Feature flag API documentation

This commit adds feature flag API documentation

doc/api/feature_flags.md

+# Feature Flags API **(PREMIUM)**
+
+> [Introduced](https://gitlab.com/gitlab-org/gitlab/issues/9566) in [GitLab Premium](https://about.gitlab.com/pricing/) 12.5.
+
+API for accessing resources of [GitLab Feature Flags](../user/project/operations/feature_flags.md).
+
+Users with Developer or higher [permissions](../user/permissions.md) can access Feature Flag API.
+
+## Feature Flags pagination
+
+By default, `GET` requests return 20 results at a time because the API results
+are [paginated](README.md#pagination).
+
+## List feature flags for a project
+
+Gets all feature flags of the requested project.
+
+```
+GET /projects/:id/feature_flags
+```
+
+| Attribute           | Type             | Required   | Description                                                                                                                 |
+| ------------------- | ---------------- | ---------- | --------------------------------------------------------------------------------------------------------------------------- |
+| `id`                | integer/string   | yes        | The ID or [URL-encoded path of the project](README.md#namespaced-path-encoding).                                            |
+| `scope`             | string           | no         | The condition of feature flags, one of: `enabled`, `disabled`.                                                              |
+
+```bash
+curl --header "PRIVATE-TOKEN: <your_access_token>" https://gitlab.example.com/api/v4/projects/1/feature_flags
+```
+
+Example response:
+
+```json
+[
+   {
+      "name":"merge_train",
+      "description":"This feature is about merge train",
+      "created_at":"2019-11-04T08:13:51.423Z",
+      "updated_at":"2019-11-04T08:13:51.423Z",
+      "scopes":[
+         {
+            "id":82,
+            "active":false,
+            "environment_scope":"*",
+            "strategies":[
+               {
+                  "name":"default",
+                  "parameters":{
+
+                  }
+               }
+            ],
+            "created_at":"2019-11-04T08:13:51.425Z",
+            "updated_at":"2019-11-04T08:13:51.425Z"
+         },
+         {
+            "id":83,
+            "active":true,
+            "environment_scope":"review/*",
+            "strategies":[
+               {
+                  "name":"default",
+                  "parameters":{
+
+                  }
+               }
+            ],
+            "created_at":"2019-11-04T08:13:51.427Z",
+            "updated_at":"2019-11-04T08:13:51.427Z"
+         },
+         {
+            "id":84,
+            "active":false,
+            "environment_scope":"production",
+            "strategies":[
+               {
+                  "name":"default",
+                  "parameters":{
+
+                  }
+               }
+            ],
+            "created_at":"2019-11-04T08:13:51.428Z",
+            "updated_at":"2019-11-04T08:13:51.428Z"
+         }
+      ]
+   },
+   {
+      "name":"new_live_trace",
+      "description":"This is a new live trace feature",
+      "created_at":"2019-11-04T08:13:10.507Z",
+      "updated_at":"2019-11-04T08:13:10.507Z",
+      "scopes":[
+         {
+            "id":79,
+            "active":false,
+            "environment_scope":"*",
+            "strategies":[
+               {
+                  "name":"default",
+                  "parameters":{
+
+                  }
+               }
+            ],
+            "created_at":"2019-11-04T08:13:10.516Z",
+            "updated_at":"2019-11-04T08:13:10.516Z"
+         },
+         {
+            "id":80,
+            "active":true,
+            "environment_scope":"staging",
+            "strategies":[
+               {
+                  "name":"default",
+                  "parameters":{
+
+                  }
+               }
+            ],
+            "created_at":"2019-11-04T08:13:10.525Z",
+            "updated_at":"2019-11-04T08:13:10.525Z"
+         },
+         {
+            "id":81,
+            "active":false,
+            "environment_scope":"production",
+            "strategies":[
+               {
+                  "name":"default",
+                  "parameters":{
+
+                  }
+               }
+            ],
+            "created_at":"2019-11-04T08:13:10.527Z",
+            "updated_at":"2019-11-04T08:13:10.527Z"
+         }
+      ]
+   }
+]
+```
+
+## New feature flag
+
+Creates a new feature flag.
+
+```
+POST /projects/:id/feature_flags
+```
+
+| Attribute           | Type             | Required   | Description                                                                            |
+| ------------------- | ---------------- | ---------- | ---------------------------------------------------------------------------------------|
+| `id`                | integer/string   | yes        | The ID or [URL-encoded path of the project](README.md#namespaced-path-encoding).       |
+| `name`              | string           | yes        | The name of the feature flag. |
