Red Hat Summit1.21. Extensions
You can use WebAssembly extensions to add new features directly into the Red Hat OpenShift Service Mesh proxies. This lets you move even more common functionality out of your applications, and implement them in a single language that compiles to WebAssembly bytecode.
WebAssembly extensions are not supported on IBM Z and IBM Power.
1.21.1. WebAssembly modules overview
WebAssembly modules can be run on many platforms, including proxies, and have broad language support, fast execution, and a sandboxed-by-default security model.
Red Hat OpenShift Service Mesh extensions are Envoy HTTP Filters, giving them a wide range of capabilities:
- Manipulating the body and headers of requests and responses.
- Out-of-band HTTP requests to services not in the request path, such as authentication or policy checking.
- Side-channel data storage and queues for filters to communicate with each other.
When creating new WebAssembly extensions, use the WasmPlugin API. The ServiceMeshExtension API was deprecated in Red Hat OpenShift Service Mesh version 2.2 and was removed in Red Hat OpenShift Service Mesh version 2.3.
There are two parts to writing a Red Hat OpenShift Service Mesh extension:
- You must write your extension using an SDK that exposes the proxy-wasm API and compile it to a WebAssembly module.
- You must then package the module into a container.
Supported languages
You can use any language that compiles to WebAssembly bytecode to write a Red Hat OpenShift Service Mesh extension, but the following languages have existing SDKs that expose the proxy-wasm API so that it can be consumed directly.
| Language | Maintainer | Repository |
|---|---|---|
| AssemblyScript | solo.io | |
| C++ | proxy-wasm team (Istio Community) | |
| Go | tetrate.io | |
| Rust | proxy-wasm team (Istio Community) |
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