Remove feature flag api_always_use_application_json [RUN ALL RSPEC] [RUN AS-IF-FOSS]

changelogs/unreleased/dz-remove-ff-api_always_use_application_json.yml

+---
+title: Remove feature flag api_always_use_application_json
+merge_request: 56777
+author:
+type: removed

config/feature_flags/development/api_always_use_application_json.yml

----
-name: api_always_use_application_json
-introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/42229
-rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/270067
-milestone: '13.6'
-type: development
-group: group::ecosystem
-default_enabled: true

doc/api/README.md

@@ -776,7 +776,3 @@ some API endpoints also support `text/plain`.
 
 In [GitLab 13.10 and later](https://gitlab.com/gitlab-org/gitlab/-/issues/250342),
 API endpoints do not support `text/plain` by default, unless it's explicitly documented.
-
-This change is deployed behind the `:api_always_use_application_json` [feature flag](../user/feature_flags.md),
-enabled by default. On GitLab self-managed instances, GitLab administrators can choose
-to [disable it](../administration/feature_flags.md). **(FREE SELF)**

lib/api/api.rb

@@ -130,32 +130,6 @@ module API
     formatter :json, Gitlab::Json::GrapeFormatter
     content_type :json, 'application/json'
 
-    # Remove the `text/plain+deprecated` with `api_always_use_application_json` feature flag
-    # There is a small chance some users depend on the old behavior.
-    # We this change under a feature flag to see if affects GitLab.com users.
-    # The `+deprecated` is added to distinguish content type
-    # as defined by `API::API` vs ex. `API::Repositories`
-    content_type :txt, 'text/plain+deprecated'
-
-    before do
-      # the feature flag workaround is only for `.txt`
-      api_format = env[Grape::Env::API_FORMAT]
-      next unless api_format == :txt
-
-      # get all defined content-types for the endpoint
-      api_endpoint = env[Grape::Env::API_ENDPOINT]
-      content_types = api_endpoint&.namespace_stackable_with_hash(:content_types).to_h
-
-      # Only overwrite `text/plain+deprecated`
-      if content_types[api_format] == 'text/plain+deprecated'
-        if Feature.enabled?(:api_always_use_application_json, default_enabled: :yaml)
-          content_type 'application/json'
-        else
-          content_type 'text/plain'
-        end
-      end
-    end
-
     # Ensure the namespace is right, otherwise we might load Grape::API::Helpers
     helpers ::API::Helpers
     helpers ::API::Helpers::CommonHelpers

spec/requests/api/api_spec.rb

@@ -170,20 +170,6 @@ RSpec.describe API::API do
         expect(response.media_type).to eq('application/json')
         expect(response.body).to include('{"id":')
       end
-
-      context 'when api_always_use_application_json is disabled' do
-        before do
-          stub_feature_flags(api_always_use_application_json: false)
-        end
-
-        it 'returns text/plain' do
-          subject
-
-          expect(response).to have_gitlab_http_status(:ok)
-          expect(response.media_type).to eq('text/plain')
-          expect(response.body).to include('#<API::Entities::User:')
-        end
-      end
     end
   end
 end