Alerting: Fix RegExp matchers in frontend for Silences and other previews. (#51726)

public/app/features/alerting/unified/utils/matchers.test.ts

@@ -56,27 +56,38 @@ describe('Unified Alerting matchers', () => {
     });
 
     it('should match for regex', () => {
-      const matchers = [{ name: 'foo', value: 'bar', operator: MatcherOperator.regex }];
+      const matchers = [{ name: 'foo', value: 'b{1}a.*', operator: MatcherOperator.regex }];
       const alerts = [
+        mockPromAlert({ labels: { foo: 'bbr' } }),
+        mockPromAlert({ labels: { foo: 'aba' } }), // This does not match because the regex is implicitly anchored.
+        mockPromAlert({ labels: { foo: 'ba' } }),
         mockPromAlert({ labels: { foo: 'bar' } }),
         mockPromAlert({ labels: { foo: 'baz' } }),
         mockPromAlert({ labels: { foo: 'bas' } }),
       ];
 
       const matchedAlerts = findAlertInstancesWithMatchers(alerts, matchers);
-      expect(matchedAlerts).toHaveLength(1);
+      expect(matchedAlerts).toHaveLength(4);
+      expect(matchedAlerts.map((instance) => instance.data.matchedInstance.labels.foo)).toEqual([
+        'ba',
+        'bar',
+        'baz',
+        'bas',
+      ]);
     });
 
     it('should not match regex', () => {
-      const matchers = [{ name: 'foo', value: 'bar', operator: MatcherOperator.notRegex }];
+      const matchers = [{ name: 'foo', value: 'ba{3}', operator: MatcherOperator.notRegex }];
       const alerts = [
         mockPromAlert({ labels: { foo: 'bar' } }),
         mockPromAlert({ labels: { foo: 'baz' } }),
+        mockPromAlert({ labels: { foo: 'baaa' } }),
         mockPromAlert({ labels: { foo: 'bas' } }),
       ];
 
       const matchedAlerts = findAlertInstancesWithMatchers(alerts, matchers);
-      expect(matchedAlerts).toHaveLength(2);
+      expect(matchedAlerts).toHaveLength(3);
+      expect(matchedAlerts.map((instance) => instance.data.matchedInstance.labels.foo)).toEqual(['bar', 'baz', 'bas']);
     });
   });
 });

public/app/features/alerting/unified/utils/matchers.ts

@@ -41,29 +41,44 @@ export const findAlertInstancesWithMatchers = (
   instances: Alert[],
   matchers: MatcherFieldValue[]
 ): MatchedInstance[] => {
-  const hasMatcher = (instance: Alert, matcher: MatcherFieldValue) => {
+  const anchorRegex = (regexpString: string): RegExp => {
+    // Silence matchers are always fully anchored in the Alertmanager: https://github.com/prometheus/alertmanager/pull/748
+    if (!regexpString.startsWith('^')) {
+      regexpString = '^' + regexpString;
+    }
+    if (!regexpString.endsWith('$')) {
+      regexpString = regexpString + '$';
+    }
+    return new RegExp(regexpString);
+  };
+
+  const matchesInstance = (instance: Alert, matcher: MatcherFieldValue) => {
     return Object.entries(instance.labels).some(([key, value]) => {
       if (!matcher.name || !matcher.value) {
         return false;
       }
-      if (matcher.operator === MatcherOperator.equal) {
-        return matcher.name === key && matcher.value === value;
-      }
-      if (matcher.operator === MatcherOperator.notEqual) {
-        return matcher.name === key && matcher.value !== value;
-      }
-      if (matcher.operator === MatcherOperator.regex) {
-        return matcher.name === key && matcher.value.match(value);
+      if (matcher.name !== key) {
+        return false;
       }
-      if (matcher.operator === MatcherOperator.notRegex) {
-        return matcher.name === key && !matcher.value.match(value);
+      switch (matcher.operator) {
+        case MatcherOperator.equal:
+          return matcher.value === value;
+        case MatcherOperator.notEqual:
+          return matcher.value !== value;
+        case MatcherOperator.regex:
+          const regex = anchorRegex(matcher.value);
+          return regex.test(value);
+        case MatcherOperator.notRegex:
+          const negregex = anchorRegex(matcher.value);
+          return !negregex.test(value);
+        default:
+          return false;
       }
-      return false;
     });
   };
 
   const filteredInstances = instances.filter((instance) => {
-    return matchers.every((matcher) => hasMatcher(instance, matcher));
+    return matchers.every((matcher) => matchesInstance(instance, matcher));
   });
   const mappedInstances = filteredInstances.map((instance) => ({
     id: `${instance.activeAt}-${instance.value}`,