Use OpenID Connect as an authentication provider

DETAILS: Tier: Free, Premium, Ultimate Offering: Self-managed

You can use GitLab as a client application with OpenID Connect as an OmniAuth provider.

To enable the OpenID Connect OmniAuth provider, you must register your application with an OpenID Connect provider. The OpenID Connect provider provides you with a client's details and secret for you to use.

On your GitLab server, open the configuration file.

For Linux package installations:
```
sudo editor /etc/gitlab/gitlab.rb
```
For self-compiled installations:
```
cd /home/git/gitlab
sudo -u git -H editor config/gitlab.yml
```
Configure the common settings to add openid_connect as a single sign-on provider. This enables Just-In-Time account provisioning for users who do not have an existing GitLab account.

Add the provider configuration.

For Linux package installations:

gitlab_rails['omniauth_providers'] = [
  {
    name: "openid_connect", # do not change this parameter
    label: "Provider name", # optional label for login button, defaults to "Openid Connect"
    icon: "<custom_provider_icon>",
    args: {
      name: "openid_connect",
      scope: ["openid","profile","email"],
      response_type: "code",
      issuer: "<your_oidc_url>",
      discovery: true,
      client_auth_method: "query",
      uid_field: "<uid_field>",
      send_scope_to_token_endpoint: "false",
      pkce: true,
      client_options: {
        identifier: "<your_oidc_client_id>",
        secret: "<your_oidc_client_secret>",
        redirect_uri: "<your_gitlab_url>/users/auth/openid_connect/callback"
      }
    }
  }
]

For Linux package installations with multiple identity providers:

{ 'name' => 'openid_connect',
  'label' => '...',
  'icon' => '...',
  'args' => {
    'name' => 'openid_connect',
    'strategy_class': 'OmniAuth::Strategies::OpenIDConnect',
    'scope' => ['openid', 'profile', 'email'],
    'discovery' => true,
    'response_type' => 'code',
    'issuer' => 'https://...',
    'client_auth_method' => 'query',
    'uid_field' => '...',
    'client_options' => {
      `identifier`: "<your_oidc_client_id>",
      `secret`: "<your_oidc_client_secret>",
      'redirect_uri' => 'https://.../users/auth/openid_connect/callback'
   }
 }
},
{ 'name' => 'openid_connect_2fa',
  'label' => '...',
  'icon' => '...',
  'args' => {
    'name' => 'openid_connect_2fa',
    'strategy_class': 'OmniAuth::Strategies::OpenIDConnect',
    'scope' => ['openid', 'profile', 'email'],
    'discovery' => true,
    'response_type' => 'code',
    'issuer' => 'https://...',
    'client_auth_method' => 'query',
    'uid_field' => '...',
    'client_options' => {
     ...
     'redirect_uri' => 'https://.../users/auth/openid_connect_2fa/callback'
   }
 }
}

NOTE: For more information on using multiple identity providers with OIDC, see issue 5992.

For self-compiled installations:

  - { name: 'openid_connect', # do not change this parameter
      label: 'Provider name', # optional label for login button, defaults to "Openid Connect"
      icon: '<custom_provider_icon>',
      args: {
        name: 'openid_connect',
        scope: ['openid','profile','email'],
        response_type: 'code',
        issuer: '<your_oidc_url>',
        discovery: true,
        client_auth_method: 'query',
        uid_field: '<uid_field>',
        send_scope_to_token_endpoint: false,
        pkce: true,
        client_options: {
          identifier: '<your_oidc_client_id>',
          secret: '<your_oidc_client_secret>',
          redirect_uri: '<your_gitlab_url>/users/auth/openid_connect/callback'
        }
      }
    }

NOTE: For more information on each configuration option, refer to the OmniAuth OpenID Connect usage documentation and OpenID Connect Core 1.0 specification.

For the provider configuration, change the values for the provider to match your OpenID Connect client setup. Use the following as a guide:
- <your_oidc_label> is the label that appears on the login page.
- <custom_provider_icon> (optional) is the icon that appears on the login page. Icons for the major social login platforms are built into GitLab, but you can override these icons by specifying this parameter. GitLab accepts both local paths and absolute URLs.
- <your_oidc_url> (optional) is the URL that points to the OpenID Connect provider (for example, https://example.com/auth/realms/your-realm). If this value is not provided, the URL is constructed from client_options in the following format: <client_options.scheme>://<client_options.host>:<client_options.port>.
- If discovery is set to true, the OpenID Connect provider attempts to automatically discover the client options using <your_oidc_url>/.well-known/openid-configuration. Defaults to false.
- client_auth_method (optional) specifies the method used for authenticating the client with the OpenID Connect provider.
  - Supported values are:
    - basic - HTTP Basic Authentication.
    - jwt_bearer - JWT-based authentication (private key and client secret signing).
    - mtls - Mutual TLS or X.509 certificate validation.
    - Any other value posts the client ID and secret in the request body.
  - If not specified, this value defaults to basic.
- <uid_field> (optional) is the field name from user_info.raw_attributes that defines the value for uid (for example, preferred_username). If you do not provide this value, or the field with the configured value is missing from the user_info.raw_attributes details, uid uses the sub field.
- send_scope_to_token_endpoint is true by default, so the scope parameter is usually included in requests to the token endpoint. However, if your OpenID Connect provider does not accept the scope parameter in such requests, set this to false.
- pkce (optional): Enable Proof Key for Code Exchange. Available in GitLab 15.9.
- client_options are the OpenID Connect client-specific options. Specifically:
  - identifier is the client identifier as configured in the OpenID Connect service provider.
  - secret is the client secret as configured in the OpenID Connect service provider. For example, OmniAuth OpenID Connect requires this. If the service provider doesn't require a secret, provide any value and it is ignored.
  - redirect_uri is the GitLab URL to redirect the user to after successful login (for example, http://example.com/users/auth/openid_connect/callback).
  - end_session_endpoint (optional) is the URL to the endpoint that ends the session. You can provide this URL if auto-discovery is disabled or unsuccessful.
  - The following client_options are optional unless auto-discovery is disabled or unsuccessful:
    - authorization_endpoint is the URL to the endpoint that authorizes the end user.
    - token_endpoint is the URL to the endpoint that provides Access Token.
    - userinfo_endpoint is the URL to the endpoint that provides the user information.
    - jwks_uri is the URL to the endpoint where the Token signer publishes its keys.
Save the configuration file.
For changes to take effect, if you:
- Used the Linux package to install GitLab, reconfigure GitLab.
- Self-compiled your GitLab installation, restart GitLab.

