Roadmap for upstream filter from alpha to GA

[yuzisun]

Title: Roadmap for upstream filter to GA

Description:

The Upstream Filter (envoy.filters.http.upstream_filter) is currently marked as alpha, but it has become a critical dependency for the Envoy AI Gateway project and other advanced use cases.

The feature enables powerful post-router, pre-upstream HTTP filter processing, which is essential for implementing:
• External processing (ext_proc) logic after routing decisions
• AI workload orchestration (e.g., request transformation)
• Upstream authentication to cloud providers

Given its criticality for handling AI traffic, we ask for the roadmap for promoting the feature to GA.

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Any extra documentation required to understand the issue.

[yanavlasov]

The envoy.filters.http.upstream_filter filter had been used in production for a long time, so its alpha state no longer makes sense.

However it will not solve the issue of supporting other filters (such as ext_proc) in the upstream filter chain. Each one has to be looked at specifically.

[yanjunxiang-google]

Looking at source/extensions/extensions_metadata.yaml file, there are about 12 upstream HTTP filters so far. Two of them are marked as "status_upstream: stable": envoy.filters.http.upstream_codec, and envoy.filters.http.buffer. The rest are marked as "status_upstream: alpha". We can start by turning ext_proc into "status_upstream: stable".

[yuzisun]

Looking at source/extensions/extensions_metadata.yaml file, there are about 12 upstream HTTP filters so far. Two of them are marked as "status_upstream: stable": envoy.filters.http.upstream_codec, and envoy.filters.http.buffer. The rest are marked as "status_upstream: alpha". We can start by turning ext_proc into "status_upstream: stable".

Thanks! that would be helpful and is the major one we are using. Any work left to make it stable?

[yanjunxiang-google]

Yeah, there are some work left for ext_proc in upstream. I will update here once those are done.