Using the Wasm Filter

The WebAssembly (Wasm) filter type implements Envoy's Wasm filter, and it can be used to apply an HTTP filter with a Wasm plugin. The Wasm filter is used in conjunction with the EnvoyFilter and EnvoyFilterPolicy custom resources to introduce additional processing for incoming or outgoing traffic while maintaining the flow of requests. This allows you to implement highly specific, custom logic.

The EnvoyFilterPolicy Resource

Similar to the FilterPolicy resource, you can use the EnvoyFilterPolicy resource to determine how to apply Envoy filters to HTTP requests.

For example:

Note: For information on all supported fields, see EnvoyFilterPolicy.

The Wasm Resource

To use the Wasm filter type, you must mount a .wasm file to Ambassador Edge Stack's pod by creating a configMap with the --from-file flag and then referencing that configMap from Ambassador Edge Stack's deployment spec.

First, create the configMap that references your Wasm filter.

Second, edit the deployment to add a volumeMount that references the configmap.

Finally, configure the EnvoyFilter to reference the Wasm filter that you mounted.