On the sign in page, you have an OpenID Connect option below the regular sign in form. Select this option to begin the authentication process. The OpenID Connect provider asks you to sign in and authorize the GitLab application if confirmation is required by the client. You are redirected to GitLab and signed in.

Example configurations

The following configurations illustrate how to set up OpenID with different providers when using the Linux package installation.

Configure Google

See the Google documentation for more details:

gitlab_rails['omniauth_providers'] = [
  {
    name: "openid_connect", # do not change this parameter
    label: "Google OpenID", # optional label for login button, defaults to "Openid Connect"
    args: {
      name: "openid_connect",
      scope: ["openid", "profile", "email"],
      response_type: "code",
      issuer: "https://accounts.google.com",
      client_auth_method: "query",
      discovery: true,
      uid_field: "preferred_username",
      pkce: true,
      client_options: {
        identifier: "<YOUR PROJECT CLIENT ID>",
        secret: "<YOUR PROJECT CLIENT SECRET>",
        redirect_uri: "https://example.com/users/auth/openid_connect/callback",
       }
     }
  }
]

Configure Microsoft Azure

The OpenID Connect (OIDC) protocol for Microsoft Azure uses the Microsoft identity platform (v2) endpoints. To get started, sign in to the Azure Portal. For your app, you need the following information:

A tenant ID. You may already have one. For more information, see the Microsoft Azure Tenant documentation.
A client ID and a client secret. Follow the instructions in the Microsoft Quickstart Register an Application documentation to obtain the tenant ID, client ID, and client secret for your app.

Example configuration block for Linux package installations:

gitlab_rails['omniauth_providers'] = [
  {
    name: "openid_connect", # do not change this parameter
    label: "Azure OIDC", # optional label for login button, defaults to "Openid Connect"
    args: {
      name: "openid_connect",
      scope: ["openid", "profile", "email"],
      response_type: "code",
      issuer:  "https://login.microsoftonline.com/<YOUR-TENANT-ID>/v2.0",
      client_auth_method: "query",
      discovery: true,
      uid_field: "preferred_username",
      pkce: true,
      client_options: {
        identifier: "<YOUR APP CLIENT ID>",
        secret: "<YOUR APP CLIENT SECRET>",
        redirect_uri: "https://gitlab.example.com/users/auth/openid_connect/callback"
      }
    }
  }
]

Microsoft has documented how its platform works with the OIDC protocol.

Microsoft Entra custom signing keys

If your application has custom signing keys because you use the SAML claims-mapping feature, you must configure the OpenID provider in the following ways:

Disable OpenID Connect Discovery by omitting args.discovery, or setting it to false.
In client_options, specify the following:
- A jwks_uri with the appid query parameter: https://login.microsoftonline.com/<YOUR-TENANT-ID>/discovery/v2.0/keys?appid=<YOUR APP CLIENT ID>.
- end_session_endpoint.
- authorization_endpoint.
- userinfo_endpoint.

Example configuration for Linux package installations:

gitlab_rails['omniauth_providers'] = [
 {
    name: "openid_connect", # do not change this parameter
    label: "Azure OIDC", # optional label for login button, defaults to "Openid Connect"
    args: {
      name: "openid_connect",
      scope: ["openid", "profile", "email"],
      response_type: "code",
      issuer:  "https://login.microsoftonline.com/<YOUR-TENANT-ID>/v2.0",
      client_auth_method: "basic",
      discovery: false,
      uid_field: "preferred_username",
      pkce: true,
      client_options: {
        identifier: "<YOUR APP CLIENT ID>",
        secret: "<YOUR APP CLIENT SECRET>",
        redirect_uri: "https://gitlab.example.com/users/auth/openid_connect/callback",
        end_session_endpoint: "https://login.microsoftonline.com/<YOUR-TENANT-ID>/oauth2/v2.0/logout",
        authorization_endpoint: "https://login.microsoftonline.com/<YOUR-TENANT-ID>/oauth2/v2.0/authorize",
        token_endpoint: "https://login.microsoftonline.com/<YOUR-TENANT-ID>/oauth2/v2.0/token",
        userinfo_endpoint: "https://graph.microsoft.com/oidc/userinfo",
        jwks_uri: "https://login.microsoftonline.com/<YOUR-TENANT-ID>/discovery/v2.0/keys?appid=<YOUR APP CLIENT ID>"
      }
    }
  }
]

If you see authentication failures with a KidNotFound message, this is probably because of a missing or incorrect appid query parameter. GitLab raises that error if the ID token returned by Microsoft cannot be validated with the keys provided by the jwks_uri endpoint.

