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GitLab API

Automate GitLab via a simple and powerful API. All definitions can be found under /lib/api.

Resources

Documentation for various API resources can be found separately in the following locations:

Road to GraphQL

Going forward, we will start on moving to GraphQL and deprecate the use of controller-specific endpoints. GraphQL has a number of benefits:

  1. We avoid having to maintain two different APIs.
  2. Callers of the API can request only what they need.
  3. It is versioned by default.

It will co-exist with the current v4 REST API. If we have a v5 API, this should be a compatibility layer on top of GraphQL.

Although there were some patenting and licensing concerns with GraphQL, these have been resolved to our satisfaction by the relicensing of the reference implementations under MIT, and the use of the OWF license for the GraphQL specification.

Basic usage

API requests should be prefixed with api and the API version. The API version is defined in lib/api.rb. For example, the root of the v4 API is at /api/v4.

Example of a valid API request using cURL:

curl "https://gitlab.example.com/api/v4/projects"

The API uses JSON to serialize data. You don't need to specify .json at the end of an API URL.

Authentication

Most API requests require authentication, or will only return public data when authentication is not provided. For those cases where it is not required, this will be mentioned in the documentation for each individual endpoint. For example, the /projects/:id endpoint.

There are three ways to authenticate with the GitLab API:

  1. OAuth2 tokens
  2. Personal access tokens
  3. Session cookie

For admins who want to authenticate with the API as a specific user, or who want to build applications or scripts that do so, two options are available:

  1. Impersonation tokens
  2. Sudo

If authentication information is invalid or omitted, an error message will be returned with status code 401:

{
  "message": "401 Unauthorized"
}

OAuth2 tokens

You can use an OAuth2 token to authenticate with the API by passing it in either the access_token parameter or the Authorization header.

Example of using the OAuth2 token in a parameter:

curl https://gitlab.example.com/api/v4/projects?access_token=OAUTH-TOKEN

Example of using the OAuth2 token in a header:

curl --header "Authorization: Bearer OAUTH-TOKEN" https://gitlab.example.com/api/v4/projects

Read more about GitLab as an OAuth2 provider.

Personal access tokens

You can use a personal access token to authenticate with the API by passing it in either the private_token parameter or the Private-Token header.

Example of using the personal access token in a parameter:

curl https://gitlab.example.com/api/v4/projects?private_token=9koXpg98eAheJpvBs5tK

Example of using the personal access token in a header:

curl --header "Private-Token: 9koXpg98eAheJpvBs5tK" https://gitlab.example.com/api/v4/projects

Read more about personal access tokens.

Session cookie

When signing in to the main GitLab application, a _gitlab_session cookie is set. The API will use this cookie for authentication if it is present, but using the API to generate a new session cookie is currently not supported.

The primary user of this authentication method is the web frontend of GitLab itself, which can use the API as the authenticated user to get a list of their projects, for example, without needing to explicitly pass an access token.

Impersonation tokens

Introduced in GitLab 9.0. Needs admin permissions.

Impersonation tokens are a type of personal access token that can only be created by an admin for a specific user. They are a great fit if you want to build applications or scripts that authenticate with the API as a specific user.

They are an alternative to directly using the user's password or one of their personal access tokens, and to using the Sudo feature, since the user's (or admin's, in the case of Sudo) password/token may not be known or may change over time.

For more information, refer to the users API docs.

Impersonation tokens are used exactly like regular personal access tokens, and can be passed in either the private_token parameter or the Private-Token header.

Sudo

Needs admin permissions.

All API requests support performing an API call as if you were another user, provided you are authenticated as an administrator with an OAuth or Personal Access Token that has the sudo scope.

You need to pass the sudo parameter either via query string or a header with an ID/username of the user you want to perform the operation as. If passed as a header, the header name must be Sudo.

If a non administrative access token is provided, an error message will be returned with status code 403:

{
  "message": "403 Forbidden - Must be admin to use sudo"
}

If an access token without the sudo scope is provided, an error message will be returned with status code 403:

{
  "error": "insufficient_scope",
  "error_description": "The request requires higher privileges than provided by the access token.",
  "scope": "sudo"
}

If the sudo user ID or username cannot be found, an error message will be returned with status code 404:

{
  "message": "404 User with ID or username '123' Not Found"
}

Example of a valid API call and a request using cURL with sudo request, providing a username:

GET /projects?private_token=9koXpg98eAheJpvBs5tK&sudo=username
curl --header "Private-Token: 9koXpg98eAheJpvBs5tK" --header "Sudo: username" "https://gitlab.example.com/api/v4/projects"

Example of a valid API call and a request using cURL with sudo request, providing an ID:

GET /projects?private_token=9koXpg98eAheJpvBs5tK&sudo=23
curl --header "Private-Token: 9koXpg98eAheJpvBs5tK" --header "Sudo: 23" "https://gitlab.example.com/api/v4/projects"

Status codes

The API is designed to return different status codes according to context and action. This way, if a request results in an error, the caller is able to get insight into what went wrong.

The following table gives an overview of how the API functions generally behave.

Request type Description
GET Access one or more resources and return the result as JSON.
POST Return 201 Created if the resource is successfully created and return the newly created resource as JSON.
GET / PUT Return 200 OK if the resource is accessed or modified successfully. The (modified) result is returned as JSON.
DELETE Returns 204 No Content if the resuource was deleted successfully.

The following table shows the possible return codes for API requests.

