Attach a plugin to a Media CDN route

This page describes how to configure Service Extensions plugins in Media CDN routes.

You can use Media CDN with Service Extensions to add custom code to the request-response processing path. Such customization unlocks a wide variety of lightweight use cases.

For more information, see Media CDN extensions overview.

Before you begin

Create a Wasm action for a plugin

When creating a Wasm action, you can't use a plugin that's already in use in a Cloud Load Balancing extension.

Create a Wasm action for your Service Extensions plugin by running the gcloud alpha service-extensions wasm-actions create command:

gcloud alpha service-extensions wasm-actions create WASM_ACTION \
    --wasm-plugin=WASM_PLUGIN \
    --supported-events=[EVENT,...]

Replace the following:

WASM_ACTION: the ID or the fully qualified name of the Wasm action
WASM_PLUGIN: the name of the plugin to which you want to attach the action
EVENT: the portion of the payload to be processed by the plugin as indicated by either or both of these values: request-headers or response-headers. If not specified, both headers are processed.

It might take some time for a Wasm action to be created.

Attach a plugin to a route

To attach a plugin in a Media CDN route, follow these steps:

To export the current configuration of your service to a YAML file, run the gcloud edge-cache services export command:
```
  gcloud edge-cache services export SERVICE_NAME \
      --destination=FILENAME.yaml
```
Replace the following:
- SERVICE_NAME: the name of the Media CDN service
- FILENAME: the name of the YAML file
Use a text editor to edit the YAML file.

Update the routes in the file to add the wasmAction header as shown in the following example:

  name: SERVICE_NAME
  routing:
    hostRules:
    - hosts:
      - DOMAIN_NAME 
      pathMatcher: routes
    pathMatchers:
    - name: routes
      routeRules:
      - priority: '1'
        description: Route 1
        matchRules:
        - prefixMatch: /plugins
        origin: projects/PROJECT_NUMBER/locations/global/edgeCacheOrigins/ORIGIN_NAME
        routeAction:
          wasmAction: projects/PROJECT_NUMBER/locations/global/wasmActions/WASM_ACTION