For more information, see the Microsoft Entra documentation on validating tokens.

Migrate to Generic OpenID Connect configuration

You can migrate to the Generic OpenID Connect configuration from both azure_activedirectory_v2 and azure_oauth2.

First, set the uid_field. Both the uid_field and the sub claim that you can select as a uid_field vary depending on the provider. Signing in without setting the uid_field results in additional identities being created within GitLab that have to be manually modified:

Provider	`uid_field`	Supporting information
`omniauth-azure-oauth2`	`sub`	Additional attributes `oid` and `tid` are offered within the `info` object.
`omniauth-azure-activedirectory-v2`	`oid`	You must configure `oid` as `uid_field` when migrating.
`omniauth_openid_connect`	`sub`	Specify `uid_field` to use another field.

To migrate to the Generic OpenID Connect configuration, you must update the configuration.

For Linux package installations, update the configuration as follows:

::Tabs

:::TabTitle Azure OAuth 2.0

gitlab_rails['omniauth_providers'] = [
  {
    name: "azure_oauth2",
    label: "Azure OIDC", # optional label for login button, defaults to "Openid Connect"
    args: {
      name: "azure_oauth2", # this matches the existing azure_oauth2 provider name, and only the strategy_class immediately below configures OpenID Connect
      strategy_class: "OmniAuth::Strategies::OpenIDConnect",
      scope: ["openid", "profile", "email"],
      response_type: "code",
      issuer:  "https://login.microsoftonline.com/<YOUR-TENANT-ID>/v2.0",
      client_auth_method: "query",
      discovery: true,
      uid_field: "sub",
      send_scope_to_token_endpoint: "false",
      client_options: {
        identifier: "<YOUR APP CLIENT ID>",
        secret: "<YOUR APP CLIENT SECRET>",
        redirect_uri: "https://gitlab.example.com/users/auth/azure_oauth2/callback"
      }
    }
  }
]

:::TabTitle Azure Active Directory v2

gitlab_rails['omniauth_providers'] = [
  {
    name: "azure_activedirectory_v2",
    label: "Azure OIDC", # optional label for login button, defaults to "Openid Connect"
    args: {
      name: "azure_activedirectory_v2",
      strategy_class: "OmniAuth::Strategies::OpenIDConnect",
      scope: ["openid", "profile", "email"],
      response_type: "code",
      issuer:  "https://login.microsoftonline.com/<YOUR-TENANT-ID>/v2.0",
      client_auth_method: "query",
      discovery: true,
      uid_field: "oid",
      send_scope_to_token_endpoint: "false",
      client_options: {
        identifier: "<YOUR APP CLIENT ID>",
        secret: "<YOUR APP CLIENT SECRET>",
        redirect_uri: "https://gitlab.example.com/users/auth/azure_activedirectory_v2/callback"
      }
    }
  }
]

::EndTabs

For Helm installations:

Add the provider's configuration in a YAML file (for example, provider.yaml):

::Tabs

:::TabTitle Azure OAuth 2.0

{
  "name": "azure_oauth2",
  "args": {
    "name": "azure_oauth2",
    "strategy_class": "OmniAuth::Strategies::OpenIDConnect",
    "scope": [
      "openid",
      "profile",
      "email"
    ],
    "response_type": "code",
    "issuer": "https://login.microsoftonline.com/<YOUR-TENANT-ID>/v2.0",
    "client_auth_method": "query",
    "discovery": true,
    "uid_field": "sub",
    "send_scope_to_token_endpoint": false,
    "client_options": {
      "identifier": "<YOUR APP CLIENT ID>",
      "secret": "<YOUR APP CLIENT SECRET>",
      "redirect_uri": "https://gitlab.example.com/users/auth/azure_oauth2/callback"
    }
  }
}

:::TabTitle Azure Active Directory v2

{
  "name": "azure_activedirectory_v2",
  "args": {
    "name": "azure_activedirectory_v2",
    "strategy_class": "OmniAuth::Strategies::OpenIDConnect",
    "scope": [
      "openid",
      "profile",
      "email"
    ],
    "response_type": "code",
    "issuer": "https://login.microsoftonline.com/<YOUR-TENANT-ID>/v2.0",
    "client_auth_method": "query",
    "discovery": true,
    "uid_field": "sub",
    "send_scope_to_token_endpoint": false,
    "client_options": {
      "identifier": "<YOUR APP CLIENT ID>",
      "secret": "<YOUR APP CLIENT SECRET>",
      "redirect_uri": "https://gitlab.example.com/users/auth/activedirectory_v2/callback"
    }
  }
}

::EndTabs

As you migrate from azure_oauth2 to omniauth_openid_connect as part of upgrading to GitLab 17.0 or above, the sub claim value set for your organization can vary. azure_oauth2 uses Microsoft V1 endpoint while azure_activedirectory_v2 and omniauth_openid_connect both use Microsoft V2 endpoint with a common sub value.

