envoyproxy/envoy

When would a connection persist through a filter chain change?

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#14,967 opened on Feb 6, 2021

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Description

Title: When would a connection persist through a filter chain change?

Description:

Hi Envoy devs, apologies if this sounds an uninformed question. Doc [1] says that network filter changes will result in connection draining, and I do see that happen for network filter changes. But it seems that route changes via RDS in HTTP connection manager doesn't drain connections. So I'm wondering what is the logic under the hood: Are all http level config changes eligible to escape draining? Or is it because the protobuf message happen to be the same in the RDS case? So if ECDS is specified [2] would the connection also survive, even though ECDS may push new configs? Thanks!

Relevant Links:

[1] https://www.envoyproxy.io/docs/envoy/latest/intro/arch_overview/listeners/network_filter_chain#filter-chain-only-update [2] https://www.envoyproxy.io/docs/envoy/latest/api-v3/extensions/filters/network/http_connection_manager/v3/http_connection_manager.proto#envoy-v3-api-field-extensions-filters-network-http-connection-manager-v3-httpfilter-config-discovery

Contributor guide

Research direction
Examine the source code for HttpConnectionManager to understand how RDS updates avoid draining, and compare with network filter changes. Trace the logic in listener/filter chain updates.
Tech stack
cpp
Domain
backendinfrastructure
Issue type
Research
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
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Half day
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Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
C++Envoy proxy
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
55