+| `description`       | string           | no         | The description of the feature flag. |
+| `scopes`            | JSON             | no         | The [feature flag specs](../user/project/operations/feature_flags.md#define-environment-specs) of the feature flag. |
+| `scopes:environment_scope` | string           | no         | The [environment spec](../ci/environments.md#scoping-environments-with-specs). |
+| `scopes:active`            | boolean          | no         | Whether the spec is active. |
+| `scopes:strategies`        | JSON             | no         | The [strategies](../user/project/operations/feature_flags.md#feature-flag-strategies) of the feature flag spec. |
+
+```bash
+curl https://gitlab.example.com/api/v4/projects/1/feature_flags \
+     --header "PRIVATE-TOKEN: <your_access_token>" \
+     --header "Content-type: application/json" \
+     --data @- << EOF
+{
+    "name": "awesome_feature",
+    "scopes": [{ "environment_scope": "*", "active": false, "strategies": [{ "name": "default", "parameters": {} }] },
+               { "environment_scope": "production", "active": true, "strategies": [{ "name": "userWithId", "parameters": { "userIds": "1,2,3" } }] }]
+}
+EOF
+```
+
+Example response:
+
+```json
+{
+   "name":"awesome_feature",
+   "description":null,
+   "created_at":"2019-11-04T08:32:27.288Z",
+   "updated_at":"2019-11-04T08:32:27.288Z",
+   "scopes":[
+      {
+         "id":85,
+         "active":false,
+         "environment_scope":"*",
+         "strategies":[
+            {
+               "name":"default",
+               "parameters":{
+
+               }
+            }
+         ],
+         "created_at":"2019-11-04T08:32:29.324Z",
+         "updated_at":"2019-11-04T08:32:29.324Z"
+      },
+      {
+         "id":86,
+         "active":true,
+         "environment_scope":"production",
+         "strategies":[
+            {
+               "name":"userWithId",
+               "parameters":{
+                  "userIds":"1,2,3"
+               }
+            }
+         ],
+         "created_at":"2019-11-04T08:32:29.328Z",
+         "updated_at":"2019-11-04T08:32:29.328Z"
+      }
+   ]
+}
+```
+
+## Single feature flag
+
+Gets a single feature flag.
+
+```
+GET /projects/:id/feature_flags/:name
+```
+
+| Attribute           | Type             | Required   | Description                                                                            |
+| ------------------- | ---------------- | ---------- | ---------------------------------------------------------------------------------------|
+| `id`                | integer/string   | yes        | The ID or [URL-encoded path of the project](README.md#namespaced-path-encoding).       |
+| `name`              | string           | yes        | The name of the feature flag.  |
+
+```bash
+curl --header "PRIVATE-TOKEN: <your_access_token>" https://gitlab.example.com/api/v4/projects/1/feature_flags/new_live_trace
+```
+
+Example response:
+
+```json
+{
+   "name":"new_live_trace",
+   "description":"This is a new live trace feature",
+   "created_at":"2019-11-04T08:13:10.507Z",
+   "updated_at":"2019-11-04T08:13:10.507Z",
+   "scopes":[
+      {
+         "id":79,
+         "active":false,
+         "environment_scope":"*",
+         "strategies":[
+            {
+               "name":"default",
+               "parameters":{
+
+               }
+            }
+         ],
+         "created_at":"2019-11-04T08:13:10.516Z",
+         "updated_at":"2019-11-04T08:13:10.516Z"
+      },
+      {
+         "id":80,
+         "active":true,
+         "environment_scope":"staging",
+         "strategies":[
+            {
+               "name":"default",
+               "parameters":{
+
+               }
+            }
+         ],
+         "created_at":"2019-11-04T08:13:10.525Z",
+         "updated_at":"2019-11-04T08:13:10.525Z"
+      },
+      {
+         "id":81,
+         "active":false,
+         "environment_scope":"production",
+         "strategies":[
+            {
+               "name":"default",
+               "parameters":{
+
+               }
+            }
+         ],
+         "created_at":"2019-11-04T08:13:10.527Z",
+         "updated_at":"2019-11-04T08:13:10.527Z"
+      }
+   ]
+}
+```
+
+## Delete feature flag
+
+Deletes a feature flag.
+
+```
+DELETE /projects/:id/feature_flags/:name
+```
+
+| Attribute           | Type             | Required   | Description                                                                            |
+| ------------------- | ---------------- | ---------- | ---------------------------------------------------------------------------------------|
+| `id`                | integer/string   | yes        | The ID or [URL-encoded path of the project](README.md#namespaced-path-encoding).       |
+| `name`              | string           | yes        | The name of the feature flag.  |
+
+```bash
+curl --header "PRIVATE-TOKEN: <your_access_token>" --request DELETE https://gitlab.example.com/api/v4/projects/1/feature_flags/awesome_feature
+```