For users with an email address in Entra ID, to allow falling back to email address and updating the user's identity, configure the following:
- In a Linux package installation, omniauth_auto_link_user.
- In a Helm installation, autoLinkUser.
For users with no email address, administrators must take one of the following actions:
- Set up another authentication method or enable sign-in using GitLab username and password. The user can then sign in and link their Azure identity manually using their profile.
- Implement OpenID Connect as a new provider alongside the existing azure_oauth2 so the user can sign in through OAuth2, and link their OpenID Connect identity (similar to the previous method). This method would also work for users with email addresses, as long as auto_link_user is enabled.
- Update extern_uid manually. To do this, use the API or Rails console to update the extern_uid for each user. This method may be required if the instance has already been upgraded to 17.0 or later, and users have attempted to sign in.

NOTE: azure_oauth2 might have used Entra ID's upn claim as the email address, if the email claim was missing or blank when provisioning GitLab accounts.

Configure Microsoft Azure Active Directory B2C

GitLab requires special configuration to work with Azure Active Directory B2C. To get started, sign in to the Azure Portal. For your app, you need the following information from Azure:

A tenant ID. You may already have one. For more information, review the Microsoft Azure Tenant documentation.
A client ID and a client secret. Follow the instructions in the Microsoft tutorial documentation to obtain the client ID and client secret for your app.
The user flow or policy name. Follow the instructions in the Microsoft tutorial.

Configure the app:

Set the app Redirect URI. For example, If your GitLab domain is gitlab.example.com, set the app Redirect URI to https://gitlab.example.com/users/auth/openid_connect/callback.
Enable the ID tokens.
Add the following API permissions to the app:
- openid
- offline_access

Configure custom policies

Azure B2C offers two ways of defining the business logic for logging in a user:

Custom policies are required because standard Azure B2C user flows do not send the OpenID email claim. Therefore, the standard user flows do not work with the allow_single_sign_on or auto_link_user parameters. With a standard Azure B2C policy, GitLab cannot create a new account or link to an existing account with an email address.

First, create a custom policy.

The Microsoft instructions use SocialAndLocalAccounts in the custom policy starter pack, but LocalAccounts authenticates against local Active Directory accounts. Before you upload the polices, do the following:

To export the email claim, modify the SignUpOrSignin.xml. Replace the following line:

<OutputClaim ClaimTypeReferenceId="email" />

with:

<OutputClaim ClaimTypeReferenceId="signInNames.emailAddress" PartnerClaimType="email" />

For OIDC discovery to work with B2C, configure the policy with an issuer compatible with the OIDC specification. See the token compatibility settings. In TrustFrameworkBase.xml under JwtIssuer, set IssuanceClaimPattern to AuthorityWithTfp:

<ClaimsProvider>
  <DisplayName>Token Issuer</DisplayName>
  <TechnicalProfiles>
    <TechnicalProfile Id="JwtIssuer">
      <DisplayName>JWT Issuer</DisplayName>
      <Protocol Name="None" />
      <OutputTokenFormat>JWT</OutputTokenFormat>
      <Metadata>
        <Item Key="IssuanceClaimPattern">AuthorityWithTfp</Item>
        ...

Upload the policy. Overwrite the existing files if you are updating an existing policy.
To determine the issuer URL, use the sign-in policy. The issuer URL is in the form:
```
https://<YOUR-DOMAIN>/tfp/<YOUR-TENANT-ID>/<YOUR-SIGN-IN-POLICY-NAME>/v2.0/
```
The policy name is lowercase in the URL. For example, B2C_1A_signup_signin policy appears as b2c_1a_signup_sigin.

Ensure you include the trailing forward slash.

Verify the operation of the OIDC discovery URL and issuer URL and append .well-known/openid-configuration to the issuer URL:

https://<YOUR-DOMAIN>/tfp/<YOUR-TENANT-ID>/<YOUR-SIGN-IN-POLICY-NAME>/v2.0/.well-known/openid-configuration

For example, if domain is example.b2clogin.com and tenant ID is fc40c736-476c-4da1-b489-ee48cee84386, you can use curl and jq to extract the issuer:

$ curl --silent "https://example.b2clogin.com/tfp/fc40c736-476c-4da1-b489-ee48cee84386/b2c_1a_signup_signin/v2.0/.well-known/openid-configuration" | jq .issuer
"https://example.b2clogin.com/tfp/fc40c736-476c-4da1-b489-ee48cee84386/b2c_1a_signup_signin/v2.0/"

Configure the issuer URL with the custom policy used for signup_signin. For example, this is the configuration with a custom policy for b2c_1a_signup_signin for Linux package installations:

gitlab_rails['omniauth_providers'] = [
{
  name: "openid_connect", # do not change this parameter
  label: "Azure B2C OIDC", # optional label for login button, defaults to "Openid Connect"
  args: {
    name: "openid_connect",
    scope: ["openid"],
    response_mode: "query",
    response_type: "id_token",
    issuer:  "https://<YOUR-DOMAIN>/tfp/<YOUR-TENANT-ID>/b2c_1a_signup_signin/v2.0/",
    client_auth_method: "query",
    discovery: true,
    send_scope_to_token_endpoint: true,
    pkce: true,
    client_options: {
      identifier: "<YOUR APP CLIENT ID>",
      secret: "<YOUR APP CLIENT SECRET>",
      redirect_uri: "https://gitlab.example.com/users/auth/openid_connect/callback"
    }
  }
}]

