Add remote mirrors API documentation

changelogs/unreleased/rs-remote-mirrors-docs.yml

+---
+title: Add remote mirrors API
+merge_request:
+author:
+type: added

doc/api/api_resources.md

@@ -61,6 +61,7 @@ The following API resources are available in the project context:
 | [Protected tags](protected_tags.md)                                 | `/projects/:id/protected_tags`                                                                                                                                                                        |
 | [Releases](releases/index.md)                                       | `/projects/:id/releases`                                                                                                                                                                              |
 | [Release links](releases/links.md)                                  | `/projects/:id/releases/.../assets/links`                                                                                                                                                             |
+| [Remote mirrors](remote_mirrors.md)                                 | `/projects/:id/remote_mirrors`                                                                                                                                                                        |
 | [Repositories](repositories.md)                                     | `/projects/:id/repository`                                                                                                                                                                            |
 | [Repository files](repository_files.md)                             | `/projects/:id/repository/files`                                                                                                                                                                      |
 | [Repository submodules](repository_submodules.md)                   | `/projects/:id/repository/submodules`                                                                                                                                                                 |

doc/api/remote_mirrors.md

+# Project remote mirrors API
+
+[Push mirrors](../user/project/repository/repository_mirroring.md#pushing-to-a-remote-repository-core)
+defined on a project's repository settings are called "remote mirrors", and the
+state of these mirrors can be queried and modified via the remote mirror API
+outlined below.
+
+## List a project's remote mirrors
+
+> [Introduced](https://gitlab.com/gitlab-org/gitlab/issues/38121) in GitLab 12.9.
+
+Returns an Array of remote mirrors and their statuses:
+
+```text
+GET /projects/:id/remote_mirrors
+```
+
+Example request:
+
+```sh
+curl --header "PRIVATE-TOKEN: <your_access_token>" 'https://gitlab.example.com/api/v4/projects/42/remote_mirrors'
+```
+
+Example response:
+
+```json
+[
+  {
+    "enabled": true,
+    "id": 101486,
+    "last_error": null,
+    "last_successful_update_at": "2020-01-06T17:32:02.823Z",
+    "last_update_at": "2020-01-06T17:32:02.823Z",
+    "last_update_started_at": "2020-01-06T17:31:55.864Z",
+    "only_protected_branches": true,
+    "update_status": "finished",
+    "url": "https://*****:*****@gitlab.com/gitlab-org/security/gitlab.git"
+  }
+]
+```
+
+NOTE: **Note:**
+For security reasons, the `url` attribute will always be scrubbed of username
+and password information.
+
+## Update a remote mirror's attributes
+
+> [Introduced](https://gitlab.com/gitlab-org/gitlab/issues/38121) in GitLab 12.9.
+
+Toggle a remote mirror on or off, or change which types of branches are
+mirrored:
+
+```text
+PUT /projects/:id/remote_mirrors/:mirror_id
+```
+
+| Attribute                 | Type    | Required   | Description                                         |
+| :----------               | :-----  | :--------- | :------------                                       |
+| `mirror_id`               | Integer | yes        | The remote mirror ID.                               |
+| `enabled`                 | Boolean | no         | Determines if the mirror is enabled.                |
+| `only_protected_branches` | Boolean | no         | Determines if only protected branches are mirrored. |
+
+Example request:
+
+```sh
+curl --request PUT --data "enabled=false" --header "PRIVATE-TOKEN: <your_access_token>" 'https://gitlab.example.com/api/v4/projects/42/remote_mirrors/101486'
+```
+
+Example response:
+
+```json
+{
+    "enabled": false,
+    "id": 101486,
+    "last_error": null,
+    "last_successful_update_at": "2020-01-06T17:32:02.823Z",
+    "last_update_at": "2020-01-06T17:32:02.823Z",
+    "last_update_started_at": "2020-01-06T17:31:55.864Z",
+    "only_protected_branches": true,
+    "update_status": "finished",
+    "url": "https://*****:*****@gitlab.com/gitlab-org/security/gitlab.git"
+}
+```

doc/user/project/repository/repository_mirroring.md

@@ -69,6 +69,11 @@ Changes pushed to files in the repository are automatically pushed to the remote
 In the case of a diverged branch, you will see an error indicated at the **Mirroring repositories**
 section.
 
+### Configuring push mirrors through the API
+
+You can also create and modify project push mirrors through the
+[remote mirrors API](../../../api/remote_mirrors.md).
+
 ### Push only protected branches **(CORE)**
 
 > - [Introduced](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/3350) in [GitLab Starter](https://about.gitlab.com/pricing/) 10.3.