Variables overview

Variables give you more control over your configuration. They provide more flexibility when using existing advanced metadata through the use of input/output variables. Create complex properties without the need to implement advanced metadata.

Variables allow you to:

  • Make a complex forward path modification

  • Select origin based on a pattern

  • Read, add, and modify HTTP headers and cookies

  • Input to advanced metadata

  • Output from advanced metadata to drive further behaviors


Variable support is available for certain products. If you don't see variable support listed as an available module for a product, contact your account representative to learn more.

You can use built-in variables right away, but to add a user-defined variable to a behavior, first you need to create one.

Notes and restrictions

  • A value has a maximum size limit of 8k per variable. Using advanced metadata, the size limit is 16k. Contact your account support representative for help configuring advanced metadata.

  • Variable support includes request-stage built-in variables only. For information or assistance with variables form any other stage, contact your account support representative.

  • Variable support does not currently distinguish our parent edge servers from our child edge servers. If you need to distinguish between these types of servers, for instance to implement a different functionality, contact your support representative.

Variable types

There are two types of variables. Built-in variables that are read-only variables that address common information about each request, and user-defined variables that you can create, edit, or otherwise modify.

Behaviors that support variables

Many Property Manager behaviors have fields that support the use of variables โ€“ they show the "(variable support)" note under the text field. The following behaviors accept variables:

  • Construct Response

  • Modify Incoming Request Header

  • Modify Incoming Response Header

  • Modify Outgoing Request Header

  • Modify Outgoing Response Header

  • Modify Outgoing Request Path

  • Origin Base Path

  • Origin Server

  • Redirect

  • Redirect Plus

  • Set Response Cookie

  • Set Variable

  • Site Failover


Use the following syntax in any of the behaviors that allow variable support.


Where variable type is either "built-in" or "user".

The built-in variables correspond to underlying metadata variables, typically prefixed with AK_. For instance,{{builtin.AK_PATH}}corresponds to the %(AK_PATH)metadata variable.

The global user variables are prefixed with PMUSER_ in the underlying metadata, for instance, {{user.PMUSER_FOO}}corresponds to %(PMUSER_FOO)in metadata syntax.

The local user variables you create on an include level are prefixed with PMINC_<includeId> in the underlying metadata, for instance {{user.PMINC_inc_12345}}corresponds to %(user.PMINC_inc_12345) in metadata syntax.

Here is an example variable expression syntax that includes a builtin variable, a fixed string, and a user defined variable: