feat(logs): support regex patterns for JSON Metrics filters

packages/aws-cdk-lib/aws-logs/lib/pattern.ts

@@ -117,6 +117,27 @@ export class FilterPattern {
     return new JSONNumberPattern(jsonField, comparison, value);
   }
 
+  /**
+   * A JSON log pattern that compares against a Regex values.
+   *
+   * This pattern only matches if the event is a JSON event, and the indicated field inside
+   * compares with the regex value.
+   *
+   * Use '$' to indicate the root of the JSON structure. The comparison operator can only
+   * compare equality or inequality.
+   *
+   * For more information, see:
+   *
+   * https://docs.aws.amazon.com/AmazonCloudWatch/latest/logs/FilterAndPatternSyntax.html
+   *
+   * @param jsonField Field inside JSON. Example: "$.myField"
+   * @param comparison Comparison to carry out. Either = or !=.
+   * @param value The regex value to compare to.
+   */
+  public static regexValue(jsonField: string, comparison: string, value: string): JsonPattern {
+    return new JSONRegexPattern(jsonField, comparison, value);
+  }
+
   /**
    * A JSON log pattern that matches if the field exists and has the special value 'null'.
    *
@@ -226,6 +247,16 @@ class JSONStringPattern extends JsonPattern {
   }
 }
 
+/**
+ * A regex comparison for JSON patterns
+ */
+class JSONRegexPattern extends JsonPattern {
+  public constructor(jsonField: string, comparison: string, value: string) {
+    // No validation, we assume these are generated by trusted factory functions
+    super(`${jsonField} ${comparison} %${value}%`);
+  }
+}
+
 /**
  * A number comparison for JSON values
  */