Envoy WASM filters with Gloo

Experimental support for Envoy WASM filters has been added to Open Source Gloo as of version 1.2.6. This guide is specifically for Gloo 1.5.x, as there have been some changes to the configuration API since prior versions.

This feature is considered incredibly experimental. It uses a fork of Envoy which does not have any official support. It is meant to show off the potential of WASM filters, and how they will integrate with Gloo going forward.


Getting started with WASM is simple, it requires setting one new value in the gloo helm chart.

Gloo can be installed with this value set using either glooctl or helm 3 as follows:

glooctl install gateway --values <(echo '{"crds":{"create":true},"global":{"wasm":{"enabled":true}}}')

helm repo add gloo https://storage.googleapis.com/solo-public-helm

helm repo update
kubectl create ns gloo-system
helm install --namespace gloo-system --version v1.5.0-beta13 --set global.wasm.enabled=true gloo gloo/gloo

Once this process has been completed, gloo should be up and running in the gloo-system namespace.

To check run the following:

kubectl get pods -n gloo-system
NAME                            READY   STATUS    RESTARTS   AGE
discovery-5ff9ddbc8f-p7njb      1/1     Running   0          45s
gateway-578f5b7d9d-khw8m        1/1     Running   0          45s
gateway-proxy-c9b4cc476-x6h5j   1/1     Running   0          45s
gloo-6889d56b5c-f28gv           1/1     Running   0          45s

Once all of the pods are up and running you are all ready to configure your first WASM filter. The API to configure the filter can be found here .

At the moment the config must live on the gateway level, this will change as the Envoy WASM api evolves. To configure a gateway to add a WASM filter, the gateway must be edited like so.

kubectl edit -n gloo-system gateways.gateway.solo.io gateway-proxy

and change the httpGateway object to the following:

        - config:
            '@type': type.googleapis.com/google.protobuf.StringValue
            value: "world"
          image: webassemblyhub.io/sodman/example-filter:v0.3
          name: myfilter
          root_id: add_header_root_id

Once that is saved, the hard work has been done. All traffic on the http gateway will call the wasm filter.

To find our more information about WASM filters, and how to build/run them check out wasme.

wasme is a tool for building and deploying Envoy WASM filters, in Gloo, and in vanilla Envoy. Much more detailed information can be found there on how the filters work.

To find more information about WASM filters, and find more filters which can be included in Gloo check out WebAssembly Hub!.