Troubleshooting Azure B2C

Ensure all occurrences of yourtenant.onmicrosoft.com, ProxyIdentityExperienceFrameworkAppId, and IdentityExperienceFrameworkAppId match your B2C tenant hostname and the respective client IDs in the XML policy files.
Add https://jwt.ms as a redirect URI to the app, and use the custom policy tester. Ensure the payload includes email that matches the user's email access.
After you enable the custom policy, users might see Invalid username or password after they try to sign in. This might be a configuration issue with the IdentityExperienceFramework app. See this Microsoft comment that suggests you check that the app manifest contains these settings:
- "accessTokenAcceptedVersion": null
- "signInAudience": "AzureADMyOrg"

This configuration corresponds with the Supported account types setting used when creating the IdentityExperienceFramework app.

Configure Keycloak

GitLab works with OpenID providers that use HTTPS. Although you can set up a Keycloak server that uses HTTP, GitLab can only communicate with a Keycloak server that uses HTTPS.

Configure Keycloak to use public key encryption algorithms (for example, RSA256 or RSA512) instead of symmetric key encryption algorithms (for example, HS256 or HS358) to sign tokens. Public key encryption algorithms are:

Easier to configure.
More secure because leaking the private key has severe security consequences.

Open the Keycloak administration console.
Select Realm Settings > Tokens > Default Signature Algorithm.
Configure the signature algorithm.

Example configuration block for Linux package installations:

gitlab_rails['omniauth_providers'] = [
  {
    name: "openid_connect", # do not change this parameter
    label: "Keycloak", # optional label for login button, defaults to "Openid Connect"
    args: {
      name: "openid_connect",
      scope: ["openid", "profile", "email"],
      response_type: "code",
      issuer:  "https://keycloak.example.com/realms/myrealm",
      client_auth_method: "query",
      discovery: true,
      uid_field: "preferred_username",
      pkce: true,
      client_options: {
        identifier: "<YOUR CLIENT ID>",
        secret: "<YOUR CLIENT SECRET>",
        redirect_uri: "https://gitlab.example.com/users/auth/openid_connect/callback"
      }
    }
  }
]

Configure Keycloak with a symmetric key algorithm

WARNING: The following instructions are included for completeness, but only use symmetric key encryption if absolutely necessary.

To use symmetric key encryption:

Extract the secret key from the Keycloak database. Keycloak does not expose this value in the web interface. The client secret seen in the web interface is the OAuth 2.0 client secret, which is different from the secret used to sign JSON Web Tokens.

For example, if you use PostgreSQL as the backend database for Keycloak:

Run the following SQL query to extract the key:

$ psql -U keycloak
psql (13.3 (Debian 13.3-1.pgdg100+1))
Type "help" for help.

keycloak=# SELECT c.name, value FROM component_config CC INNER JOIN component C ON(CC.component_id = C.id) WHERE C.realm_id = 'master' and provider_id = 'hmac-generated' AND CC.name = 'secret';
-[ RECORD 1 ]---------------------------------------------------------------------------------
name  | hmac-generated
value | lo6cqjD6Ika8pk7qc3fpFx9ysrhf7E62-sqGc8drp3XW-wr93zru8PFsQokHZZuJJbaUXvmiOftCZM3C4KW3-g
-[ RECORD 2 ]---------------------------------------------------------------------------------
name  | fallback-HS384
value | UfVqmIs--U61UYsRH-NYBH3_mlluLONpg_zN7CXEwkJcO9xdRNlzZfmfDLPtf2xSTMvqu08R2VhLr-8G-oZ47A

In this example, there are two private keys: one for HS256 (hmac-generated) and another for HS384 (fallback-HS384). We use the first value to configure GitLab.

Convert value to standard base64. As discussed in the Invalid signature with HS256 token post, value is encoded in the Base 64 Encoding with URL and Filename Safe Alphabet section of RFC 4648. This must be converted to standard base64 as defined in RFC 2045. The following Ruby script does this:
```
require 'base64'

value = "lo6cqjD6Ika8pk7qc3fpFx9ysrhf7E62-sqGc8drp3XW-wr93zru8PFsQokHZZuJJbaUXvmiOftCZM3C4KW3-g"
Base64.encode64(Base64.urlsafe_decode64(value))
```
This results in the following value:
```
lo6cqjD6Ika8pk7qc3fpFx9ysrhf7E62+sqGc8drp3XW+wr93zru8PFsQokH\nZZuJJbaUXvmiOftCZM3C4KW3+g==\n
```

Specify this base64-encoded secret in jwt_secret_base64. For example:

gitlab_rails['omniauth_providers'] = [
  {
    name: "openid_connect", # do not change this parameter
    label: "Keycloak", # optional label for login button, defaults to "Openid Connect"
    args: {
      name: "openid_connect",
      scope: ["openid", "profile", "email"],
      response_type: "code",
      issuer:  "https://keycloak.example.com/auth/realms/myrealm",
      client_auth_method: "query",
      discovery: true,
      uid_field: "preferred_username",
      jwt_secret_base64: "<YOUR BASE64-ENCODED SECRET>",
      pkce: true,
      client_options: {
        identifier: "<YOUR CLIENT ID>",
        secret: "<YOUR CLIENT SECRET>",
        redirect_uri: "https://gitlab.example.com/users/auth/openid_connect/callback"
      }
    }
  }
]

If you see a JSON::JWS::VerificationFailed error, you have specified the wrong secret.

