consul: correctly interpret missing consul checks as unhealthy #15822
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This PR fixes a bug where Nomad assumed any registered Checks would exist in the service registration coming back from Consul. In some cases, the Consul may be slow in processing the check registration, and the response object would not contain checks. Nomad would then scan the empty response looking for Checks with failing health status, finding none, and then marking a task/alloc as healthy. In reality, we must always use Nomad's view of what checks should exist as the source of truth, and compare that with the response Consul gives us, making sure they match, before scanning the Consul response for failing check statuses. Fixes #15536
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lgfa29
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Jan 19, 2023
client/allochealth/tracker.go
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| expChecks := set.New[string](10) | ||
| expCount := 0 | ||
| regChecks := set.New[string](10) | ||
| regCount := 0 | ||
| for _, service := range services { | ||
| for _, check := range service.Checks { | ||
| expChecks.Insert(check.Name) | ||
| expCount++ | ||
| } | ||
| } | ||
| for _, task := range registrations.Tasks { | ||
| for _, service := range task.Services { | ||
| for _, check := range service.Checks { | ||
| regChecks.Insert(check.Name) | ||
| regCount++ | ||
| } | ||
| } | ||
| } | ||
| if expCount != regCount { | ||
| return false | ||
| } | ||
| if !expChecks.Equal(regChecks) { | ||
| return false | ||
| } |
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Minor nit-picking, but do we need a set and counter here? I think using a map[service name]: count would be enough and maybe easier to read?
gulducat
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Jan 19, 2023
| } | ||
| // scan for missing or unhealthy consul checks | ||
| if !evaluateConsulChecks(t.tg, allocReg) { | ||
| passed = false |
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Is it meaningful that t.setCheckHealth(false) is no longer called alongside this bool being set? I see that it is called elsewhere, but haven't chased down the potential implications of its removal here.
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Ah good catch, and I believe this is important in the edge case where
- checks become healthy
- tasks become healthy
- start minimum healthy time
- checks become unhealthy
- minimum healthy time ends <- we never updated check status to unhealthy, so we'll incorrectly report they are healthy
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Added this back in, and also added TestTracker_ConsulChecks_HealthToUnhealthy to cover the case where health checks transition from healthy to unhealthy during the minimum health period.
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This PR fixes a bug where Nomad assumed any registered Checks would exist
in the service registration coming back from Consul. In some cases, the
Consul may be slow in processing the check registration, and the response
object would not contain checks. Nomad would then scan the empty response
looking for Checks with failing health status, finding none, and then
marking a task/alloc as healthy.
In reality, we must always use Nomad's view of what checks should exist as
the source of truth, and compare that with the response Consul gives us,
making sure they match, before scanning the Consul response for failing
check statuses.
Fixes #15536