Convert RestClient to Gitlab::HTTP for Prometheus Monitor

- Closes #60024

- Change PrometheusClient.new to accept a base url instead of an
  already created RestClient

- Use Gitlab::HTTP in PrometheusClient instead of creating RestClient
  in PrometheusService

- Move http_options from PrometheusService to
  PrometheusClient (follow_redirects: false)

- ensure that base urls don't have the trailing slash

- Created a `PrometheusClient#url` method that might not be strictly
  required

- Change rescued exceptions from RestClient::* to
  HTTParty::ResponseError where possible and StandardError for the
  rest

11 files changed, 56 insertions, 32 deletions

diff --git a/spec/features/projects/services/user_activates_issue_tracker_spec.rb b/spec/features/projects/services/user_activates_issue_tracker_spec.rb
index 5803500a4d2..5f3bb794b48 100644
--- a/spec/features/projects/services/user_activates_issue_tracker_spec.rb
+++ b/spec/features/projects/services/user_activates_issue_tracker_spec.rb
@@ -61,7 +61,7 @@ describe 'User activates issue tracker', :js do
 
       context 'when the connection test fails' do
         it 'activates the service' do
-          stub_request(:head, url).to_raise(HTTParty::Error)
+          stub_request(:head, url).to_raise(Gitlab::HTTP::Error)
 
           click_link(tracker)
 
diff --git a/spec/features/projects/services/user_activates_youtrack_spec.rb b/spec/features/projects/services/user_activates_youtrack_spec.rb
index 67f0aa214e2..8fdeddfdfb4 100644
--- a/spec/features/projects/services/user_activates_youtrack_spec.rb
+++ b/spec/features/projects/services/user_activates_youtrack_spec.rb
@@ -48,7 +48,7 @@ describe 'User activates issue tracker', :js do
 
       context 'when the connection test fails' do
         it 'activates the service' do
-          stub_request(:head, url).to_raise(HTTParty::Error)
+          stub_request(:head, url).to_raise(Gitlab::HTTP::Error)
 
           click_link(tracker)
           fill_form
diff --git a/spec/lib/gitlab/bitbucket_import/importer_spec.rb b/spec/lib/gitlab/bitbucket_import/importer_spec.rb
index 62b688d4d3e..280941ff601 100644
--- a/spec/lib/gitlab/bitbucket_import/importer_spec.rb
+++ b/spec/lib/gitlab/bitbucket_import/importer_spec.rb
@@ -173,7 +173,7 @@ describe Gitlab::BitbucketImport::Importer do
     context 'when importing a pull request throws an exception' do
       before do
         allow(pull_request).to receive(:raw).and_return('hello world')
-        allow(subject.client).to receive(:pull_request_comments).and_raise(HTTParty::Error)
+        allow(subject.client).to receive(:pull_request_comments).and_raise(Gitlab::HTTP::Error)
       end
 
       it 'logs an error without the backtrace' do
diff --git a/spec/lib/gitlab/prometheus_client_spec.rb b/spec/lib/gitlab/prometheus_client_spec.rb
index f15ae83a02c..0a4e8dbced5 100644
--- a/spec/lib/gitlab/prometheus_client_spec.rb
+++ b/spec/lib/gitlab/prometheus_client_spec.rb
@@ -3,7 +3,7 @@ require 'spec_helper'
 describe Gitlab::PrometheusClient do
   include PrometheusHelpers
 
-  subject { described_class.new(RestClient::Resource.new('https://prometheus.example.com')) }
+  subject { described_class.new('https://prometheus.example.com') }
 
   describe '#ping' do
     it 'issues a "query" request to the API endpoint' do
@@ -79,8 +79,16 @@ describe Gitlab::PrometheusClient do
         expect(req_stub).to have_been_requested
       end
 
-      it 'raises a Gitlab::PrometheusClient::Error error when a RestClient::Exception is rescued' do
-        req_stub = stub_prometheus_request_with_exception(prometheus_url, RestClient::Exception)
+      it 'raises a Gitlab::PrometheusClient::Error error when a Gitlab::HTTP::ResponseError is rescued' do
+        req_stub = stub_prometheus_request_with_exception(prometheus_url, Gitlab::HTTP::ResponseError)
+
+        expect { subject }
+          .to raise_error(Gitlab::PrometheusClient::Error, "Network connection error")
+        expect(req_stub).to have_been_requested
+      end
+
+      it 'raises a Gitlab::PrometheusClient::Error error when a Gitlab::HTTP::ResponseError with a code is rescued' do
+        req_stub = stub_prometheus_request_with_exception(prometheus_url, Gitlab::HTTP::ResponseError.new(code: 400))
 