Casdoor

GitLab works with OpenID providers that use HTTPS. Use HTTPS to connect to GitLab through OpenID with Casdoor.

For your app, complete the following steps on Casdoor:

Get a client ID and a client secret.
Add your GitLab redirect URL. For example, if your GitLab domain is gitlab.example.com, ensure the Casdoor app has the following Redirect URI: https://gitlab.example.com/users/auth/openid_connect/callback.

See the Casdoor documentation for more details.

Example configuration for Linux package installations (file path: /etc/gitlab/gitlab.rb):

gitlab_rails['omniauth_providers'] = [
    {
        name: "openid_connect", # do not change this parameter
        label: "Casdoor", # optional label for login button, defaults to "Openid Connect"
        args: {
            name: "openid_connect",
            scope: ["openid", "profile", "email"],
            response_type: "code",
            issuer:  "https://<CASDOOR_HOSTNAME>",
            client_auth_method: "query",
            discovery: true,
            uid_field: "sub",
            client_options: {
                identifier: "<YOUR CLIENT ID>",
                secret: "<YOUR CLIENT SECRET>",
                redirect_uri: "https://gitlab.example.com/users/auth/openid_connect/callback"
            }
        }
    }
]

Example configuration for self-compiled installations (file path: config/gitlab.yml):

  - { name: 'openid_connect', # do not change this parameter
      label: 'Casdoor', # optional label for login button, defaults to "Openid Connect"
      args: {
        name: 'openid_connect',
        scope: ['openid','profile','email'],
        response_type: 'code',
        issuer: 'https://<CASDOOR_HOSTNAME>',
        discovery: true,
        client_auth_method: 'query',
        uid_field: 'sub',
        client_options: {
          identifier: '<YOUR CLIENT ID>',
          secret: '<YOUR CLIENT SECRET>',
          redirect_uri: 'https://gitlab.example.com/users/auth/openid_connect/callback'
        }
      }
    }

Configure multiple OpenID Connect providers

You can configure your application to use multiple OpenID Connect (OIDC) providers. You do this by explicitly setting the strategy_class in your configuration file.

You should do this in either of the following scenarios:

Migrating to the OpenID Connect protocol.
Offering different levels of authentication.

NOTE: This is not compatible with configuring users based on OIDC group membership. For more information, see issue 408248.

The following example configurations show how to offer different levels of authentication, one option with 2FA and one without 2FA.

For Linux package installations:

gitlab_rails['omniauth_providers'] = [
  {
    name: "openid_connect",
    label: "Provider name", # optional label for login button, defaults to "Openid Connect"
    icon: "<custom_provider_icon>",
    args: {
      name: "openid_connect",
      strategy_class: "OmniAuth::Strategies::OpenIDConnect",
      scope: ["openid","profile","email"],
      response_type: "code",
      issuer: "<your_oidc_url>",
      discovery: true,
      client_auth_method: "query",
      uid_field: "<uid_field>",
      send_scope_to_token_endpoint: "false",
      pkce: true,
      client_options: {
        identifier: "<your_oidc_client_id>",
        secret: "<your_oidc_client_secret>",
        redirect_uri: "<your_gitlab_url>/users/auth/openid_connect/callback"
      }
    }
  },
  {
    name: "openid_connect_2fa",
    label: "Provider name 2FA", # optional label for login button, defaults to "Openid Connect"
    icon: "<custom_provider_icon>",
    args: {
      name: "openid_connect_2fa",
      strategy_class: "OmniAuth::Strategies::OpenIDConnect",
      scope: ["openid","profile","email"],
      response_type: "code",
      issuer: "<your_oidc_url>",
      discovery: true,
      client_auth_method: "query",
      uid_field: "<uid_field>",
      send_scope_to_token_endpoint: "false",
      pkce: true,
      client_options: {
        identifier: "<your_oidc_client_id>",
        secret: "<your_oidc_client_secret>",
        redirect_uri: "<your_gitlab_url>/users/auth/openid_connect_2fa/callback"
      }
    }
  }
]

For self-compiled installations:

  - { name: 'openid_connect',
      label: 'Provider name', # optional label for login button, defaults to "Openid Connect"
      icon: '<custom_provider_icon>',
      args: {
        name: 'openid_connect',
        strategy_class: "OmniAuth::Strategies::OpenIDConnect",
        scope: ['openid','profile','email'],
        response_type: 'code',
        issuer: '<your_oidc_url>',
        discovery: true,
        client_auth_method: 'query',
        uid_field: '<uid_field>',
        send_scope_to_token_endpoint: false,
        pkce: true,
        client_options: {
          identifier: '<your_oidc_client_id>',
          secret: '<your_oidc_client_secret>',
          redirect_uri: '<your_gitlab_url>/users/auth/openid_connect/callback'
        }
      }
    }
  - { name: 'openid_connect_2fa',
      label: 'Provider name 2FA', # optional label for login button, defaults to "Openid Connect"
      icon: '<custom_provider_icon>',
      args: {
        name: 'openid_connect_2fa',
        strategy_class: "OmniAuth::Strategies::OpenIDConnect",
        scope: ['openid','profile','email'],
        response_type: 'code',
        issuer: '<your_oidc_url>',
        discovery: true,
        client_auth_method: 'query',
        uid_field: '<uid_field>',
        send_scope_to_token_endpoint: false,
        pkce: true,
        client_options: {
          identifier: '<your_oidc_client_id>',
          secret: '<your_oidc_client_secret>',
          redirect_uri: '<your_gitlab_url>/users/auth/openid_connect_2fa/callback'
        }
      }
    }

In this use case, you might want to synchronize the extern_uid across the different providers based on an existing known identifier in your corporate directory.

