WebAssembly brings extensibility to network proxies

Thursday, March 12, 2020

With the Istio 1.5 release we are happy to introduce WebAssembly (Wasm) extensions in Envoy, built with our long running collaborators Lyft and IBM. With partners like deepening their engagement as well, we are excited to see the community and ecosystem developing around this segment of the open source world.

The Envoy service proxy has taken the Cloud Native landscape by storm since it was open sourced by Lyft in 2016, quickly becoming a fixture in modern app deployment—both at the edge and as a sidecar. Since Google and IBM started the Istio project and selected Envoy as the proxy of choice for service mesh, we have been working with the Envoy community to improve performance and add functionality. In fact, Google now commits more code to Envoy than any other company.

Envoy has always had an extension mechanism, either with compiled-in C++ modules or Lua scripts—both with downsides. One of our design goals with Istio was to bring ease of extensibility to allow an ecosystem of policy, telemetry, and logging systems. We did this with a control plane component and out-of-process adapters that could be written in any language, but this approach introduced additional network hops and latency.

This is where Wasm comes in. Wasm is a binary instruction format, compilable from over 30 languages, with a runtime to execute it in a sandboxed environment. Already embedded in all major browsers and with a W3C working group defining the standards, we are now bringing it server-side via Envoy. It allows adding functionality to the Envoy proxy without recompiling it, without forking, and without difficult rollouts. Istio can distribute extensions to proxies and load them without even restarting. This really brings together the best of both worlds in terms of extensibility—choice of language and great performance.

“I am extremely excited to see Wasm support land in Envoy; this is the future of Envoy extensibility, full stop. Envoy’s Wasm support coupled with a community driven hub will unlock an incredible amount of innovation in the networking space across both service mesh and API gateway use cases. I can’t wait to see what the community builds moving forward.” – Matt Klein, Envoy creator

To make sure that developing Wasm extensions is a great experience, our partner has been working hard on creating a great developer experience. recently announced WebAssembly Hub, a service for building, sharing, discovering and deploying Wasm extensions. With the WebAssembly Hub, Wasm extensions are as easy to manage, install and run as containers.

“We are committed to creating the most user friendly developer experience for service mesh. Like Docker did for containers, our goal is to simplify the consumption of WebAssembly extensions, which is the ‘why' behind WebAssembly Hub. By working with Google and the Istio open source community, we are able to simplify the experience of creating, sharing and deploying WebAssembly extensions to Envoy proxy and Istio, to bring the power of WebAssembly to more languages, and to enable a broader set of developers to innovate on service mesh." said Idit Levine, CEO and Founder,

One major retailer is looking to use Wasm to integrate with their policy system as they standardize use of Envoy—at the edge, as a sidecar, and even in their stores. The ability to roll out a policy change that is enforced everywhere they serve traffic, all with a great developer experience, makes Wasm a very attractive option for them.

By Dan Ciruli, Istio