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vtorc: require topo for Healthy: true in /debug/health #17129

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vtorc: require topo for Healthy: true in /debug/health #17129

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@timvaillancourt timvaillancourt commented Oct 31, 2024 •
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Description

This PR addresses #17121 by requiring that we're able to reach the topology at least once (even if it's just empty) before returning Healthy: true in /debug/health. Today a VTOrc is considered healthy purely if it can write to it's own database

This is to prevent a vtorc deployment with a broken topo config to be seen as healthy, which in Kube can cause a bad config deploy to rollout to all nodes when it could fail on the first that it breaks

Also some error logging was consolidated so we don't log the topo failure multiple times for the same call (see below)

Example with this change:

tim@Tims-MacBook-Pro vitess % ./bin/vtorc --topo_global_server_address http://nowhere --topo_global_root /vitess --topo_implementation consul --config-name '' --port 15000
E1031 23:53:46.669158   54870 tablet_discovery.go:74] failed to initialize topo information: Get "http://nowhere/v1/kv/vitess/keyspaces/?keys=": dial tcp: lookup nowhere: no such host
E1031 23:54:01.675685   54870 vtorc.go:337] failed to refresh topo information: Get "http://nowhere/v1/kv/vitess/keyspaces/?keys=": dial tcp: lookup nowhere: no such host
E1031 23:54:16.677020   54870 vtorc.go:337] failed to refresh topo information: Get "http://nowhere/v1/kv/vitess/keyspaces/?keys=": dial tcp: lookup nowhere: no such host

And in another shell:

tim@Tims-MacBook-Pro vitess % curl -s localhost:15000/debug/health | jq .
{
  "Healthy": false,
  "LastReported": "2024-10-31T23:28:06.315105+01:00"
}

(previous to this PR "Healthy": true was returned)

Backport reason

I think this should be backported to prevent users from the scenario described above. This issue could lead to a user believing a VTOrc deployment is healthy when it's actually unable to load anything from the topo

Related Issue(s)

Resolves #17121

Checklist

  • "Backport to:" labels have been added if this change should be back-ported to release branches
  • If this change is to be back-ported to previous releases, a justification is included in the PR description
  • Tests were added or are not required
  • Did the new or modified tests pass consistently locally and on CI?
  • Documentation was added or is not required

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vitess-bot bot commented Oct 31, 2024

Review Checklist

Hello reviewers! 👋 Please follow this checklist when reviewing this Pull Request.

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@vitess-bot vitess-bot bot added NeedsBackportReason If backport labels have been applied to a PR, a justification is required NeedsDescriptionUpdate The description is not clear or comprehensive enough, and needs work NeedsIssue A linked issue is missing for this Pull Request NeedsWebsiteDocsUpdate What it says labels Oct 31, 2024
@timvaillancourt timvaillancourt added Type: Bug Type: Enhancement Logical improvement (somewhere between a bug and feature) Component: VTorc Vitess Orchestrator integration labels Oct 31, 2024
@github-actions github-actions bot added this to the v22.0.0 milestone Oct 31, 2024
@timvaillancourt timvaillancourt removed NeedsDescriptionUpdate The description is not clear or comprehensive enough, and needs work NeedsWebsiteDocsUpdate What it says NeedsIssue A linked issue is missing for this Pull Request NeedsBackportReason If backport labels have been applied to a PR, a justification is required labels Oct 31, 2024
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codecov bot commented Oct 31, 2024 •
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Codecov Report

Attention: Patch coverage is 2.32558% with 42 lines in your changes missing coverage. Please review.

Project coverage is 67.40%. Comparing base (f6067e0) to head (bfb151f).
Report is 2 commits behind head on main.

Files with missing lines Patch % Lines
go/vt/vtorc/logic/vtorc.go 0.00% 20 Missing ⚠️
go/vt/vtorc/logic/tablet_discovery.go 0.00% 15 Missing ⚠️
go/vt/vtorc/logic/keyspace_shard_discovery.go 0.00% 7 Missing ⚠️
Additional details and impacted files 
@@           Coverage Diff           @@
##             main   #17129   +/-   ##
=======================================
  Coverage   67.40%   67.40%           
=======================================
  Files        1570     1570           
  Lines      252903   252909    +6     
=======================================
+ Hits       170460   170465    +5     
- Misses      82443    82444    +1

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

@timvaillancourt timvaillancourt marked this pull request as ready for review November 1, 2024 00:03
@timvaillancourt timvaillancourt added Backport to: release-19.0 Needs to be back ported to release-19.0 Backport to: release-20.0 Needs to be backport to release-20.0 Backport to: release-21.0 Needs to be backport to release-21.0 labels Nov 4, 2024
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Added backport labels because I think it's unsafe for VTOrc to report it is healthy when it cannot see the topo. This could lead to outages if a vtorc config is invalid and deployed for some time

This was referenced Nov 5, 2024
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shlomi-noach
shlomi-noach reviewed Nov 13, 2024
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The change makes sense to me. I do have one question inline.

Re: backports, deferring to @deepthi

go/vt/vtorc/logic/tablet_discovery.go
// We refresh all information from the topo once before we start the ticks to do it on a timer.
populateAllInformation()
// We refresh all information from the topo once before we start the ticks to do
// it on a timer. We can wait forever (context.Background()) for this call.
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Can you please explain how do you mean "We can wait forever (context.Background()) for this call."?

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@timvaillancourt timvaillancourt Nov 13, 2024 •
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@shlomi-noach this comment is confusing, yeah

What I intended with adding the context.Context is to prevent ticks from overlapping here (currently no timeout)

This area of the code is ran once before the ticker starts at vtorc init time, so I figured waiting forever had no risk. Adding a timeout here as well wouldn't hurt either I suppose

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is to prevent ticks from overlapping here

Sorry, not "overlapping" per se, but one loop iteration stalling things

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I do prefer that we have some form of timeout -- let's say this errors and we cannot connect to topo -- is there going to be some retry? If yes, let's timeout. If not, let's consider our options.

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@shlomi-noach makes sense, I've updated to use a timeout == topo.RemoteOperationTimeout 👍

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@deepthi deepthi Awaiting requested review from deepthi deepthi is a code owner

@GuptaManan100 GuptaManan100 Awaiting requested review from GuptaManan100 GuptaManan100 is a code owner

@shlomi-noach shlomi-noach Awaiting requested review from shlomi-noach shlomi-noach is a code owner

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Successfully merging this pull request may close these issues.

Bug Report: /debug/health in vtorc returns false healthy state
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@timvaillancourt @shlomi-noach