Merge branch 'enable-polling-env' into 'master'

Re-enable polling for environments

See merge request !12678

app/controllers/projects/environments_controller.rb

@@ -15,6 +15,8 @@ class Projects::EnvironmentsController < Projects::ApplicationController
     respond_to do |format|
       format.html
       format.json do
+        Gitlab::PollingInterval.set_header(response, interval: 3_000)
+
         render json: {
           environments: EnvironmentSerializer
             .new(project: @project, current_user: @current_user)

changelogs/unreleased/enable-polling-env.yml

+---
+title: Re-enable realtime for environments table
+merge_request:
+author:

spec/controllers/projects/environments_controller_spec.rb

@@ -58,11 +58,9 @@ describe Projects::EnvironmentsController do
           expect(json_response['stopped_count']).to eq 1
         end
 
-        it 'does not set the polling interval header' do
-          # TODO, this is a temporary fix, see follow up issue:
-          # https://gitlab.com/gitlab-org/gitlab-ee/issues/2677
+        it 'sets the polling interval header' do
           expect(response).to have_http_status(:ok)
-          expect(response.headers['Poll-Interval']).to be_nil
+          expect(response.headers['Poll-Interval']).to eq("3000")
         end
       end