Apigee provides a range of out-of-the-box policy capabilities that address common API management requirements. However, there are some cases where your API requires custom behavior that is not covered by Apigee's standard policy palette. In these cases, Apigee exposes scripting interfaces to ease the task of implementing custom behaviors in the proxied API message flow. One approach is to attach your own Python script to an API flow, which the API Platform then executes at runtime.
A Python policy contains no actual code. Instead, a Python policy references a Python 'resource' and defines the Step in the API flow where the Python script executes. You can upload your script through the Management UI proxy editor, or you can include it in the
/resources/py directory in API proxies that you develop locally.
This policy is available on Apigee Edge paid plans only. To enable this policy in your environment, contact Apigee Support.
System calls, for example network I/O, filesystem read/writes, current user info, process list, and CPU/memory utilization are not permitted by the security model. Although some such calls may be functional, they are unsupported and liable to be actively disabled at any time. For forward compatibility, you should avoid making such calls in your Python scripts.
For working sample Python scripts, see Samples reference.
Configure the Python Script policy using the following elements.
name attribute for this policy is restricted to these characters:
A-Z0-9._\-$ %. However, the Management UI enforces additional restrictions, such as automatically removing characters that are not alphanumeric.
|ResourceURL||Specifies the name of the Python script stored in the API proxy under
|IncludeURL (Optional)||You can include zero or more of these elements. Each elemnt should specify a single Python script in the same form as the
Example - Python Script policy
In the example below, the element, ResourceURL specifies the relevant Python script resource.
<?xml version="1.0" encoding="UTF-8" standalone="yes"?> <Script name="Python-1"> <DisplayName>Python-1</DisplayName> <FaultRules/> <ResourceURL>py://myscript.py</ResourceURL> </Script>
Example - Python Script
This shows what you might include in the python script itself.
import base64 username = flow.getVariable("request.formparam.client_id") password = flow.getVariable("request.formparam.client_secret") base64string = base64.encodestring('%s:%s' % (username, password))[:-1] authorization = "Basic "+base64string flow.setVariable("authorizationParam",authorization)
Each policy must conform to a policy schema. All policy constructs such as elements and attributes mentioned above are defined in a schema. To download the schema, click here.
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