Merge branch '58375-api-controller' into 'master'

Add a prometheus proxy API per environment

Closes #58375

See merge request gitlab-org/gitlab-ce!26841

7 files changed, 204 insertions, 0 deletions

diff --git a/app/controllers/projects/environments/prometheus_api_controller.rb b/app/controllers/projects/environments/prometheus_api_controller.rb
new file mode 100644
index 00000000000..fd3320637b0
--- /dev/null
+++ b/app/controllers/projects/environments/prometheus_api_controller.rb
@@ -0,0 +1,37 @@
+# frozen_string_literal: true
+
+class Projects::Environments::PrometheusApiController < Projects::ApplicationController
+  before_action :authorize_read_prometheus!
+  before_action :environment
+
+  def proxy
+    result = Prometheus::ProxyService.new(
+      environment,
+      request.method,
+      params[:proxy_path],
+      params.permit!
+    ).execute
+
+    if result.nil?
+      return render status: :accepted, json: {
+        status: _('processing'),
+        message: _('Not ready yet. Try again later.')
+      }
+    end
+
+    if result[:status] == :success
+      render status: result[:http_status], json: result[:body]
+    else
+      render(
+        status: result[:http_status] || :bad_request,
+        json: { status: result[:status], message: result[:message] }
+      )
+    end
+  end
+
+  private
+
+  def environment
+    @environment ||= project.environments.find(params[:id])
+  end
+end
diff --git a/app/policies/project_policy.rb b/app/policies/project_policy.rb
index 75825c8fac0..26d7d6e84c4 100644
--- a/app/policies/project_policy.rb
+++ b/app/policies/project_policy.rb
@@ -204,6 +204,7 @@ class ProjectPolicy < BasePolicy
     enable :read_merge_request
     enable :read_sentry_issue
     enable :read_release
+    enable :read_prometheus
   end
 
   # We define `:public_user_access` separately because there are cases in gitlab-ee
diff --git a/changelogs/unreleased/58375-api-controller.yml b/changelogs/unreleased/58375-api-controller.yml
new file mode 100644
index 00000000000..60f21b37ae7
--- /dev/null
+++ b/changelogs/unreleased/58375-api-controller.yml
@@ -0,0 +1,5 @@
+---
+title: Add a Prometheus API per environment
+merge_request: 26841
+author:
+type: added
diff --git a/config/routes/project.rb b/config/routes/project.rb
index d60a5cc9ae8..1cb8f331f6f 100644
--- a/config/routes/project.rb
+++ b/config/routes/project.rb
@@ -219,6 +219,8 @@ constraints(::Constraints::ProjectUrlConstrainer.new) do
           get :metrics
           get :additional_metrics
           get '/terminal.ws/authorize', to: 'environments#terminal_websocket_authorize', constraints: { format: nil }
+
+          get '/prometheus/api/v1/*proxy_path', to: 'environments/prometheus_api#proxy'
         end
 
         collection do
diff --git a/locale/gitlab.pot b/locale/gitlab.pot
index a0168dec980..ea08f468616 100644
--- a/locale/gitlab.pot
+++ b/locale/gitlab.pot
@@ -5492,6 +5492,9 @@ msgstr ""
 msgid "Not now"
 msgstr ""
 
+msgid "Not ready yet. Try again later."
+msgstr ""
+
 msgid "Not started"
 msgstr ""
 
@@ -10049,6 +10052,9 @@ msgstr ""
 msgid "private"
 msgstr ""
 
+msgid "processing"
+msgstr ""
+
 msgid "project"
 msgstr ""
 
