Merge branch 'rp-use-gitlab-yaml-loader-blob-viewer' into 'master'

Use the Gitlab yaml loader in metrics dashboard blob viewer

See merge request gitlab-org/gitlab!34199

app/models/blob_viewer/metrics_dashboard_yml.rb

@@ -25,9 +25,11 @@ module BlobViewer
     private
 
     def parse_blob_data
-      ::PerformanceMonitoring::PrometheusDashboard.from_json(YAML.safe_load(blob.data))
+      yaml = ::Gitlab::Config::Loader::Yaml.new(blob.data).load_raw!
+
+      ::PerformanceMonitoring::PrometheusDashboard.from_json(yaml)
       nil
-    rescue Psych::SyntaxError => error
+    rescue Gitlab::Config::Loader::FormatError => error
       wrap_yml_syntax_error(error)
     rescue ActiveModel::ValidationError => invalid
       invalid.model.errors

changelogs/unreleased/rp-use-gitlab-yaml-loader-blob-viewer.yml

+---
+title: Display error for YAML files that are too large
+merge_request: 34199
+author:
+type: changed

doc/user/project/integrations/prometheus.md

@@ -361,6 +361,13 @@ When **Metrics Dashboard YAML definition is invalid** at least one of the follow
 1. `query: can't be blank` [learn more](#metrics-metrics-properties)
 1. `query_range: can't be blank` [learn more](#metrics-metrics-properties)
 1. `unit: can't be blank` [learn more](#metrics-metrics-properties)
+1. `YAML syntax: The parsed YAML is too big`
+
+   This is displayed when the YAML file is larger than 1 MB.
+
+1. `YAML syntax: Invalid configuration format`
+
+   This is displayed when the YAML file is empty or does not contain valid YAML.
 
 Metrics Dashboard YAML definition validation information is also available as a [GraphQL API field](../../../api/graphql/reference/index.md#metricsdashboard)
 

spec/models/blob_viewer/metrics_dashboard_yml_spec.rb

@@ -24,9 +24,16 @@ describe BlobViewer::MetricsDashboardYml do
         viewer.valid?
       end
 
-      it 'returns true' do
+      it 'returns true', :aggregate_failures do
+        yml = ::Gitlab::Config::Loader::Yaml.new(data).load_raw!
+
+        expect_next_instance_of(::Gitlab::Config::Loader::Yaml, data) do |loader|
+          expect(loader).to receive(:load_raw!).and_call_original
+        end
         expect(PerformanceMonitoring::PrometheusDashboard)
-          .to receive(:from_json).with(YAML.safe_load(data))
+          .to receive(:from_json)
+          .with(yml)
+          .and_call_original
         expect(viewer.valid?).to be_truthy
       end
     end
@@ -92,4 +99,29 @@ describe BlobViewer::MetricsDashboardYml do
       end
     end
   end
+
+  context 'when YAML loader raises error' do
+    let(:data) do
+      <<~YAML
+        large yaml file
+      YAML
+    end
+
+    before do
+      allow(::Gitlab::Config::Loader::Yaml).to receive(:new)
+        .and_raise(::Gitlab::Config::Loader::Yaml::DataTooLargeError, 'The parsed YAML is too big')
+    end
+
+    it 'is invalid' do
+      expect(PerformanceMonitoring::PrometheusDashboard).not_to receive(:from_json)
+      expect(viewer.valid?).to be(false)
+    end
+
+    it 'returns validation errors' do
+      yaml_wrapped_errors = { 'YAML syntax': ["The parsed YAML is too big"] }
+
+      expect(viewer.errors).to be_kind_of(ActiveModel::Errors)
+      expect(viewer.errors.messages).to eq(yaml_wrapped_errors)
+    end
+  end
 end