doc/user/permissions.md

@@ -103,6 +103,7 @@ The following table depicts the various user permission levels in a project.
 | Apply code change suggestions                     |         |            | ✓           | ✓        | ✓      |
 | Create and edit wiki pages                        |         |            | ✓           | ✓        | ✓      |
 | Rewrite/remove Git tags                           |         |            | ✓           | ✓        | ✓      |
+| Manage Feature Flags **(PREMIUM)**                |         |            | ✓           | ✓        | ✓      |
 | Use environment terminals                         |         |            |             | ✓        | ✓      |
 | Run Web IDE's Interactive Web Terminals **(ULTIMATE ONLY)** |     |      |             | ✓        | ✓      |
 | Add new team members                              |         |            |             | ✓        | ✓      |

doc/user/project/operations/feature_flags.md

@@ -81,7 +81,14 @@ NOTE: **NOTE**
 We'd highly recommend you to use the [Environment](../../../ci/environments.md)
 feature in order to quickly assess which flag is enabled per environment.
 
-## Rollout strategy
+## Feature Flag strategies
+
+GitLab Feature Flag adopts [Unleash](https://unleash.github.io)
+as the feature flag engine. In unleash, there is a concept of rulesets for granular feature flag controls,
+called [strategies](https://unleash.github.io/docs/activation_strategy).
+Supported strategies for GitLab Feature Flags are described below.
+
+### Rollout strategy
 
 > [Introduced](https://gitlab.com/gitlab-org/gitlab/issues/8240) in GitLab 12.2.
 
@@ -91,13 +98,13 @@ The status of an environment spec ultimately determines whether or not a feature
 For instance, a feature will always be disabled for every user if the matching environment spec has a disabled status, regardless of the chosen rollout strategy.
 However, a feature will be enabled for 50% of logged-in users if the matching environment spec has an enabled status along with a **Percent rollout (logged in users)** strategy set to 50%.
 
-### All users
+#### All users
 
 Enables the feature for all users. It is implemented using the Unleash
 [`default`](https://unleash.github.io/docs/activation_strategy#default)
 activation strategy.
 
-### Percent rollout (logged in users)
+#### Percent rollout (logged in users)
 
 Enables the feature for a percentage of authenticated users. It is
 implemented using the Unleash
@@ -112,7 +119,7 @@ CAUTION: **Caution:**
 If this strategy is selected, then the Unleash client **must** be given a user
 ID for the feature to be enabled. See the [Ruby example](#ruby-application-example) below.
 
-## Target users
+### Target users strategy
 
 > [Introduced](https://gitlab.com/gitlab-org/gitlab/issues/8240) in GitLab 12.2.
 
@@ -134,7 +141,7 @@ In order to use Feature Flags, you need to first
 [get the access credentials](#configuring-feature-flags) from GitLab and then
 prepare your application and hook it with a [client library](#client-libraries).
 
-### Configuring Feature Flags
+## Configuring Feature Flags
 
 To get the access credentials that your application will need to talk to GitLab:
 
@@ -153,7 +160,7 @@ if **Instance ID** will be single token or multiple tokens, assigned to the
 **Environment**. Also, **Application name** could describe the version of
 application instead of the running environment.
 