To do this, you set the uid_field. The following example code shows how to do this:

def sync_missing_provider(self, user: User, extern_uid: str)
  existing_identities = []
  for identity in user.identities:
      existing_identities.append(identity.get("provider"))

  local_extern_uid = extern_uid.lower()
  for provider in ("openid_connect_2fa", "openid_connect"):
      identity = [
          identity
          for identity in user.identities
          if identity.get("provider") == provider
          and identity.get("extern_uid").lower() != local_extern_uid
      ]
      if provider not in existing_identities or identity:
          if identity and identity[0].get("extern_uid") != "":
              logger.error(f"Found different identity for provider {provider} for user {user.id}")
              continue
          else:
              logger.info(f"Add identity 'provider': {provider}, 'extern_uid': {extern_uid} for user {user.id}")
              user.provider = provider
              user.extern_uid = extern_uid
              user = self.save_user(user)
  return user

For more information, see the GitLab API user method documentation.

Configure users based on OIDC group membership

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

Introduced in GitLab 15.10.

You can configure OIDC group membership to:

Require users to be members of a certain group.
Assign users external, administrator or auditor roles based on group membership.

GitLab checks these groups on each sign in and updates user attributes as necessary. This feature does not allow you to automatically add users to GitLab groups.

Required groups

Your identity provider (IdP) must pass group information to GitLab in the OIDC response. To use this response to require users to be members of a certain group, configure GitLab to identify:

Where to look for the groups in the OIDC response, using the groups_attribute setting.
Which group membership is required to sign in, using the required_groups setting.

If you do not set required_groups or leave the setting empty, any user authenticated by the IdP through OIDC can use GitLab.

::Tabs

:::TabTitle Linux package (Omnibus)

Edit /etc/gitlab/gitlab.rb:

gitlab_rails['omniauth_providers'] = [
  {
    name: "openid_connect",
    label: "Provider name",
    args: {
      name: "openid_connect",
      scope: ["openid","profile","email"],
      response_type: "code",
      issuer: "<your_oidc_url>",
      discovery: true,
      client_auth_method: "query",
      uid_field: "<uid_field>",
      client_options: {
        identifier: "<your_oidc_client_id>",
        secret: "<your_oidc_client_secret>",
        redirect_uri: "<your_gitlab_url>/users/auth/openid_connect/callback",
        gitlab: {
          groups_attribute: "groups",
          required_groups: ["Developer"]
        }
      }
    }
  }
]

Save the file and reconfigure GitLab for the changes to take effect.

:::TabTitle Self-compiled (source)

Edit /home/git/gitlab/config/gitlab.yml:

production: &base
  omniauth:
    providers:
     - { name: 'openid_connect',
         label: 'Provider name',
      args: {
        name: 'openid_connect',
        scope: ['openid','profile','email'],
        response_type: 'code',
        issuer: '<your_oidc_url>',
        discovery: true,
        client_auth_method: 'query',
        uid_field: '<uid_field>',
        client_options: {
          identifier: '<your_oidc_client_id>',
          secret: '<your_oidc_client_secret>',
          redirect_uri: '<your_gitlab_url>/users/auth/openid_connect/callback',
          gitlab: {
            groups_attribute: "groups",
            required_groups: ["Developer"]
          }
        }
      }
    }

Save the file and reconfigure GitLab for the changes to take effect.

::EndTabs

External groups

Your IdP must pass group information to GitLab in the OIDC response. To use this response to identify users as external users based on group membership, configure GitLab to identify:

Where to look for the groups in the OIDC response, using the groups_attribute setting.
Which group memberships should identify a user as an external user, using the external_groups setting.

::Tabs

:::TabTitle Linux package (Omnibus)

Edit /etc/gitlab/gitlab.rb:

gitlab_rails['omniauth_providers'] = [
  {
    name: "openid_connect",
    label: "Provider name",
    args: {
      name: "openid_connect",
      scope: ["openid","profile","email"],
      response_type: "code",
      issuer: "<your_oidc_url>",
      discovery: true,
      client_auth_method: "query",
      uid_field: "<uid_field>",
      client_options: {
        identifier: "<your_oidc_client_id>",
        secret: "<your_oidc_client_secret>",
        redirect_uri: "<your_gitlab_url>/users/auth/openid_connect/callback",
        gitlab: {
          groups_attribute: "groups",
          external_groups: ["Freelancer"]
        }
      }
    }
  }
]

Save the file and reconfigure GitLab for the changes to take effect.

