Advanced Forwarding

Forwarding rule

The following forwarding rules are supported: domain name, path, HTTP request method, HTTP header, query string, cookie, and CIDR block.

For details, see Forwarding Rule.

Action

The following actions are supported: forward to a backend server group, redirect to another listener, redirect to another URL, rewrite, write header, remove header, limit request, and return a specific response body.

NOTE:

• If Action is set to Forward to a backend server group, you can also select from one of the following additional actions: rewrite, write header, remove header, and limit request.
• If Action is set to Return a specific response body, you can also select the additional action Limit request.

For details, see Table 4.

For details, see Action Types.

Domain name

• Description

  Route requests based on the domain name. You can configure multiple domain names with each consist of at least two labels separated by periods (.). Max total: 100 characters. Max label: 63 characters.

• Matching rules
  • Exact match and wildcard match: The domain name can contain only letters, digits, and special characters .-?=~_+\^*!$&|()[]. Asterisks (*) and question marks (?) can be used as wildcards. The domain name cannot start or end with a period (.) or contain two consecutive periods (..).
  • Regular expression match: The domain name can contain only letters, digits, and special characters .-?=~_+\^*!$&|()[].

Example
Request URL: https://www.example.com/login.php?locale=en-us=#videos
Domain name in the forwarding rule: www.example.com

Path

• Description

  Route requests based on paths. You can configure multiple paths in a forwarding policy. Each path contains 1 to 128 characters, including letters, digits, and special characters: _~';@^-%#$.*+?,=!:|\/()[]{}

• Matching rules
  • Exact match: The request path must exactly match that specified in the forwarding policy. The URL must start with a slash (/) and can use asterisks (*) and question marks (?) as wildcards.
  • Prefix match: The request path starts with the specified path string. The URL must start with a slash (/) and can use asterisks (*) and question marks (?) as wildcards.
  • Regular expression match: The URLs are matched using a regular expression.

For more information about path matching rules, see Path Matching.

Example path:
Request URL: https://www.example.com/login.php?locale=en-us#videos
Path in the forwarding rule: /login.php

Query string

Route requests based on the query string.

Example
Request URL: https://www.example.com/login.php?locale=en-us#videos
A query string needs to be configured for the forwarding rule:
Key: locale
Value: en-us

HTTP request method

Route requests based on the HTTP method.

• You can configure multiple request methods in a forwarding policy.
• The following methods are available: GET, POST, PUT, DELETE, PATCH, HEAD, and OPTIONS.

Example
GET

HTTP header

Route requests based on the HTTP header.

Example
Key: Accept-Language
Value: en-us

CIDR block

Route requests based on the source IP addresses from where requests originate.

Example
192.168.1.0/24 or 2020:50::44/127

Cookie

Route requests based on the cookie.

A cookie consists of a key and a value. You need to configure the key and value separately.

• A key can contain 1 to 100 characters and cannot start or end with a space.
• A key can have one value, which can contain 1 to 100 characters.

You can enter multiple key-value pairs. The key-value pairs can contain letters, digits, and special characters !%'"()*+,./:=?@^-_`~

Example:
Key: cookie_name
Value: cookie_value

Forward to a backend server group

Requests are forwarded to the specified backend server group.

NOTE:

If Action is set to Forward to a backend server group, you can also select from one of the following additional actions: rewrite, write header, remove header, and limit request.

For details, see Table 4.

Redirect to another listener

Requests are redirected to another listener, which then routes the requests to its associated backend server group.

NOTE:

If you select Redirect to another listener, the configurations for the HTTP listener will not be applied, but access control configured for the listener will still be applied.

For example, if you configure a redirect for an HTTP listener, HTTP requests to access a web page will be redirected to the HTTPS listener you select and handled by the backend servers associated with the HTTPS listener. As a result, the clients access the web page over HTTPS.

Redirect to another URL

Requests are redirected to the configured URL.

When clients access website A, the load balancer returns 302 or any other 3xx status code and automatically redirects the clients to website B. You can customize the redirection URL that will be returned to the clients.

Example
URL for redirection: http://www.example1.com/index.html?locale=en-us#videos
Protocol: HTTP
Domain name: www.example1.com
Port: 8081
Path: /index.html
Query String: locale=en-us
HTTP Status Code: 301

Return a specific response body

Load balancers return a fixed response to the clients.

You can custom the status code and response body that load balancers directly return to the clients without the need to route the requests to backend servers.

NOTE:

If Action is set to Return a specific response body, you can also select the additional action Limit request.

For details, see Table 4.

Example

text/plain

Sorry, the language is not supported.

text/css

<head><style type="text/css">div {background-color:red}#div {font-size:15px;color:red}</style></head>

text/html

<form action="/" method="post" enctype="multipart/form-data"><input type="text" name="description" value="some text"><input type="file" name="myFile"><button type="submit">Submit</button></form>

NOTE:

To display languages other than English, you are advised to add <meta charset="utf-8"> to the message body. If you do not do this, the languages may appear as garbled characters.