OAuth 2.0 identity provider API
DETAILS: Tier: Free, Premium, Ultimate Offering: GitLab.com, Self-managed, GitLab Dedicated
GitLab provides an API to allow third-party services to access GitLab resources on a user's behalf with the OAuth 2.0 protocol.
To configure GitLab for this, see Configure GitLab as an OAuth 2.0 authentication identity provider.
This functionality is based on the doorkeeper Ruby gem.
Cross-origin resource sharing
- CORS preflight request support introduced in GitLab 15.1.
Many /oauth
endpoints support cross-origin resource sharing (CORS). From GitLab 15.1, the following endpoints also
support CORS preflight requests:
/oauth/revoke
/oauth/token
/oauth/userinfo
Only certain headers can be used for preflight requests:
- The headers listed for simple requests.
- The
Authorization
header.
For example, the X-Requested-With
header can't be used for preflight requests.
Supported OAuth 2.0 flows
GitLab supports the following authorization flows:
- Authorization code with Proof Key for Code Exchange (PKCE): Most secure. Without PKCE, you'd have to include client secrets on mobile clients, and is recommended for both client and server apps.
- Authorization code: Secure and common flow. Recommended option for secure server-side apps.
- Resource owner password credentials: To be used only for securely hosted, first-party services. GitLab recommends against use of this flow.
- Device Authorization Grant (GitLab 17.1 and later) Secure flow oriented toward devices without browser access. Requires a secondary device to complete the authorization flow.
The draft specification for OAuth 2.1 specifically omits both the Implicit grant and Resource Owner Password Credentials flows.
Refer to the OAuth RFC to find out how all those flows work and pick the right one for your use case.
Authorization code (with or without PKCE) flow requires application
to be
registered first via the /user_settings/applications
page in your user's account.
During registration, by enabling proper scopes, you can limit the range of
resources which the application
can access. Upon creation, you obtain the
application
credentials: Application ID and Client Secret. The Client Secret
must be kept secure. It is also advantageous to keep the Application ID
secret when your application architecture allows.
For a list of scopes in GitLab, see the provider documentation.
Prevent CSRF attacks
To protect redirect-based flows,
the OAuth specification recommends the use of "One-time use CSRF tokens carried in the state
parameter, which are securely bound to the user agent", with each request to the
/oauth/authorize
endpoint. This can prevent
CSRF attacks.
Use HTTPS in production
For production, use HTTPS for your redirect_uri
.
For development, GitLab allows insecure HTTP redirect URIs.
As OAuth 2.0 bases its security entirely on the transport layer, you should not use unprotected URIs. For more information, see the OAuth 2.0 RFC and the OAuth 2.0 Threat Model RFC.
In the following sections you can find detailed instructions on how to obtain authorization with each flow.
Authorization code with Proof Key for Code Exchange (PKCE)
The PKCE RFC includes a detailed flow description, from authorization request through access token. The following steps describe our implementation of the flow.
The Authorization code with PKCE flow, PKCE for short, makes it possible to securely perform the OAuth exchange of client credentials for access tokens on public clients without requiring access to the Client Secret at all. This makes the PKCE flow advantageous for single page JavaScript applications or other client side apps where keeping secrets from the user is a technical impossibility.
Before starting the flow, generate the STATE
, the CODE_VERIFIER
and the CODE_CHALLENGE
.
- The
STATE
a value that can't be predicted used by the client to maintain state between the request and callback. It should also be used as a CSRF token. - The
CODE_VERIFIER
is a random string, between 43 and 128 characters in length, which use the charactersA-Z
,a-z
,0-9
,-
,.
,_
, and~
. - The
CODE_CHALLENGE
is an URL-safe base64-encoded string of the SHA256 hash of theCODE_VERIFIER
:- The SHA256 hash must be in binary format before encoding.
- In Ruby, you can set that up with
Base64.urlsafe_encode64(Digest::SHA256.digest(CODE_VERIFIER), padding: false)
. - For reference, a
CODE_VERIFIER
string ofks02i3jdikdo2k0dkfodf3m39rjfjsdk0wk349rj3jrhf
when hashed and encoded using the Ruby snippet above produces aCODE_CHALLENGE
string of2i0WFA-0AerkjQm4X4oDEhqA17QIAKNjXpagHBXmO_U
.