:::TabTitle Self-compiled (source)

Edit /home/git/gitlab/config/gitlab.yml:

production: &base
  omniauth:
    providers:
     - { name: 'openid_connect',
         label: 'Provider name',
      args: {
        name: 'openid_connect',
        scope: ['openid','profile','email'],
        response_type: 'code',
        issuer: '<your_oidc_url>',
        discovery: true,
        client_auth_method: 'query',
        uid_field: '<uid_field>',
        client_options: {
          identifier: '<your_oidc_client_id>',
          secret: '<your_oidc_client_secret>',
          redirect_uri: '<your_gitlab_url>/users/auth/openid_connect/callback',
          gitlab: {
            groups_attribute: "groups",
            external_groups: ["Freelancer"]
          }
        }
      }
    }

Save the file and reconfigure GitLab for the changes to take effect.

::EndTabs

Auditor groups

DETAILS: Tier: Premium, Ultimate Offering: Self-managed

Your IdP must pass group information to GitLab in the OIDC response. To use this response to assign users as auditors based on group membership, configure GitLab to identify:

Where to look for the groups in the OIDC response, using the groups_attribute setting.
Which group memberships grant the user auditor access, using the auditor_groups setting.

::Tabs

:::TabTitle Linux package (Omnibus)

Edit /etc/gitlab/gitlab.rb:

gitlab_rails['omniauth_providers'] = [
  {
    name: "openid_connect",
    label: "Provider name",
    args: {
      name: "openid_connect",
      scope: ["openid","profile","email","groups"],
      response_type: "code",
      issuer: "<your_oidc_url>",
      discovery: true,
      client_auth_method: "query",
      uid_field: "<uid_field>",
      client_options: {
        identifier: "<your_oidc_client_id>",
        secret: "<your_oidc_client_secret>",
        redirect_uri: "<your_gitlab_url>/users/auth/openid_connect/callback",
        gitlab: {
          groups_attribute: "groups",
          auditor_groups: ["Auditor"]
        }
      }
    }
  }
]

Save the file and reconfigure GitLab for the changes to take effect.

:::TabTitle Self-compiled (source)

Edit /home/git/gitlab/config/gitlab.yml:

production: &base
  omniauth:
    providers:
     - { name: 'openid_connect',
         label: 'Provider name',
      args: {
        name: 'openid_connect',
        scope: ['openid','profile','email','groups'],
        response_type: 'code',
        issuer: '<your_oidc_url>',
        discovery: true,
        client_auth_method: 'query',
        uid_field: '<uid_field>',
        client_options: {
          identifier: '<your_oidc_client_id>',
          secret: '<your_oidc_client_secret>',
          redirect_uri: '<your_gitlab_url>/users/auth/openid_connect/callback',
          gitlab: {
            groups_attribute: "groups",
            auditor_groups: ["Auditor"]
          }
        }
      }
    }

Save the file and reconfigure GitLab for the changes to take effect.

::EndTabs

Administrator groups

Your IdP must pass group information to GitLab in the OIDC response. To use this response to assign users as administrator based on group membership, configure GitLab to identify:

Where to look for the groups in the OIDC response, using the groups_attribute setting.
Which group memberships grant the user administrator access, using the admin_groups setting.

::Tabs

:::TabTitle Linux package (Omnibus)

Edit /etc/gitlab/gitlab.rb:

gitlab_rails['omniauth_providers'] = [
  {
    name: "openid_connect",
    label: "Provider name",
    args: {
      name: "openid_connect",
      scope: ["openid","profile","email"],
      response_type: "code",
      issuer: "<your_oidc_url>",
      discovery: true,
      client_auth_method: "query",
      uid_field: "<uid_field>",
      client_options: {
        identifier: "<your_oidc_client_id>",
        secret: "<your_oidc_client_secret>",
        redirect_uri: "<your_gitlab_url>/users/auth/openid_connect/callback",
        gitlab: {
          groups_attribute: "groups",
          admin_groups: ["Admin"]
        }
      }
    }
  }
]

Save the file and reconfigure GitLab for the changes to take effect.

:::TabTitle Self-compiled (source)

Edit /home/git/gitlab/config/gitlab.yml:

production: &base
  omniauth:
    providers:
     - { name: 'openid_connect',
         label: 'Provider name',
      args: {
        name: 'openid_connect',
        scope: ['openid','profile','email'],
        response_type: 'code',
        issuer: '<your_oidc_url>',
        discovery: true,
        client_auth_method: 'query',
        uid_field: '<uid_field>',
        client_options: {
          identifier: '<your_oidc_client_id>',
          secret: '<your_oidc_client_secret>',
          redirect_uri: '<your_gitlab_url>/users/auth/openid_connect/callback',
          gitlab: {
            groups_attribute: "groups",
            admin_groups: ["Admin"]
          }
        }
      }
    }

Save the file and reconfigure GitLab for the changes to take effect.

::EndTabs

Troubleshooting

Ensure discovery is set to true. If you set it to false, you must specify all the URLs and keys required to make OpenID work.
Check your system clock to ensure the time is synchronized properly.
As mentioned in the OmniAuth OpenID Connect documentation, make sure issuer corresponds to the base URL of the Discovery URL. For example, https://accounts.google.com is used for the URL https://accounts.google.com/.well-known/openid-configuration.
The OpenID Connect client uses HTTP Basic Authentication to send the OAuth 2.0 access token if client_auth_method is not defined or if set to basic. If you see 401 errors when retrieving the userinfo endpoint, check your OpenID web server configuration. For example, for oauth2-server-php, you may have to add a configuration parameter to Apache.