         expect { subject }
           .to raise_error(Gitlab::PrometheusClient::Error, "Network connection error")
@@ -89,13 +97,13 @@ describe Gitlab::PrometheusClient do
     end
 
     context 'ping' do
-      subject { described_class.new(RestClient::Resource.new(prometheus_url)).ping }
+      subject { described_class.new(prometheus_url).ping }
 
       it_behaves_like 'exceptions are raised'
     end
 
     context 'proxy' do
-      subject { described_class.new(RestClient::Resource.new(prometheus_url)).proxy('query', { query: '1' }) }
+      subject { described_class.new(prometheus_url).proxy('query', { query: '1' }) }
 
       it_behaves_like 'exceptions are raised'
     end
@@ -310,15 +318,32 @@ describe Gitlab::PrometheusClient do
         end
       end
 
-      context 'when RestClient::Exception is raised' do
+      context 'when Gitlab::HTTP::ResponseError is raised' do
         before do
-          stub_prometheus_request_with_exception(query_url, RestClient::Exception)
+          stub_prometheus_request_with_exception(query_url, response_error)
+        end
+
+        context "without response code" do
+          let(:response_error) { Gitlab::HTTP::ResponseError }
+          it 'raises PrometheusClient::Error' do
+            expect { subject.proxy('query', { query: prometheus_query }) }.to(
+              raise_error(Gitlab::PrometheusClient::Error, 'Network connection error')
+            )
+          end
         end
 
-        it 'raises PrometheusClient::Error' do
-          expect { subject.proxy('query', { query: prometheus_query }) }.to(
-            raise_error(Gitlab::PrometheusClient::Error, 'Network connection error')
-          )
+        context "with response code" do
+          let(:response_error) do
+            response = Net::HTTPResponse.new(1.1, 400, '{}sumpthin')
+            allow(response).to receive(:body) { '{}' }
+            Gitlab::HTTP::ResponseError.new(response)
+          end
+
+          it 'raises Gitlab::PrometheusClient::QueryError' do
+            expect { subject.proxy('query', { query: prometheus_query }) }.to(
+              raise_error(Gitlab::PrometheusClient::QueryError, 'Bad data received')
+            )
+          end
         end
       end
     end
diff --git a/spec/lib/sentry/client_spec.rb b/spec/lib/sentry/client_spec.rb
index cb14204b99a..ca2b17b44e0 100644
--- a/spec/lib/sentry/client_spec.rb
+++ b/spec/lib/sentry/client_spec.rb
@@ -63,7 +63,7 @@ describe Sentry::Client do
 
   shared_examples 'maps exceptions' do
     exceptions = {
-      HTTParty::Error => 'Error when connecting to Sentry',
+      Gitlab::HTTP::Error => 'Error when connecting to Sentry',
       Net::OpenTimeout => 'Connection to Sentry timed out',
       SocketError => 'Received SocketError when trying to connect to Sentry',
       OpenSSL::SSL::SSLError => 'Sentry returned invalid SSL data',
diff --git a/spec/models/clusters/applications/prometheus_spec.rb b/spec/models/clusters/applications/prometheus_spec.rb
index d9f31c46f59..eb6ccba5584 100644
--- a/spec/models/clusters/applications/prometheus_spec.rb
+++ b/spec/models/clusters/applications/prometheus_spec.rb
@@ -86,16 +86,15 @@ describe Clusters::Applications::Prometheus do
                project: cluster.cluster_project.project)
       end
 
-      it 'creates proxy prometheus rest client' do
-        expect(subject.prometheus_client).to be_instance_of(RestClient::Resource)
+      it 'creates proxy prometheus_client' do
+        expect(subject.prometheus_client).to be_instance_of(Gitlab::PrometheusClient)
       end
 
-      it 'creates proper url' do
-        expect(subject.prometheus_client.url).to eq("#{kubernetes_url}/api/v1/namespaces/gitlab-managed-apps/services/prometheus-prometheus-server:80/proxy")
-      end
-
-      it 'copies options and headers from kube client to proxy client' do
-        expect(subject.prometheus_client.options).to eq(kube_client.rest_client.options.merge(headers: kube_client.headers))
+      it 'copies proxy_url, options and headers from kube client to prometheus_client' do
+        expect(Gitlab::PrometheusClient)
+          .to(receive(:new))
+          .with(a_valid_url, kube_client.rest_client.options.merge(headers: kube_client.headers))
+        subject.prometheus_client
       end
 