-
Request authorization code. To do that, you should redirect the user to the
/oauth/authorize
page with the following query parameters:https://gitlab.example.com/oauth/authorize?client_id=APP_ID&redirect_uri=REDIRECT_URI&response_type=code&state=STATE&scope=REQUESTED_SCOPES&code_challenge=CODE_CHALLENGE&code_challenge_method=S256
This page asks the user to approve the request from the app to access their account based on the scopes specified in
REQUESTED_SCOPES
. The user is then redirected back to the specifiedREDIRECT_URI
. The scope parameter is a space-separated list of scopes associated with the user. For example,scope=read_user+profile
requests theread_user
andprofile
scopes. The redirect includes the authorizationcode
, for example:https://example.com/oauth/redirect?code=1234567890&state=STATE
-
With the authorization
code
returned from the previous request (denoted asRETURNED_CODE
in the following example), you can request anaccess_token
, with any HTTP client. The following example uses Ruby'srest-client
:parameters = 'client_id=APP_ID&code=RETURNED_CODE&grant_type=authorization_code&redirect_uri=REDIRECT_URI&code_verifier=CODE_VERIFIER' RestClient.post 'https://gitlab.example.com/oauth/token', parameters
Example response:
{ "access_token": "de6780bc506a0446309bd9362820ba8aed28aa506c71eedbe1c5c4f9dd350e54", "token_type": "bearer", "expires_in": 7200, "refresh_token": "8257e65c97202ed1726cf9571600918f3bffb2544b26e00a61df9897668c33a1", "created_at": 1607635748 }
-
To retrieve a new
access_token
, use therefresh_token
parameter. Refresh tokens may be used even after theaccess_token
itself expires. This request:- Invalidates the existing
access_token
andrefresh_token
. - Sends new tokens in the response.
parameters = 'client_id=APP_ID&refresh_token=REFRESH_TOKEN&grant_type=refresh_token&redirect_uri=REDIRECT_URI&code_verifier=CODE_VERIFIER' RestClient.post 'https://gitlab.example.com/oauth/token', parameters
Example response:
{ "access_token": "c97d1fe52119f38c7f67f0a14db68d60caa35ddc86fd12401718b649dcfa9c68", "token_type": "bearer", "expires_in": 7200, "refresh_token": "803c1fd487fec35562c205dac93e9d8e08f9d3652a24079d704df3039df1158f", "created_at": 1628711391 }
- Invalidates the existing
NOTE:
The redirect_uri
must match the redirect_uri
used in the original
authorization request.
You can now make requests to the API with the access token.
Authorization code flow
NOTE: Check the RFC spec for a detailed flow description.
The authorization code flow is essentially the same as authorization code flow with PKCE,
Before starting the flow, generate the STATE
. It is a value that can't be predicted
used by the client to maintain state between the request and callback. It should also
be used as a CSRF token.
-
Request authorization code. To do that, you should redirect the user to the
/oauth/authorize
page with the following query parameters:https://gitlab.example.com/oauth/authorize?client_id=APP_ID&redirect_uri=REDIRECT_URI&response_type=code&state=STATE&scope=REQUESTED_SCOPES
This page asks the user to approve the request from the app to access their account based on the scopes specified in
REQUESTED_SCOPES
. The user is then redirected back to the specifiedREDIRECT_URI
. The scope parameter is a space-separated list of scopes associated with the user. For example,scope=read_user+profile
requests theread_user
andprofile
scopes. The redirect includes the authorizationcode
, for example:https://example.com/oauth/redirect?code=1234567890&state=STATE
-
With the authorization
code
returned from the previous request (shown asRETURNED_CODE
in the following example), you can request anaccess_token
, with any HTTP client. The following example uses Ruby'srest-client
:parameters = 'client_id=APP_ID&client_secret=APP_SECRET&code=RETURNED_CODE&grant_type=authorization_code&redirect_uri=REDIRECT_URI' RestClient.post 'https://gitlab.example.com/oauth/token', parameters
Example response:
{ "access_token": "de6780bc506a0446309bd9362820ba8aed28aa506c71eedbe1c5c4f9dd350e54", "token_type": "bearer", "expires_in": 7200, "refresh_token": "8257e65c97202ed1726cf9571600918f3bffb2544b26e00a61df9897668c33a1", "created_at": 1607635748 }
-
To retrieve a new
access_token
, use therefresh_token
parameter. Refresh tokens may be used even after theaccess_token
itself expires. This request:- Invalidates the existing
access_token
andrefresh_token
. - Sends new tokens in the response.
