prometheus: query field: better handle label-values with unusual characters (#41457)

public/app/plugins/datasource/prometheus/components/monaco-query-field/monaco-completion-provider/completions.ts

@@ -2,6 +2,7 @@ import type { Situation, Label } from './situation';
 import { NeverCaseError } from './util';
 // FIXME: we should not load this from the "outside", but we cannot do that while we have the "old" query-field too
 import { FUNCTIONS } from '../../../promql';
+import { escapeLabelValueInExactSelector } from '../../../language_utils';
 
 export type CompletionType = 'HISTORY' | 'FUNCTION' | 'METRIC_NAME' | 'DURATION' | 'LABEL_NAME' | 'LABEL_VALUE';
 
@@ -90,7 +91,9 @@ function makeSelector(metricName: string | undefined, labels: Label[]): string {
     allLabels.push({ name: '__name__', value: metricName, op: '=' });
   }
 
-  const allLabelTexts = allLabels.map((label) => `${label.name}${label.op}"${label.value}"`);
+  const allLabelTexts = allLabels.map(
+    (label) => `${label.name}${label.op}"${escapeLabelValueInExactSelector(label.value)}"`
+  );
 
   return `{${allLabelTexts.join(',')}}`;
 }

public/app/plugins/datasource/prometheus/components/monaco-query-field/monaco-completion-provider/situation.test.ts

@@ -89,6 +89,24 @@ describe('situation', () => {
       type: 'IN_LABEL_SELECTOR_NO_LABEL_NAME',
       otherLabels: [{ name: 'one', value: 'val1', op: '=' }],
     });
+
+    // single-quoted label-values with escape
+    assertSituation("{one='val\\'1',^}", {
+      type: 'IN_LABEL_SELECTOR_NO_LABEL_NAME',
+      otherLabels: [{ name: 'one', value: "val'1", op: '=' }],
+    });
+
+    // double-quoted label-values with escape
+    assertSituation('{one="val\\"1",^}', {
+      type: 'IN_LABEL_SELECTOR_NO_LABEL_NAME',
+      otherLabels: [{ name: 'one', value: 'val"1', op: '=' }],
+    });
+
+    // backticked label-values with escape (the escape should not be interpreted)
+    assertSituation('{one=`val\\"1`,^}', {
+      type: 'IN_LABEL_SELECTOR_NO_LABEL_NAME',
+      otherLabels: [{ name: 'one', value: 'val\\"1', op: '=' }],
+    });
   });
 
   it('handles label values', () => {

public/app/plugins/datasource/prometheus/components/monaco-query-field/monaco-completion-provider/situation.ts

@@ -63,17 +63,34 @@ function getNodeText(node: SyntaxNode, text: string): string {
 }
 
 function parsePromQLStringLiteral(text: string): string {
+  // if it is a string-literal, it is inside quotes of some kind
+  const inside = text.slice(1, text.length - 1);
+
   // FIXME: support https://prometheus.io/docs/prometheus/latest/querying/basics/#string-literals
   // FIXME: maybe check other promql code, if all is supported or not
+
+  // for now we do only some very simple un-escaping
+
   // we start with double-quotes
   if (text.startsWith('"') && text.endsWith('"')) {
-    if (text.indexOf('\\') !== -1) {
-      throw new Error('FIXME: escape-sequences not supported in label-values');
-    }
-    return text.slice(1, text.length - 1);
-  } else {
-    throw new Error('FIXME: invalid string literal');
+    // NOTE: this is not 100% perfect, we only unescape the double-quote,
+    // there might be other characters too
+    return inside.replace(/\\"/, '"');
   }
+
+  // then single-quote
+  if (text.startsWith("'") && text.endsWith("'")) {
+    // NOTE: this is not 100% perfect, we only unescape the single-quote,
+    // there might be other characters too
+    return inside.replace(/\\'/, "'");
+  }
+
+  // then backticks
+  if (text.startsWith('`') && text.endsWith('`')) {
+    return inside;
+  }
+
+  throw new Error('FIXME: invalid string literal');
 }
 
 type LabelOperator = '=' | '!=' | '=~' | '!~';