API Aggregation with Envoy & WASM

I'll try to build a simple API aggregation plugin for Envoy using WebAssembly (Wasm) as the extension mechanism.

• Live stream: https://www.youtube.com/watch?v=Tbdj5Sw6HI0

What are we building?

If I make a request to /hello on the proxy, I want the proxy (or the extension) to make a call to:

• GET host1 /one
• GET host2 /two

Combine (or aggregate) the responses from those two endpoints and then return that response.

We make request to /hello --> Proxy makes requests to /one and /two --> Proxy aggregates the responses and returns it to the client.

GET /hello --> [{ "value": "one" }, { "value": "two"}]
/one --> { "value": "one" }
/two --> { "value": "two" }

Configuration

[{
    "path": "/",
    "upstreams": [
        {
            "clusterName": "httpbin",
            "path": "/ip"
        },
        {
            "clusterName": "httpbin",
            "path": "/headers"
        }
    ],
}]

TODOs

• Scaffold the basic Wasm extension project
• Create (aka re-use) the Makefile for building the Wasm extension
• Implement calling multiple upstream services from the Wasm extension & aggregating the responses in some way
• Make the extension configurable with the upstream services to call and the aggregation strategy
• Add authority and method to the configuration
• Properly aggregate the responses