Alerting: do not unescape external AM label values (#45334)

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

@@ -31,16 +31,23 @@ describe('Alertmanager utils', () => {
       });
     });
 
-    it('should parse escaped values correctly', () => {
-      expect(parseMatcher('foo=~"bar\\"baz\\""')).toEqual<Matcher>({
+    // Alertmanager has some strict requirements for label values;
+    // we should not automatically encode or decode any values sent
+    // and instead let AM return any errors like (matcher value contains unescaped double quote: bar"baz")
+    // and allow the user to update the values to the correct format
+    //
+    // see https://github.com/prometheus/alertmanager/blob/4030e3670b359b8814aa8340ea1144f32b1f5ab3/pkg/labels/parse.go#L55-L99
+    // and https://github.com/prometheus/alertmanager/blob/4030e3670b359b8814aa8340ea1144f32b1f5ab3/pkg/labels/parse.go#L101-L178
+    it('should not parse escaped values', () => {
+      expect(parseMatcher('foo="^[a-z0-9-]{1}[a-z0-9-]{0,30}$"')).toEqual<Matcher>({
         name: 'foo',
-        value: 'bar"baz"',
-        isRegex: true,
+        value: '"^[a-z0-9-]{1}[a-z0-9-]{0,30}$"',
+        isRegex: false,
         isEqual: true,
       });
       expect(parseMatcher('foo=~bar\\"baz\\"')).toEqual<Matcher>({
         name: 'foo',
-        value: 'bar"baz"',
+        value: 'bar\\"baz\\"',
         isRegex: true,
         isEqual: true,
       });

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

@@ -118,14 +118,6 @@ const matcherOperators = [
   MatcherOperator.equal,
 ];
 
-function unescapeMatcherValue(value: string) {
-  let trimmed = value.trim().replace(/\\"/g, '"');
-  if (trimmed.startsWith('"') && trimmed.endsWith('"') && !trimmed.endsWith('\\"')) {
-    trimmed = trimmed.substr(1, trimmed.length - 2);
-  }
-  return trimmed.replace(/\\"/g, '"');
-}
-
 export function parseMatcher(matcher: string): Matcher {
   const trimmed = matcher.trim();
   if (trimmed.startsWith('{') && trimmed.endsWith('}')) {
@@ -141,7 +133,7 @@ export function parseMatcher(matcher: string): Matcher {
   }
   const [operator, idx] = operatorsFound[0];
   const name = trimmed.substr(0, idx).trim();
-  const value = unescapeMatcherValue(trimmed.substr(idx + operator.length).trim());
+  const value = trimmed.substr(idx + operator.length).trim();
   if (!name) {
     throw new Error(`Invalid matcher: ${trimmed}`);
   }