spec VS proxy-wasm-go-sdk

OWASP also provides Coraza, a port of ModSecurity available as a Go library. Coraza Proxy Wasm is built on top of Coraza and implements the proxy-wasm ABI, which specifies a set of Wasm interfaces for proxies. Finally, Apache APISIX offers proxy-wasm integration.

APISIX supports Wasm through the WebAssembly for Proxies (proxy-wasm) specification. APISIX is a host environment that implements the specification, and developers can use the SDKs available in multiple languages to create plugins.

Hi HN!

For the past few weeks we've been working on Proximal - a workflow engine that lets you quickly iterate on WebAssembly extensions for Envoy Proxy[0] (or other proxies) right on your local machine: https://github.com/apoxy-dev/proximal

This work is based on Proxy-WASM[1] extension ABI for Envoy (and other proxies like APISIX and Mosn[2]) which allows you to execute WebAssembly code on every API request a la Cloudflare Workers. As part of our wider effort at https://apoxy.dev to improve API glue code we built an experimentation / development platform and hope you will find it useful!

On the technical side this project packs Envoy itself, Envoy controller, REST API (for controlling the controller =)), React SPA, and Temporal server/worker (for orchestration) - all baked into a single Go binary. You can find more on architecture and limitations in the repository README[4].

This project is pretty early stage and we would appreciate community feedback!

Previous HN discussions on this topic:

* https://news.ycombinator.com/item?id=36113542

* https://news.ycombinator.com/item?id=22582276

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[0] https://www.envoyproxy.io/

[1] https://github.com/proxy-wasm/spec/blob/master/docs/WebAssem...

[2] https://apisix.apache.org/ https://mosn.io/

[3] https://github.com/apoxy-dev/proximal/blob/main/README.md#ar...

Wasm Labs dev here :)

In mod_wasm, there are some differences with a pure CGI implementation. When Apache boots, it loads the configuration and initializes the WasmVM. When a new HTTP request arrives, the VM is ready so you don't need to initialize a different process to manage it.

You still need to process the request and pass the data to the Wasm module. This step is done via STDIN through the WebAssembly System Interface (WASI) implementation [0]. The same happens in the opposite direction, as the module returns the data via STDOUT.

So, the CGI pattern is still there, but it doesn't require new processes and all the code runs in a sandbox.

However this is not the only way you can run a Wasm module. In this specific case, we use CGI via WASI. In other cases, you may compile a module to fulfill a specific API, like ProxyWasm [1] to create HTTP filters for proxies like Envoy.

- [0] https://wasi.dev/

- [1] https://github.com/proxy-wasm/spec

proxy-wasm spec

The team considered to solve the issue with C++ extensions, but discarded this approach as neither APIs nor ABIs were stable. Instead, they chose to provide a stable WebAssembly-based ABI. If you're interested in a more detailed background, you can read the whole piece on GitHub.

// references: // https://github.com/tetratelabs/proxy-wasm-go-sdk/tree/main/examples // https://github.com/apache/apisix/blob/master/t/wasm/ package main import ( "github.com/tetratelabs/proxy-wasm-go-sdk/proxywasm" "github.com/tetratelabs/proxy-wasm-go-sdk/proxywasm/types" "github.com/valyala/fastjson" ) func main() { proxywasm.SetVMContext(&vmContext{}) } // each plugin has its own VMContext. // it is responsible for creating multiple PluginContexts for each route. type vmContext struct { types.DefaultVMContext } // each route has its own PluginContext. // it corresponds to one instance of the plugin. func (*vmContext) NewPluginContext(contextID uint32) types.PluginContext { return &pluginContext{} } type header struct { Name string Value string } type pluginContext struct { types.DefaultPluginContext Headers []header } func (ctx *pluginContext) OnPluginStart(pluginConfigurationSize int) types.OnPluginStartStatus { data, err := proxywasm.GetPluginConfiguration() if err != nil { proxywasm.LogErrorf("error reading plugin configuration: %v", err) return types.OnPluginStartStatusFailed } var p fastjson.Parser v, err := p.ParseBytes(data) if err != nil { proxywasm.LogErrorf("error decoding plugin configuration: %v", err) return types.OnPluginStartStatusFailed } headers := v.GetArray("headers") ctx.Headers = make([]header, len(headers)) for i, hdr := range headers { ctx.Headers[i] = header{ Name: string(hdr.GetStringBytes("name")), Value: string(hdr.GetStringBytes("value")), } } return types.OnPluginStartStatusOK } // each HTTP request to a route has its own HTTPContext func (ctx *pluginContext) NewHttpContext(contextID uint32) types.HttpContext { return &httpContext{parent: ctx} } type httpContext struct { types.DefaultHttpContext parent *pluginContext } func (ctx *httpContext) OnHttpResponseHeaders(numHeaders int, endOfStream bool) types.Action { plugin := ctx.parent for _, hdr := range plugin.Headers { proxywasm.ReplaceHttpResponseHeader(hdr.Name, hdr.Value) } return types.ActionContinue }

Go (TinyGo) SDK