Merge branch 'zj-pipelines-api-endpoints' into 'master'

Add endpoints for pipelines

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- [x] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- [x] API support added
- Tests
  - [x] Added for this feature/bug
  - [x] All builds are passing
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [ ] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [ ] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

See merge request !5837

2 files changed, 208 insertions, 0 deletions

diff --git a/doc/api/README.md b/doc/api/README.md
index f3117815c7c..3e79cce0120 100644
--- a/doc/api/README.md
+++ b/doc/api/README.md
@@ -26,6 +26,7 @@ following locations:
 - [Open source license templates](licenses.md)
 - [Namespaces](namespaces.md)
 - [Notes](notes.md) (comments)
+- [Pipelines](pipelines.md)
 - [Projects](projects.md) including setting Webhooks
 - [Project Access Requests](access_requests.md)
 - [Project Members](members.md)
diff --git a/doc/api/pipelines.md b/doc/api/pipelines.md
new file mode 100644
index 00000000000..847408a7f61
--- /dev/null
+++ b/doc/api/pipelines.md
@@ -0,0 +1,207 @@
+# Pipelines API
+
+## List project pipelines
+
+> [Introduced][ce-5837] in GitLab 8.11
+
+```
+GET /projects/:id/pipelines
+```
+
+| Attribute | Type    | Required | Description         |
+|-----------|---------|----------|---------------------|
+| `id`      | integer | yes      | The ID of a project |
+
+```
+curl --header "PRIVATE-TOKEN: 9koXpg98eAheJpvBs5tK" "https://gitlab.example.com/api/v3/projects/1/pipelines"
+```
+
+Example of response
+
+```json
+[
+  {
+    "id": 47,
+    "status": "pending",
+    "ref": "new-pipeline",
+    "sha": "a91957a858320c0e17f3a0eca7cfacbff50ea29a",
+    "before_sha": "a91957a858320c0e17f3a0eca7cfacbff50ea29a",
+    "tag": false,
+    "yaml_errors": null,
+    "user": {
+      "name": "Administrator",
+      "username": "root",
+      "id": 1,
+      "state": "active",
+      "avatar_url": "http://www.gravatar.com/avatar/e64c7d89f26bd1972efa854d13d7dd61?s=80&d=identicon",
+      "web_url": "http://localhost:3000/u/root"
+    },
+    "created_at": "2016-08-16T10:23:19.007Z",
+    "updated_at": "2016-08-16T10:23:19.216Z",
+    "started_at": null,
+    "finished_at": null,
+    "committed_at": null,
+    "duration": null
+  },
+  {
+    "id": 48,
+    "status": "pending",
+    "ref": "new-pipeline",
+    "sha": "eb94b618fb5865b26e80fdd8ae531b7a63ad851a",
+    "before_sha": "eb94b618fb5865b26e80fdd8ae531b7a63ad851a",
+    "tag": false,
+    "yaml_errors": null,
+    "user": {
+      "name": "Administrator",
+      "username": "root",
+      "id": 1,
+      "state": "active",
+      "avatar_url": "http://www.gravatar.com/avatar/e64c7d89f26bd1972efa854d13d7dd61?s=80&d=identicon",
+      "web_url": "http://localhost:3000/u/root"
+    },
+    "created_at": "2016-08-16T10:23:21.184Z",
+    "updated_at": "2016-08-16T10:23:21.314Z",
+    "started_at": null,
+    "finished_at": null,
+    "committed_at": null,
+    "duration": null
+  }
+]
+```
+
+## Get a single pipeline
+
+> [Introduced][ce-5837] in GitLab 8.11
+
+```
+GET /projects/:id/pipelines/:pipeline_id
+```
+
+| Attribute  | Type    | Required | Description         |
+|------------|---------|----------|---------------------|
+| `id`       | integer | yes      | The ID of a project |
+| `pipeline_id` | integer | yes      | The ID of a pipeline   |
