envoyproxy/envoy

Repeated on-demand vhds updates unsubscribe from previously resolved vhosts

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#12,158 opened on Jul 17, 2020

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area/xdsbughelp wanted

Description

Description: If a vhost named "foo.com" has been previously resolved, an attempt to resolve "bar.com" will result in "foo.com" vhost being unsubscribed from, and all updates for it lost.

This is due to how GrpcMuxWatch::update is implemented -- it expects a list of resource names that should be watched. The resources which names are not in the list will be unsubscribed from.

edit: not an issue for NewGrpcMuxImpl::addWatch

Contributor guide

Tech stack
cppgrpc
Domain
backendinfrastructure
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
4
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-2 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
C++ knowledgeEnvoy architecturegRPC concepts
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
25
Research direction
Examine the implementation of GrpcMuxWatch::update in the Envoy source code (likely under source/common/grpc/). The bug is that when a new vhost is resolved, the function unsubscribes from previously resolved vhosts because it expects a list of resource names to watch. The fix should ensure that previous subscriptions are retained. Look at the comments in the issue for any suggested approach or related PRs.
Repeated on-demand vhds updates unsubscribe from previously resolved vhosts · envoyproxy/envoy#12158 | Good First Issue