCOUNT_EMAIL:generateAccessToken" \
--header "Accept: application/json" \
--header "Content-Type: application/json" \
--header "Authorization: Bearer FEDERATED_TOKEN" \
--data '{"scope": ["https://www.googleapis.com/auth/cloud-platform"]}' \
| jq -r '.accessToken'
)"
Where:
-
SERVICE_ACCOUNT_EMAIL
is the full email address of the service account to impersonate, created in the previous section. -
FEDERATED_TOKEN
is the federated token retrieved from the previous step.
The result is a Google Cloud OAuth 2.0 access token, which you can use to authenticate to
most Google Cloud APIs and services when used as a bearer token. You can also pass this
value to the gcloud
CLI by setting the environment variable CLOUDSDK_AUTH_ACCESS_TOKEN
.
Working example
Review this reference project for provisioning OIDC in GCP using Terraform and a sample script to retrieve temporary credentials.
Troubleshooting
-
When debugging
curl
responses, install the latest version of curl. Use--fail-with-body
instead of-f
. This command prints the entire body, which can contain helpful error messages. -
Review Google Cloud’s documentation for Troubleshooting Workload Identity Federation.