-### Client libraries
+## Client libraries
 
 GitLab currently implements a single backend that is compatible with
 [Unleash](https://github.com/Unleash/unleash#client-implementations) clients.
@@ -178,7 +185,7 @@ Community contributed clients:
 - [Unofficial .Net Core Unleash client](https://github.com/onybo/unleash-client-core)
 - [Unleash client for Python 3](https://github.com/aes/unleash-client-python)
 
-### Golang application example
+## Golang application example
 
 Here's an example of how to integrate the feature flags in a Golang application:
 
@@ -219,7 +226,7 @@ func main() {
 }
 ```
 
-### Ruby application example
+## Ruby application example
 
 Here's an example of how to integrate the feature flags in a Ruby application.
 
@@ -249,3 +256,11 @@ else
   puts "hello, world!"
 end
 ```
+
+## Feature Flags API
+
+You can create, update, read, and delete Feature Flags via API
+to control them in an automated flow:
+
+- [Feature Flags API](../../../api/feature_flags.md)
+- [Feature Flag Specs API](../../../api/feature_flag_specs.md)

ee/changelogs/unreleased/feature-flag-documentation.yml

+---
+title: Add public API for Feature Flags
+merge_request: 19547
+author:
+type: added

ee/lib/api/feature_flag_scopes.rb

@@ -4,11 +4,10 @@ module API
   class FeatureFlagScopes < Grape::API
     include PaginationParams
 
-    ENVIRONMENT_SCOPE_ENDPOINT_REQUIREMETS = FeatureFlags::FEATURE_FLAG_ENDPOINT_REQUIREMENTS
+    ENVIRONMENT_SCOPE_ENDPOINT_REQUIREMENTS = FeatureFlags::FEATURE_FLAG_ENDPOINT_REQUIREMENTS
       .merge(environment_scope: API::NO_SLASH_URL_PART_REGEX)
 
     before do
-      not_found! unless Feature.enabled?(:feature_flag_api, user_project)
       authorize_read_feature_flags!
     end
 
@@ -18,7 +17,7 @@ module API
     resource 'projects/:id', requirements: API::NAMESPACE_OR_PROJECT_REQUIREMENTS do
       resource :feature_flag_scopes do
         desc 'Get all effective feature flags under the environment' do
-          detail 'This feature is going to be introduced in GitLab 12.5 if `feature_flag_api` feature flag is removed'
+          detail 'This feature was introduced in GitLab 12.5'
           success EE::API::Entities::FeatureFlag::DetailedScope
         end
         params do
@@ -35,7 +34,7 @@ module API
       resource 'feature_flags/:name', requirements: FeatureFlags::FEATURE_FLAG_ENDPOINT_REQUIREMENTS do
         resource :scopes do
           desc 'Get all scopes of a feature flag' do
-            detail 'This feature is going to be introduced in GitLab 12.5 if `feature_flag_api` feature flag is removed'
+            detail 'This feature was introduced in GitLab 12.5'
             success EE::API::Entities::FeatureFlag::Scope
           end
           params do
@@ -46,12 +45,12 @@ module API
           end
 
           desc 'Create a scope of a feature flag' do
-            detail 'This feature is going to be introduced in GitLab 12.5 if `feature_flag_api` feature flag is removed'
+            detail 'This feature was introduced in GitLab 12.5'
             success EE::API::Entities::FeatureFlag::Scope
           end
           params do
             requires :environment_scope, type: String, desc: 'The environment scope of the scope'
-            requires :active, type: Boolean, desc: 'Active/inactive of the scope'
+            requires :active, type: Boolean, desc: 'Whether the scope is active'
             requires :strategies, type: JSON, desc: 'The strategies of the scope'
           end
           post do
@@ -71,9 +70,9 @@ module API
           params do
             requires :environment_scope, type: String, desc: 'URL-encoded environment scope'
           end
-          resource ':environment_scope', requirements: ENVIRONMENT_SCOPE_ENDPOINT_REQUIREMETS do
+          resource ':environment_scope', requirements: ENVIRONMENT_SCOPE_ENDPOINT_REQUIREMENTS do
             desc 'Get a scope of a feature flag' do
-              detail 'This feature is going to be introduced in GitLab 12.5 if `feature_flag_api` feature flag is removed'
+              detail 'This feature was introduced in GitLab 12.5'
               success EE::API::Entities::FeatureFlag::Scope
             end
             get do
@@ -81,11 +80,11 @@ module API
             end
 
