What is the rule syntax of whistle and what are the common operators?

Answer

Whistle's rule syntax is very concise and intuitive, with the basic format: pattern operator-uri

Basic Rule Format

shell
pattern operator-uri

• pattern: Matching pattern, can be domain, path, regular expression, etc.
• operator: Operator specifying the type of operation to perform
• uri: Target address or parameter

Common Operators

1. host: Modify request Host header

   shell
   www.example.com host 127.0.0.1:8080

2. reqHeaders: Modify request headers

   shell
   www.example.com reqHeaders://{custom-headers.json}

3. resHeaders: Modify response headers

   shell
   www.example.com resHeaders://{cors-headers.json}

4. resBody: Modify response body

   shell
   www.example.com resBody://{mock-data.json}

5. resReplace: Replace response content

   shell
   www.example.com resReplace://old-string/new-string

6. reqScript: Use script to process request

   shell
   www.example.com reqScript://{request-handler.js}

7. resScript: Use script to process response

   shell
   www.example.com resScript://{response-handler.js}

8. forward: Forward request to specified address

   shell
   www.example.com forward https://api.example.com

Matching Pattern Examples

1. Exact domain match

   shell
   www.example.com operator-uri

2. Wildcard match

   shell
   *.example.com operator-uri

3. Path match

   shell
   www.example.com/api/* operator-uri

4. Regular expression

   shell
   /^https:\/\/www\.example\.com\/api\/.*/ operator-uri

Rule Priority

Whistle matches rules in the order they appear in the configuration file, from top to bottom. Once a rule matches successfully, subsequent rules are not matched. Therefore, more specific rules should be placed earlier.

Comments and Grouping

• Use # to add comments
• Use # group-name to create groups for easier management of large numbers of rules