State and Future of EnvoyGateway Extension Points

[Xunzhuo]

Current State

In v0.4.0, eg introduces ExtensionManager, grpc based extension hooks, to dynamically modify xds resources generated by EG.

In v0.5.0, eg introduces EnvoyPatchPolicy, a CRD resource, to dynamically patch xds resource generated by EG.

In the two above approaches, the extension target is the whole xds resources. It unlocks the full power of xds for vendors/teams to extend EG abilities, which is powerful and flexible.

What`s More?

EnvoyProxy itself provides some extension http filters, which allows people dynamically extend envoyproxy without restarting it, like Lua, WASM and new introduced Go Extension Filter.

I propose EG to provide high level APIs(CRDs) to abstract these extension points. From my experience of using EnvoyFilter in istio, compared with the full xds patch/modify, these ways have more specific target scopes and easier to be control, which are safer , easier and less dangerous to be used.

ExtensionRef or PolicyAttachment ?

ExtensionRef can be used per-route-rule/per-backend, and PolicyAttachment can be used to whole Gateway/xRoute.

• WASMFilter or WASMExtensionPolicy CRD
• LuaFilter or LuaExtensionPolicy CRD
• GoFilter or GoExtensionPolicy CRD

[arkodg]

Im a +1 on this idea, it can be a safer, less scoped way than EnvoyPatchPolicy of extending EG

[denniskniep]

@zhaohuabing @arkodg is there already some progress on integrating GoLang Filters (HTTP, Network)

Envoy Docs:
https://www.envoyproxy.io/docs/envoy/latest/configuration/listeners/network_filters/golang_filter#config-network-filters-golang
https://www.envoyproxy.io/docs/envoy/latest/configuration/http/http_filters/golang_filter#config-http-filters-golang

Envoy Examples:
https://www.envoyproxy.io/docs/envoy/latest/start/sandboxes/golang-http
https://www.envoyproxy.io/docs/envoy/latest/start/sandboxes/golang-network

[zirain]

@denniskniep is it a part of envoy core? if not, maybe we should wait for it.

[denniskniep]

@zirain
code is located in /contrib/golang folder of envoy repo in main branch:
https://github.com/envoyproxy/envoy/tree/main/contrib/golang

Current status is alpha

see here and here

What do you mean exactly with envoy core?

BTW: Status of WASM Filter is also alpha see here

[zirain]

can you use these filter with envoyproxy/envoy:<version> image instead of envoyproxy/envoy:contrib-<version>?

[denniskniep]

yes, its only available within contrib image (api docs)

Is there any document in envoy where roadmap or plans for these graduation from contrib to core are listed ?