Return values Description
200 OK The GET, PUT or DELETE request was successful, the resource(s) itself is returned as JSON.
204 No Content The server has successfully fulfilled the request and that there is no additional content to send in the response payload body.
201 Created The POST request was successful and the resource is returned as JSON.
304 Not Modified Indicates that the resource has not been modified since the last request.
400 Bad Request A required attribute of the API request is missing, e.g., the title of an issue is not given.
401 Unauthorized The user is not authenticated, a valid user token is necessary.
403 Forbidden The request is not allowed, e.g., the user is not allowed to delete a project.
404 Not Found A resource could not be accessed, e.g., an ID for a resource could not be found.
405 Method Not Allowed The request is not supported.
409 Conflict A conflicting resource already exists, e.g., creating a project with a name that already exists.
412 Indicates the request was denied. May happen if the If-Unmodified-Since header is provided when trying to delete a resource, which was modified in between.
422 Unprocessable The entity could not be processed.
500 Server Error While handling the request something went wrong server-side.

Pagination

Sometimes the returned result will span across many pages. When listing resources you can pass the following parameters:

Parameter Description
page Page number (default: 1)
per_page Number of items to list per page (default: 20, max: 100)

In the example below, we list 50 namespaces per page.

curl --request PUT --header "PRIVATE-TOKEN: 9koXpg98eAheJpvBs5tK" "https://gitlab.example.com/api/v4/namespaces?per_page=50

Pagination Link header

Link headers are sent back with each response. They have rel set to prev/next/first/last and contain the relevant URL. Please use these links instead of generating your own URLs.

In the cURL example below, we limit the output to 3 items per page (per_page=3) and we request the second page (page=2) of comments of the issue with ID 8 which belongs to the project with ID 8:

curl --head --header "PRIVATE-TOKEN: 9koXpg98eAheJpvBs5tK" https://gitlab.example.com/api/v4/projects/8/issues/8/notes?per_page=3&page=2

The response will then be:

HTTP/1.1 200 OK
Cache-Control: no-cache
Content-Length: 1103
Content-Type: application/json
Date: Mon, 18 Jan 2016 09:43:18 GMT
Link: <https://gitlab.example.com/api/v4/projects/8/issues/8/notes?page=1&per_page=3>; rel="prev", <https://gitlab.example.com/api/v4/projects/8/issues/8/notes?page=3&per_page=3>; rel="next", <https://gitlab.example.com/api/v4/projects/8/issues/8/notes?page=1&per_page=3>; rel="first", <https://gitlab.example.com/api/v4/projects/8/issues/8/notes?page=3&per_page=3>; rel="last"
Status: 200 OK
Vary: Origin
X-Next-Page: 3
X-Page: 2
X-Per-Page: 3
X-Prev-Page: 1
X-Request-Id: 732ad4ee-9870-4866-a199-a9db0cde3c86
X-Runtime: 0.108688
X-Total: 8
X-Total-Pages: 3

Other pagination headers

Additional pagination headers are also sent back.

Header Description
X-Total The total number of items
X-Total-Pages The total number of pages
X-Per-Page The number of items per page
X-Page The index of the current page (starting at 1)
X-Next-Page The index of the next page
X-Prev-Page The index of the previous page

Namespaced path encoding

If using namespaced API calls, make sure that the NAMESPACE/PROJECT_NAME is URL-encoded.

For example, / is represented by %2F:

GET /api/v4/projects/diaspora%2Fdiaspora

Branches & tags name encoding

If your branch or tag contains a /, make sure the branch/tag name is URL-encoded.

For example, / is represented by %2F:

GET /api/v4/projects/1/branches/my%2Fbranch/commits

id vs iid

When you work with the API, you may notice two similar fields in API entities: id and iid. The main difference between them is scope.

For example, an issue might have id: 46 and iid: 5.

Parameter Description
id Is unique across all issues and is used for any API call
iid Is unique only in scope of a single project. When you browse issues or merge requests with the Web UI, you see the iid

That means that if you want to get an issue via the API you should use the id:

GET /projects/42/issues/:id

On the other hand, if you want to create a link to a web page you should use the iid:

GET /projects/42/issues/:iid

Data validation and error reporting

When working with the API you may encounter validation errors, in which case the API will answer with an HTTP 400 status.

Such errors appear in two cases:

  • A required attribute of the API request is missing, e.g., the title of an issue is not given
  • An attribute did not pass the validation, e.g., user bio is too long

When an attribute is missing, you will get something like:

HTTP/1.1 400 Bad Request
Content-Type: application/json
{
    "message":"400 (Bad request) \"title\" not given"
}

When a validation error occurs, error messages will be different. They will hold all details of validation errors:

HTTP/1.1 400 Bad Request
Content-Type: application/json
{
    "message": {
        "bio": [
            "is too long (maximum is 255 characters)"
        ]
    }
}

This makes error messages more machine-readable. The format can be described as follows:

{
    "message": {
        "<property-name>": [
            "<error-message>",
            "<error-message>",
            ...
        ],
        "<embed-entity>": {
            "<property-name>": [
                "<error-message>",
                "<error-message>",
                ...
            ],
        }
    }
}

Unknown route

When you try to access an API URL that does not exist you will receive 404 Not Found.

HTTP/1.1 404 Not Found
Content-Type: application/json
{
    "error": "404 Not Found"
}

Encoding + in ISO 8601 dates

If you need to include a + in a query parameter, you may need to use %2B instead due a W3 recommendation that causes a + to be interpreted as a space. For example, in an ISO 8601 date, you may want to pass a time in Mountain Standard Time, such as:

2017-10-17T23:11:13.000+05:30

The correct encoding for the query parameter would be:

2017-10-17T23:11:13.000%2B05:30

Clients

There are many unofficial GitLab API Clients for most of the popular programming languages. Visit the GitLab website for a complete list.

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