parameters = 'client_id=APP_ID&client_secret=APP_SECRET&refresh_token=REFRESH_TOKEN&grant_type=refresh_token&redirect_uri=REDIRECT_URI' RestClient.post 'https://gitlab.example.com/oauth/token', parameters
Example response:
{ "access_token": "c97d1fe52119f38c7f67f0a14db68d60caa35ddc86fd12401718b649dcfa9c68", "token_type": "bearer", "expires_in": 7200, "refresh_token": "803c1fd487fec35562c205dac93e9d8e08f9d3652a24079d704df3039df1158f", "created_at": 1628711391 }
- Invalidates the existing
NOTE:
The redirect_uri
must match the redirect_uri
used in the original
authorization request.
You can now make requests to the API with the access token returned.
Device authorization grant flow
- Introduced in GitLab 17.2 with a flag named
oauth2_device_grant_flow
.- Enabled by default in 17.3.
FLAG: The availability of this feature is controlled by a feature flag. For more information, see the history.
NOTE: Check the RFC spec for a detailed description of the device authorization grant flow, from device authorization request to token response from the browser login.
The device authorization grant flow makes it possible to securely authenticate your GitLab identity from input constrained devices where browser interactions are not an option.
This makes the device authorization grant flow ideal for users attempting to use GitLab services from headless servers or other devices with no, or limited, UI.
-
To request device authorization, a request is sent from the input-limited device client to
https://gitlab.example.com/oauth/authorize_device
. For example:parameters = 'client_id=UID&scope=read' RestClient.post 'https://gitlab.example.com/oauth/authorize_device', parameters
After a successful request, a response containing a
verification_uri
is returned to the user. For example:{ "device_code": "GmRhmhcxhwAzkoEqiMEg_DnyEysNkuNhszIySk9eS", "user_code": "0A44L90H", "verification_uri": "https://gitlab.example.com/oauth/device", "verification_uri_complete": "https://gitlab.example.com/oauth/device?user_code=0A44L90H", "expires_in": 300, "interval": 5 }
-
The device client displays the
user_code
andverification_uri
from the response to the requesting user. That user then, on a secondary device with browser access:- Goes to the provided URI.
- Enters the user code.
- Completes an authentication as prompted.
-
Immediately after displaying the
verification_uri
anduser_code
, the device client begins polling the token endpoint with the associateddevice_code
returned in the initial response:parameters = 'grant_type=urn:ietf:params:oauth:grant-type:device_code &device_code=GmRhmhcxhwAzkoEqiMEg_DnyEysNkuNhszIySk9eS &client_id=1406020730' RestClient.post 'https://gitlab.example.com/oauth/token', parameters
-
The device client receives a response from the token endpoint. If the authorization was successful, a success response is returned, otherwise, an error response is returned. Potential error responses are categorized by either of the following:
- Those defined by the OAuth Authorization Framework access token error responses.
- Those specific to the device authorization grant flow described here. Those error responses specific to the device flow are described in the following content. For more information on each potential response, see the relevant RFC spec for device authorization grant and the RFC spec for authorization tokens.
Example response:
{ "error": "authorization_pending", "error_description": "..." }
On receipt of this response, the device client continues polling.
If the polling interval is too short, a slow down error response is returned. For example:
{ "error": "slow_down", "error_description": "..." }
On receipt of this response, the device client reduces its polling rate and continues polling at the new rate.
If the device code expires before authentication is complete, an expired token error response is returned. For example:
{ "error": "expired_token", "error_description": "..." }
At that point, the device-client should stop and initiate a new device authorization request.
If the authorization request was denied, an access denied error response is returned. For example:
{ "error": "access_denied", "error_description": "..." }
The authentication request has been rejected. The user should verify their credentials or contact their system administrator
-
After the user successfully authenticates, a success response is returned:
{ "access_token": "TOKEN", "token_type": "Bearer", "expires_in": 7200, "scope": "read", "created_at": 1593096829 }
At this point, the device authentication flow is complete. The returned access_token
can be provided to GitLab to authenticate the user identity when accessing GitLab resources, such as when cloning over HTTPS or accessing the API.
A sample application that implements the client side device flow can be found at: https://gitlab.com/johnwparent/git-auth-over-https.
Resource owner password credentials flow
NOTE: Check the RFC spec for a detailed flow description.