             desc 'Update a scope of a feature flag' do
-              detail 'This feature is going to be introduced in GitLab 12.5 if `feature_flag_api` feature flag is removed'
+              detail 'This feature was introduced in GitLab 12.5'
               success EE::API::Entities::FeatureFlag::Scope
             end
             params do
-              optional :active, type: Boolean, desc: 'Active/inactive of the scope'
+              optional :active, type: Boolean, desc: 'Whether the scope is active'
               optional :strategies, type: JSON, desc: 'The strategies of the scope'
             end
             put do
@@ -108,7 +107,7 @@ module API
             end
 
             desc 'Delete a scope from a feature flag' do
-              detail 'This feature is going to be introduced in GitLab 12.5 if `feature_flag_api` feature flag is removed'
+              detail 'This feature was introduced in GitLab 12.5'
               success EE::API::Entities::FeatureFlag::Scope
             end
             delete do

ee/lib/api/feature_flags.rb

@@ -8,7 +8,6 @@ module API
         .merge(name: API::NO_SLASH_URL_PART_REGEX)
 
     before do
-      not_found! unless Feature.enabled?(:feature_flag_api, user_project)
       authorize_read_feature_flags!
     end
 
@@ -18,7 +17,7 @@ module API
     resource 'projects/:id', requirements: API::NAMESPACE_OR_PROJECT_REQUIREMENTS do
       resource :feature_flags do
         desc 'Get all feature flags of a project' do
-          detail 'This feature is going to be introduced in GitLab 12.5 if `feature_flag_api` feature flag is removed'
+          detail 'This feature was introduced in GitLab 12.5'
           success EE::API::Entities::FeatureFlag
         end
         params do
@@ -35,7 +34,7 @@ module API
         end
 
         desc 'Create a new feature flag' do
-          detail 'This feature is going to be introduced in GitLab 12.5 if `feature_flag_api` feature flag is removed'
+          detail 'This feature was introduced in GitLab 12.5'
           success EE::API::Entities::FeatureFlag
         end
         params do
@@ -70,7 +69,7 @@ module API
       end
       resource 'feature_flags/:name', requirements: FEATURE_FLAG_ENDPOINT_REQUIREMENTS do
         desc 'Get a feature flag of a project' do
-          detail 'This feature is going to be introduced in GitLab 12.5 if `feature_flag_api` feature flag is removed'
+          detail 'This feature was introduced in GitLab 12.5'
           success EE::API::Entities::FeatureFlag
         end
         get do
@@ -80,7 +79,7 @@ module API
         end
 
         desc 'Enable a strategy for a feature flag on an environment' do
-          detail 'This feature is going to be introduced in GitLab 12.5 if `feature_flag_api` feature flag is removed'
+          detail 'This feature was introduced in GitLab 12.5'
           success EE::API::Entities::FeatureFlag
         end
         params do
@@ -88,6 +87,8 @@ module API
           requires :strategy,          type: JSON,   desc: 'The strategy to be enabled on the scope'
         end
         post :enable do
+          not_found! unless Feature.enabled?(:feature_flag_api, user_project)
+
           result = ::FeatureFlags::EnableService
             .new(user_project, current_user, params).execute
 
@@ -108,6 +109,8 @@ module API
           requires :strategy,          type: JSON,   desc: 'The strategy to be disabled on the scope'
         end
         post :disable do
+          not_found! unless Feature.enabled?(:feature_flag_api, user_project)
+
           result = ::FeatureFlags::DisableService
             .new(user_project, current_user, params).execute
 
@@ -120,7 +123,7 @@ module API
         end
 
         desc 'Delete a feature flag' do
-          detail 'This feature is going to be introduced in GitLab 12.5 if `feature_flag_api` feature flag is removed'
+          detail 'This feature was introduced in GitLab 12.5'
           success EE::API::Entities::FeatureFlag
         end
         delete do

ee/spec/requests/api/feature_flag_scopes_spec.rb

@@ -38,18 +38,6 @@ describe API::FeatureFlagScopes do
         expect(response).to have_gitlab_http_status(:forbidden)
       end
     end
-
-    context 'when feature_flag_api feature flag is disabled' do
-      before do
-        stub_feature_flags(feature_flag_api: false)
-      end
-
-      it 'forbids the request' do
-        subject
-
-        expect(response).to have_gitlab_http_status(:not_found)
-      end
-    end
   end
 
   shared_examples_for 'not found' do