Configure origin HTTP request headers-阿里云帮助中心

By default, Alibaba Cloud and DCDN support request headers that carry information, such as the client IP address. You can also configure custom headers. To customize origin requests, use the Modify Outgoing Request Header feature to add, delete, change, or replace HTTP request headers.

Prerequisites

This feature is not enabled by default. To use this feature for a domain, you must first submit a ticket to enable it.

Background

An HTTP request header is part of an HTTP request message. It passes specific parameters to a server.

When a or DCDN point of presence (POP) requests resources from an origin server, the server can read the information in the origin request header. This feature lets you rewrite HTTP request headers in origin requests to send specific parameters to the origin server.

To learn how an origin server reads the client IP address from the X-Forwarded-For header, see Obtain the client IP address.

Usage notes

An outgoing request is an HTTP message that is sent back to the origin server through or DCDN. The configuration for modifying outgoing request headers affects only HTTP messages that are sent back to the origin server through or DCDN. This configuration does not modify HTTP messages that are served directly to users from or DCDN nodes.
You cannot modify outgoing request headers for a wildcard domain name.

Alibaba Cloud and DCDN include the following HTTP request headers in origin requests by default, requiring no additional configuration.

Origin HTTP header	Description	Example
Ali-Cdn-Real-Ip	The client's real IP address for the connection to a or DCDN POP.	Ali-Cdn-Real-Ip:192.168.0.1
X-Forwarded-For	The IP addresses of the client and any intermediate or DCDN POPs.	X-Forwarded-For:192.168.0.1, 172.16.0.1
X-Client-Scheme	The application-layer protocol used by the client to send a request to a or DCDN POP, such as HTTP or HTTPS.	X-Client-Scheme:http
Host	The domain name of the origin server accessed in the origin request.	Host:example.com
Via	The names of all or DCDN POPs through which the client request passes.	Via:cn2546-10.l1, cache1.cn2546-10, l2cn2547-7.l2, cache1.l2cn2547-7

If you set the value of an outgoing request header to a variable, the variable is resolved to its actual value at runtime. The following variables are available.

Parameter	Origin HTTP header	Description	Example
Ali-Cdn-Real-Port	$http_Ali_Cdn_Real_Port	Adds the client's real port to the origin request header.	Ali-Cdn-Real-Port:80
Ali-Cdn-Real-Ip	$http_Ali_Cdn_Real_Ip	Adds the client's real IP address to the origin request header.	Ali-Cdn-Real-Ip:192.168.0.1
X-Forwarded-For	$proxy_add_x_forwarded_for	Adds the X-Forwarded-For header to the origin request to pass the client IP address and the intermediate proxy IP address to the origin server.	X-Forwarded-For:192.168.0.1, 172.16.0.1

Procedure

Log on to the DCDN console.
In the left-side navigation pane, click Domain Names.
On the Domain Names page, find the domain name that you want to manage and click Configure in the Actions column.
In the domain's navigation pane, click Origin Fetch.
Click the Modify Outgoing Request Header tab.
On the Modify Outgoing Request Header tab, click Add.

Configure the parameters for the header modification.

Important

If multiple conflicting operations target the same origin request header, only the one with the highest priority is executed. The priority order from highest to lowest is: Replace > Add > Change/Delete. For example, if you configure both an Add and a Delete operation for the same header, only the Add operation is executed.

Add request header

Parameter	Example	Description
Operation	Add	Adds the specified header to origin HTTP requests.
Request header	Custom header	Select a preset request header or select Custom header.
Request header name	x-code	The name of the custom request header. In this example, `x-code`.
Header value	key1	You can specify one or more values. Separate multiple values with a comma (,).
Header value	key1, key2
Allow duplicates	Yes	Yes: Allows adding duplicate request headers. For example, `x-code:key1` and `x-code:key2`. No: If you add a header with the same name as an existing header, the new value overwrites the old one. For example, if you first add `x-code:key1` and then add `x-code:key2`, the final header is `x-code:key2`.

Delete request header

Parameter	Example	Description
Operation	Delete	Deletes all header values that match the specified header name, including any duplicates.
Request header	Custom header	Select a preset request header or select Custom header.
Request header name	x-code	The name of the custom request header. In this example, `x-code`.

Change request header

Parameter	Example	Description
Operation	Change	Changes the value of a header. This operation is not allowed if multiple headers with the same name exist.
Request header	Custom header	Select a preset request header or select Custom header.
Request header name	x-code	The name of the custom request header. In this example, `x-code`.
Change to	key1, key3	You can specify one or more values. Separate multiple values with a comma (,).

Replace request header

Parameter	Example	Description
Operation	Replace	Replaces part of a header's value by using a regular expression. This operation is not allowed if multiple headers with the same name exist.
Request header	Custom header	Select a preset request header or select Custom header.
Request header name	x-code	The name of the custom request header. In this example, `x-code`.
Find	key	A regular expression to find the value to be replaced.
Replace with	abc	The string to replace the matched text. Regular expression back-references are supported.
Match	Match All	Match All: Replaces all matched values. For example, if you replace "key" with "abc" in `x-code:key1,key2,key3`, the result is `x-code:abc1,abc2,abc3`. Match the First Only: Replaces only the first matched value. For example, if you replace "key" with "abc" in `x-code:key1,key2,key3`, the result is `x-code:abc1,key2,key3`.

Click OK.

Related API

BatchSetDcdnDomainConfigs