Merge branch '220144-substitute-variables-in-alerts' into 'master'

Use ProxyVariableSubstitutionService for variable substitution in alerts

See merge request gitlab-org/gitlab!33772

app/services/clusters/applications/prometheus_config_service.rb

@@ -132,19 +132,21 @@ module Clusters
       end
 
       def alerts(environment)
-        variables = Gitlab::Prometheus::QueryVariables.call(environment)
         alerts = Projects::Prometheus::AlertsFinder
           .new(environment: environment)
           .execute
 
         alerts.map do |alert|
-          substitute_query_variables(alert.to_param, variables)
+          hash = alert.to_param
+          hash['expr'] = substitute_query_variables(hash['expr'], environment)
+          hash
         end
       end
 
-      def substitute_query_variables(hash, variables)
-        hash['expr'] %= variables
-        hash
+      def substitute_query_variables(query, environment)
+        result = ::Prometheus::ProxyVariableSubstitutionService.new(environment, query: query).execute
+
+        result[:params][:query]
       end
 
       def environments

changelogs/unreleased/220144-substitute-variables-in-alerts.yml

+---
+title: Fix bug with variable substitution in alerts
+merge_request: 33772
+author:
+type: fixed

spec/services/clusters/applications/prometheus_config_service_spec.rb

@@ -90,23 +90,25 @@ describe Clusters::Applications::PrometheusConfigService do
             create(:prometheus_alert,
                    project: project,
                    environment: production,
-                   prometheus_metric: metric)
+                   prometheus_metric: metric,
+                   operator: PrometheusAlert.operators['gt'],
+                   threshold: 0)
           end
 
           let(:metric) do
             create(:prometheus_metric, query: query, project: project)
           end
 
-          let(:query) { '%{ci_environment_slug}' }
+          let(:query) { 'up{environment="{{ci_environment_slug}}"}' }
 
           it 'substitutes query variables' do
             expect(Gitlab::Prometheus::QueryVariables)
               .to receive(:call)
-              .with(production)
+              .with(production, start_time: nil, end_time: nil)
               .and_call_original
 
             expr = groups.dig(0, 'rules', 0, 'expr')
-            expect(expr).to include(production.name)
+            expect(expr).to eq("up{environment=\"#{production.slug}\"} > 0.0")
           end
         end
 
@@ -127,13 +129,15 @@ describe Clusters::Applications::PrometheusConfigService do
           end
 
           it 'substitutes query variables once per environment' do
+            allow(Gitlab::Prometheus::QueryVariables).to receive(:call).and_call_original
+
             expect(Gitlab::Prometheus::QueryVariables)
               .to receive(:call)
-              .with(production)
+              .with(production, start_time: nil, end_time: nil)
 
             expect(Gitlab::Prometheus::QueryVariables)
               .to receive(:call)
-              .with(staging)
+              .with(staging, start_time: nil, end_time: nil)
 
             subject
           end