NOTE: The Resource Owner Password Credentials is disabled for users with two-factor authentication turned on. These users can access the API using personal access tokens instead.
NOTE: Ensure the Allow password authentication for Git over HTTP(S) checkbox is selected for the GitLab instance to support the password credentials flow.
In this flow, a token is requested in exchange for the resource owner credentials (username and password).
The credentials should only be used when:
- There is a high degree of trust between the resource owner and the client. For example, the client is part of the device operating system or a highly privileged application.
- Other authorization grant types are not available (such as an authorization code).
WARNING: Never store the user's credentials and only use this grant type when your client is deployed to a trusted environment, in 99% of cases personal access tokens are a better choice.
Even though this grant type requires direct client access to the resource owner credentials, the resource owner credentials are used for a single request and are exchanged for an access token. This grant type can eliminate the need for the client to store the resource owner credentials for future use, by exchanging the credentials with a long-lived access token or refresh token.
To request an access token, you must make a POST request to /oauth/token
with
the following parameters:
{
"grant_type" : "password",
"username" : "user@example.com",
"password" : "secret"
}
Example cURL request:
echo 'grant_type=password&username=<your_username>&password=<your_password>' > auth.txt
curl --data "@auth.txt" --request POST "https://gitlab.example.com/oauth/token"
You can also use this grant flow with registered OAuth applications, by using
HTTP Basic Authentication with the application's client_id
and client_secret
:
echo 'grant_type=password&username=<your_username>&password=<your_password>' > auth.txt
curl --data "@auth.txt" --user client_id:client_secret \
--request POST "https://gitlab.example.com/oauth/token"
Then, you receive a response containing the access token:
{
"access_token": "1f0af717251950dbd4d73154fdf0a474a5c5119adad999683f5b450c460726aa",
"token_type": "bearer",
"expires_in": 7200
}
By default, the scope of the access token is api
, which provides complete read/write access.
For testing, you can use the oauth2
Ruby gem:
client = OAuth2::Client.new('the_client_id', 'the_client_secret', :site => "https://example.com")
access_token = client.password.get_token('user@example.com', 'secret')
puts access_token.token
access token
Access GitLab API with The access token
allows you to make requests to the API on behalf of a user.
You can pass the token either as GET parameter:
GET https://gitlab.example.com/api/v4/user?access_token=OAUTH-TOKEN
or you can put the token to the Authorization header:
curl --header "Authorization: Bearer OAUTH-TOKEN" "https://gitlab.example.com/api/v4/user"
access token
Access Git over HTTPS with A token with scope
read_repository
or write_repository
can access Git over HTTPS. Use the token as the password.
You can set the username to any string value. You should use oauth2
:
https://oauth2:<your_access_token>@gitlab.example.com/project_path/project_name.git
Alternatively, you can use a Git credential helper to authenticate to GitLab with OAuth. This handles OAuth token refresh automatically.
Retrieve the token information
To verify the details of a token, use the token/info
endpoint provided by the
Doorkeeper gem. For more information, see
/oauth/token/info
.
You must supply the access token, either:
-
As a parameter:
GET https://gitlab.example.com/oauth/token/info?access_token=<OAUTH-TOKEN>
-
In the Authorization header:
curl --header "Authorization: Bearer <OAUTH-TOKEN>" "https://gitlab.example.com/oauth/token/info"
The following is an example response:
{
"resource_owner_id": 1,
"scope": ["api"],
"expires_in": null,
"application": {"uid": "1cb242f495280beb4291e64bee2a17f330902e499882fe8e1e2aa875519cab33"},
"created_at": 1575890427
}
Deprecated fields
The fields scopes
and expires_in_seconds
are included in the response but are now deprecated. The scopes
field is an alias for scope
, and the expires_in_seconds
field is an alias for expires_in
. For more information, see Doorkeeper API changes.
Revoke a token
To revoke a token, use the revoke
endpoint. The API returns a 200 response code and an empty
JSON hash to indicate success.
parameters = 'client_id=APP_ID&client_secret=APP_SECRET&token=TOKEN'
RestClient.post 'https://gitlab.example.com/oauth/revoke', parameters
OAuth 2.0 tokens and GitLab registries
Standard OAuth 2.0 tokens support different degrees of access to GitLab registries, as they:
- Do not allow users to authenticate to:
- The GitLab container registry.
- Packages listed in the GitLab Package registry.
- Allow users to get, list, and delete registries through the container registry API.