       context 'when cluster is not reachable' do
diff --git a/spec/models/concerns/prometheus_adapter_spec.rb b/spec/models/concerns/prometheus_adapter_spec.rb
index 25a2d290f76..3d26ba95192 100644
--- a/spec/models/concerns/prometheus_adapter_spec.rb
+++ b/spec/models/concerns/prometheus_adapter_spec.rb
@@ -40,13 +40,13 @@ describe PrometheusAdapter, :use_clean_rails_memory_store_caching do
 
     describe 'matched_metrics' do
       let(:matched_metrics_query) { Gitlab::Prometheus::Queries::MatchedMetricQuery }
-      let(:prometheus_client_wrapper) { double(:prometheus_client_wrapper, label_values: nil) }
+      let(:prometheus_client) { double(:prometheus_client, label_values: nil) }
 
       context 'with valid data' do
         subject { service.query(:matched_metrics) }
 
         before do
-          allow(service).to receive(:prometheus_client_wrapper).and_return(prometheus_client_wrapper)
+          allow(service).to receive(:prometheus_client).and_return(prometheus_client)
           synchronous_reactive_cache(service)
         end
 
diff --git a/spec/models/project_services/prometheus_service_spec.rb b/spec/models/project_services/prometheus_service_spec.rb
index e9c7c94ad70..e5ac6ca65d6 100644
--- a/spec/models/project_services/prometheus_service_spec.rb
+++ b/spec/models/project_services/prometheus_service_spec.rb
@@ -105,10 +105,6 @@ describe PrometheusService, :use_clean_rails_memory_store_caching do
     context 'manual configuration is enabled' do
       let(:manual_configuration) { true }
 
-      it 'returns rest client from api_url' do
-        expect(service.prometheus_client.url).to eq(api_url)
-      end
-
       it 'calls valid?' do
         allow(service).to receive(:valid?).and_call_original
 
diff --git a/spec/services/projects/lfs_pointers/lfs_download_link_list_service_spec.rb b/spec/services/projects/lfs_pointers/lfs_download_link_list_service_spec.rb
index 80debcd3a7a..dabfd61d3f5 100644
--- a/spec/services/projects/lfs_pointers/lfs_download_link_list_service_spec.rb
+++ b/spec/services/projects/lfs_pointers/lfs_download_link_list_service_spec.rb
@@ -33,7 +33,7 @@ describe Projects::LfsPointers::LfsDownloadLinkListService do
 
   before do
     allow(project).to receive(:lfs_enabled?).and_return(true)
-    response = instance_double(HTTParty::Response)
+    response = instance_double(Gitlab::HTTP::Response)
     allow(response).to receive(:body).and_return(objects_response.to_json)
     allow(response).to receive(:success?).and_return(true)
     allow(Gitlab::HTTP).to receive(:post).and_return(response)
@@ -95,7 +95,7 @@ describe Projects::LfsPointers::LfsDownloadLinkListService do
 
     shared_examples 'JSON parse errors' do |body|
       it 'raises error' do
-        response = instance_double(HTTParty::Response)
+        response = instance_double(Gitlab::HTTP::Response)
         allow(response).to receive(:body).and_return(body)
         allow(response).to receive(:success?).and_return(true)
         allow(Gitlab::HTTP).to receive(:post).and_return(response)
diff --git a/spec/services/prometheus/proxy_service_spec.rb b/spec/services/prometheus/proxy_service_spec.rb
index 4bdb20de4c9..03bda94e9c6 100644
--- a/spec/services/prometheus/proxy_service_spec.rb
+++ b/spec/services/prometheus/proxy_service_spec.rb
@@ -131,7 +131,7 @@ describe Prometheus::ProxyService do
         allow(environment).to receive(:prometheus_adapter)
           .and_return(prometheus_adapter)
         allow(prometheus_adapter).to receive(:can_query?).and_return(true)
-        allow(prometheus_adapter).to receive(:prometheus_client_wrapper)
+        allow(prometheus_adapter).to receive(:prometheus_client)
           .and_return(prometheus_client)
       end
 
diff --git a/spec/support/matchers/be_url.rb b/spec/support/matchers/be_url.rb
index 7bd0e7fada4..69171f53891 100644
--- a/spec/support/matchers/be_url.rb
+++ b/spec/support/matchers/be_url.rb
@@ -5,3 +5,7 @@ RSpec::Matchers.define :be_url do |_|
     URI.parse(actual) rescue false
   end
 end
+
+# looks better when used like:
+#   expect(thing).to receive(:method).with(a_valid_url)
+RSpec::Matchers.alias_matcher :a_valid_url, :be_url