+
+```
+curl --header "PRIVATE-TOKEN: 9koXpg98eAheJpvBs5tK" "https://gitlab.example.com/api/v3/projects/1/pipeline/46"
+```
+
+Example of response
+
+```json
+{
+  "id": 46,
+  "status": "success",
+  "ref": "master",
+  "sha": "a91957a858320c0e17f3a0eca7cfacbff50ea29a",
+  "before_sha": "a91957a858320c0e17f3a0eca7cfacbff50ea29a",
+  "tag": false,
+  "yaml_errors": null,
+  "user": {
+    "name": "Administrator",
+    "username": "root",
+    "id": 1,
+    "state": "active",
+    "avatar_url": "http://www.gravatar.com/avatar/e64c7d89f26bd1972efa854d13d7dd61?s=80&d=identicon",
+    "web_url": "http://localhost:3000/u/root"
+  },
+  "created_at": "2016-08-11T11:28:34.085Z",
+  "updated_at": "2016-08-11T11:32:35.169Z",
+  "started_at": null,
+  "finished_at": "2016-08-11T11:32:35.145Z",
+  "committed_at": null,
+  "duration": null
+}
+```
+
+## Retry failed builds in a pipeline
+
+> [Introduced][ce-5837] in GitLab 8.11
+
+```
+POST /projects/:id/pipelines/:pipeline_id/retry
+```
+
+| Attribute  | Type    | Required | Description         |
+|------------|---------|----------|---------------------|
+| `id`       | integer | yes      | The ID of a project |
+| `pipeline_id` | integer | yes   | The ID of a pipeline |
+
+```
+curl --header "PRIVATE-TOKEN: 9koXpg98eAheJpvBs5tK" "https://gitlab.example.com/api/v3/projects/1/pipelines/46/retry"
+```
+
+Response:
+
+```json
+{
+  "id": 46,
+  "status": "pending",
+  "ref": "master",
+  "sha": "a91957a858320c0e17f3a0eca7cfacbff50ea29a",
+  "before_sha": "a91957a858320c0e17f3a0eca7cfacbff50ea29a",
+  "tag": false,
+  "yaml_errors": null,
+  "user": {
+    "name": "Administrator",
+    "username": "root",
+    "id": 1,
+    "state": "active",
+    "avatar_url": "http://www.gravatar.com/avatar/e64c7d89f26bd1972efa854d13d7dd61?s=80&d=identicon",
+    "web_url": "http://localhost:3000/u/root"
+  },
+  "created_at": "2016-08-11T11:28:34.085Z",
+  "updated_at": "2016-08-11T11:32:35.169Z",
+  "started_at": null,
+  "finished_at": "2016-08-11T11:32:35.145Z",
+  "committed_at": null,
+  "duration": null
+}
+```
+
+## Cancel a pipelines builds
+
+> [Introduced][ce-5837] in GitLab 8.11
+
+```
+POST /projects/:id/pipelines/:pipeline_id/cancel
+```
+
+| Attribute  | Type    | Required | Description         |
+|------------|---------|----------|---------------------|
+| `id`       | integer | yes      | The ID of a project |
+| `pipeline_id` | integer | yes   | The ID of a pipeline |
+
+```
+curl --header "PRIVATE-TOKEN: 9koXpg98eAheJpvBs5tK" "https://gitlab.example.com/api/v3/projects/1/pipelines/46/cancel"
+```
+
+Response:
+
+```json
+{
+  "id": 46,
+  "status": "canceled",
+  "ref": "master",
+  "sha": "a91957a858320c0e17f3a0eca7cfacbff50ea29a",
+  "before_sha": "a91957a858320c0e17f3a0eca7cfacbff50ea29a",
+  "tag": false,
+  "yaml_errors": null,
+  "user": {
+    "name": "Administrator",
+    "username": "root",
+    "id": 1,
+    "state": "active",
+    "avatar_url": "http://www.gravatar.com/avatar/e64c7d89f26bd1972efa854d13d7dd61?s=80&d=identicon",
+    "web_url": "http://localhost:3000/u/root"
+  },
+  "created_at": "2016-08-11T11:28:34.085Z",
+  "updated_at": "2016-08-11T11:32:35.169Z",
+  "started_at": null,
+  "finished_at": "2016-08-11T11:32:35.145Z",
+  "committed_at": null,
+  "duration": null
+}
+```
+
+[ce-5837]: https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/5837