OpenID Connect (OIDC) Authentication Using ID Tokens

DETAILS: Tier: Free, Premium, Ultimate Offering: GitLab.com, Self-managed, GitLab Dedicated

Introduced in GitLab 15.7.

You can authenticate with third party services using GitLab CI/CD's ID tokens.

ID Tokens

ID tokens are JSON Web Tokens (JWTs) that can be added to a GitLab CI/CD job. They can be used for OIDC authentication with third-party services, and are used by the secrets keyword to authenticate with HashiCorp Vault.

ID tokens are configured in the .gitlab-ci.yml. For example:

job_with_id_tokens:
  id_tokens:
    FIRST_ID_TOKEN:
      aud: https://first.service.com
    SECOND_ID_TOKEN:
      aud: https://second.service.com
  script:
    - first-service-authentication-script.sh $FIRST_ID_TOKEN
    - second-service-authentication-script.sh $SECOND_ID_TOKEN

In this example, the two tokens have different aud claims. Third party services can be configured to reject tokens that do not have an aud claim matching their bound audience. Use this functionality to reduce the number of services with which a token can authenticate. This reduces the severity of having a token compromised.

Token payload

The following standard claims are included in each ID token:

Field	Description
`iss`	Issuer of the token, which is the domain of the GitLab instance ("issuer" claim).
`sub`	`project_path:{group}/{project}:ref_type:{type}:ref:{branch_name}` ("subject" claim).
`aud`	Intended audience for the token ("audience" claim). Specified in the ID tokens configuration. The domain of the GitLab instance by default.
`exp`	The expiration time ("expiration time" claim).
`nbf`	The time after which the token becomes valid ("not before" claim).
`iat`	The time the JWT was issued ("issued at" claim).
`jti`	Unique identifier for the token ("JWT ID" claim).

The token also includes custom claims provided by GitLab:

Field	When	Description
`namespace_id`	Always	Use this to scope to group or user level namespace by ID.
`namespace_path`	Always	Use this to scope to group or user level namespace by path.
`project_id`	Always	Use this to scope to project by ID.
`project_path`	Always	Use this to scope to project by path.
`user_id`	Always	ID of the user executing the job.
`user_login`	Always	Username of the user executing the job.
`user_email`	Always	Email of the user executing the job.
`user_access_level`	Always	Access level of the user executing the job. Introduced in GitLab 16.9.
`user_identities`	User Preference setting	List of the user's external identities (introduced in GitLab 16.0).
`pipeline_id`	Always	ID of the pipeline.
`pipeline_source`	Always	Pipeline source.
`job_id`	Always	ID of the job.
`ref`	Always	Git ref for the job.
`ref_type`	Always	Git ref type, either `branch` or `tag`.
`ref_path`	Always	Fully qualified ref for the job. For example, `refs/heads/main`. Introduced in GitLab 16.0.
`ref_protected`	Always	`true` if the Git ref is protected, `false` otherwise.
`groups_direct`	User is a direct member of 0 to 200 groups	The paths of the user's direct membership groups. Omitted if the user is a direct member of more than 200 groups. (Introduced in GitLab 16.11 and put behind the `ci_jwt_groups_direct` feature flag in GitLab 17.3.
`environment`	Job specifies an environment	Environment this job deploys to.
`environment_protected`	Job specifies an environment	`true` if deployed environment is protected, `false` otherwise.
`deployment_tier`	Job specifies an environment	Deployment tier of the environment the job specifies. Introduced in GitLab 15.2.
`environment_action`	Job specifies an environment	Environment action (`environment:action`) specified in the job. (Introduced in GitLab 16.5)
`runner_id`	Always	ID of the runner executing the job. Introduced in GitLab 16.0.
`runner_environment`	Always	The type of runner used by the job. Can be either `gitlab-hosted` or `self-hosted`. Introduced in GitLab 16.0.
`sha`	Always	The commit SHA for the job. Introduced in GitLab 16.0.
`ci_config_ref_uri`	Always	The ref path to the top-level pipeline definition, for example, `gitlab.example.com/my-group/my-project//.gitlab-ci.yml@refs/heads/main`. Introduced in GitLab 16.2. This claim is `null` unless the pipeline definition is located in the same project.
`ci_config_sha`	Always	Git commit SHA for the `ci_config_ref_uri`. Introduced in GitLab 16.2. This claim is `null` unless the pipeline definition is located in the same project.
`project_visibility`	Always	The visibility of the project where the pipeline is running. Can be `internal`, `private`, or `public`. Introduced in GitLab 16.3.