diff --git a/spec/controllers/projects/environments/prometheus_api_controller_spec.rb b/spec/controllers/projects/environments/prometheus_api_controller_spec.rb
new file mode 100644
index 00000000000..5a0b92c2514
--- /dev/null
+++ b/spec/controllers/projects/environments/prometheus_api_controller_spec.rb
@@ -0,0 +1,152 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe Projects::Environments::PrometheusApiController do
+  set(:project) { create(:project) }
+  set(:environment) { create(:environment, project: project) }
+  set(:user) { create(:user) }
+
+  before do
+    project.add_reporter(user)
+    sign_in(user)
+  end
+
+  describe 'GET #proxy' do
+    let(:prometheus_proxy_service) { instance_double(Prometheus::ProxyService) }
+    let(:expected_params) do
+      ActionController::Parameters.new(
+        environment_params(
+          proxy_path: 'query',
+          controller: 'projects/environments/prometheus_api',
+          action: 'proxy'
+        )
+      ).permit!
+    end
+
+    context 'with valid requests' do
+      before do
+        allow(Prometheus::ProxyService).to receive(:new)
+          .with(environment, 'GET', 'query', expected_params)
+          .and_return(prometheus_proxy_service)
+
+        allow(prometheus_proxy_service).to receive(:execute)
+          .and_return(service_result)
+      end
+
+      context 'with success result' do
+        let(:service_result) { { status: :success, body: prometheus_body } }
+        let(:prometheus_body) { '{"status":"success"}' }
+        let(:prometheus_json_body) { JSON.parse(prometheus_body) }
+
+        it 'returns prometheus response' do
+          get :proxy, params: environment_params
+
+          expect(Prometheus::ProxyService).to have_received(:new)
+            .with(environment, 'GET', 'query', expected_params)
+          expect(response).to have_gitlab_http_status(:ok)
+          expect(json_response).to eq(prometheus_json_body)
+        end
+      end
+
+      context 'with nil result' do
+        let(:service_result) { nil }
+
+        it 'returns 202 accepted' do
+          get :proxy, params: environment_params
+
+          expect(json_response['status']).to eq('processing')
+          expect(json_response['message']).to eq('Not ready yet. Try again later.')
+          expect(response).to have_gitlab_http_status(:accepted)
+        end
+      end
+
+      context 'with 404 result' do
+        let(:service_result) { { http_status: 404, status: :success, body: '{"body": "value"}' } }
+
+        it 'returns body' do
+          get :proxy, params: environment_params
+
+          expect(response).to have_gitlab_http_status(:not_found)
+          expect(json_response['body']).to eq('value')
+        end
+      end
+
+      context 'with error result' do
+        context 'with http_status' do
+          let(:service_result) do
+            { http_status: :service_unavailable, status: :error, message: 'error message' }
+          end
+
+          it 'sets the http response status code' do
+            get :proxy, params: environment_params
+
+            expect(response).to have_gitlab_http_status(:service_unavailable)
+            expect(json_response['status']).to eq('error')
+            expect(json_response['message']).to eq('error message')
+          end
+        end
+
+        context 'without http_status' do
+          let(:service_result) { { status: :error, message: 'error message' } }
+
+          it 'returns bad_request' do
+            get :proxy, params: environment_params
+
+            expect(response).to have_gitlab_http_status(:bad_request)
+            expect(json_response['status']).to eq('error')
+            expect(json_response['message']).to eq('error message')
+          end
+        end
+      end
+    end
+
+    context 'with inappropriate requests' do
+      context 'with anonymous user' do
+        before do
+          sign_out(user)
+        end
+
+        it 'redirects to signin page' do
+          get :proxy, params: environment_params
+
+          expect(response).to redirect_to(new_user_session_path)
+        end
+      end
+
+      context 'without correct permissions' do
+        before do
+          project.team.truncate
+        end
+
+        it 'returns 404' do
+          get :proxy, params: environment_params
+
+          expect(response).to have_gitlab_http_status(:not_found)
+        end
+      end
+    end
+
+    context 'with invalid environment id' do
+      let(:other_environment) { create(:environment) }
+
+      it 'returns 404' do
+        get :proxy, params: environment_params(id: other_environment.id)
+
+        expect(response).to have_gitlab_http_status(:not_found)
+      end
+    end
+  end
+
+  private
+
+  def environment_params(params = {})
+    {
+      id: environment.id.to_s,
+      namespace_id: project.namespace.name,
+      project_id: project.name,
+      proxy_path: 'query',
+      query: '1'
+    }.merge(params)
+  end
+end
diff --git a/spec/support/shared_context/policies/project_policy_shared_context.rb b/spec/support/shared_context/policies/project_policy_shared_context.rb
index 3ad6e067674..ee5cfcd850d 100644
--- a/spec/support/shared_context/policies/project_policy_shared_context.rb
+++ b/spec/support/shared_context/policies/project_policy_shared_context.rb
@@ -25,6 +25,7 @@ RSpec.shared_context 'ProjectPolicy context' do
       admin_issue admin_label admin_list read_commit_status read_build
       read_container_image read_pipeline read_environment read_deployment
       read_merge_request download_wiki_code read_sentry_issue read_release
+      read_prometheus
     ]
   end