{
  "namespace_id": "72",
  "namespace_path": "my-group",
  "project_id": "20",
  "project_path": "my-group/my-project",
  "user_id": "1",
  "user_login": "sample-user",
  "user_email": "sample-user@example.com",
  "user_identities": [
      {"provider": "github", "extern_uid": "2435223452345"},
      {"provider": "bitbucket", "extern_uid": "john.smith"},
  ],
  "pipeline_id": "574",
  "pipeline_source": "push",
  "job_id": "302",
  "ref": "feature-branch-1",
  "ref_type": "branch",
  "ref_path": "refs/heads/feature-branch-1",
  "ref_protected": "false",
  "groups_direct": ["mygroup/mysubgroup", "myothergroup/myothersubgroup"],
  "environment": "test-environment2",
  "environment_protected": "false",
  "deployment_tier": "testing",
  "environment_action": "start",
  "runner_id": 1,
  "runner_environment": "self-hosted",
  "sha": "714a629c0b401fdce83e847fc9589983fc6f46bc",
  "project_visibility": "public",
  "ci_config_ref_uri": "gitlab.example.com/my-group/my-project//.gitlab-ci.yml@refs/heads/main",
  "ci_config_sha": "714a629c0b401fdce83e847fc9589983fc6f46bc",
  "jti": "235b3a54-b797-45c7-ae9a-f72d7bc6ef5b",
  "iss": "https://gitlab.example.com",
  "iat": 1681395193,
  "nbf": 1681395188,
  "exp": 1681398793,
  "sub": "project_path:my-group/my-project:ref_type:branch:ref:feature-branch-1",
  "aud": "https://vault.example.com"
}

The ID token is encoded by using RS256 and signed with a dedicated private key. The expiry time for the token is set to the job's timeout if specified, or 5 minutes if no timeout is specified.

Manual ID Token authentication

You can use ID tokens for OIDC authentication with a third party service. For example:

manual_authentication:
  variables:
    VAULT_ADDR: http://vault.example.com:8200
  image: vault:latest
  id_tokens:
    VAULT_ID_TOKEN:
      aud: http://vault.example.com
  script:
    - export VAULT_TOKEN="$(vault write -field=token auth/jwt/login role=myproject-example jwt=$VAULT_ID_TOKEN)"
    - export PASSWORD="$(vault kv get -field=password secret/myproject/example/db)"
    - my-authentication-script.sh $VAULT_TOKEN $PASSWORD

Automatic ID Token authentication with HashiCorp Vault

DETAILS: Tier: Premium, Ultimate Offering: GitLab.com, Self-managed, GitLab Dedicated

You can use ID tokens to automatically fetch secrets from HashiCorp Vault with the secrets keyword.

If you previously used CI_JOB_JWT to fetch secrets from Vault, learn how to switch to ID tokens with the Update HashiCorp Vault configuration to use ID Tokens tutorial.

Configure automatic ID Token authentication

If one ID token is defined, the secrets keyword automatically uses it to authenticate with Vault. For example:

job_with_secrets:
  id_tokens:
    VAULT_ID_TOKEN:
      aud: https://vault.example.com
  secrets:
    PROD_DB_PASSWORD:
      vault: example/db/password # authenticates using $VAULT_ID_TOKEN
  script:
    - access-prod-db.sh --token $PROD_DB_PASSWORD

If more than one ID token is defined, use the token keyword to specify which token should be used. For example:

job_with_secrets:
  id_tokens:
    FIRST_ID_TOKEN:
      aud: https://first.service.com
    SECOND_ID_TOKEN:
      aud: https://second.service.com
  secrets:
    FIRST_DB_PASSWORD:
      vault: first/db/password
      token: $FIRST_ID_TOKEN
    SECOND_DB_PASSWORD:
      vault: second/db/password
      token: $SECOND_ID_TOKEN
  script:
    - access-first-db.sh --token $FIRST_DB_PASSWORD
    - access-second-db.sh --token $SECOND_DB_PASSWORD

Troubleshooting

`400: missing token` status code

This error indicates that one or more basic components necessary for ID tokens are either missing or not configured as expect.

To find the problem, an administrator can look for more details in the instance's exceptions_json.log for the specific method that failed.

`GitLab::Ci::Jwt::NoSigningKeyError`

This error in the exceptions_json.log file is likely because the signing key is missing from the database and the token could not be generated. To verify this is the issue, run the following query on the instance's PostgreSQL terminal:

SELECT encrypted_ci_jwt_signing_key FROM application_settings;

If the returned value is empty, use the Rails snippet below to generate a new key and replace it internally:

  key = OpenSSL::PKey::RSA.new(2048).to_pem

  ApplicationSetting.find_each do |application_setting|
    application_setting.update(ci_jwt_signing_key: key)
  end