When a Connect service is registered with Consul, Nomad includes the nested
`Connect.SidecarService` field that includes health checks for the Envoy
proxy. Because these are not part of the job spec, the alloc health tracker
created by `health_hook` doesn't know to read the value of these checks.
In many circumstances this won't be noticed, but if the Envoy health check
happens to take longer than the `update.min_healthy_time` (perhaps because it's
been set low), it's possible for a deployment to progress too early such that
there will briefly be no healthy instances of the service available in Consul.
Update the Consul service client to find the nested sidecar service in the
service catalog and attach it to the results provided to the tracker. The
tracker can then check the sidecar health checks.
Fixes: https://github.com/hashicorp/nomad/issues/19269
* consul: correctly understand missing consul checks as unhealthy
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
* consul: minor CR refactor using maps not sets
* consul: observe transition from healthy to unhealthy checks
* consul: spell healthy correctly
This PR adds support for specifying checks in services registered to
the built-in nomad service provider.
Currently only HTTP and TCP checks are supported, though more types
could be added later.
This commit performs refactoring to pull out common service
registration objects into a new `client/serviceregistration`
package. This new package will form the base point for all
client specific service registration functionality.
The Consul specific implementation is not moved as it also
includes non-service registration implementations; this reduces
the blast radius of the changes as well.
Update the logic in the Nomad client's alloc health tracker which
erroneously marks existing healthy allocations with dead poststart ephemeral
tasks as unhealthy even if they were already successful during a previous
deployment.
Allow for readiness type checks by configuring nomad to ignore warnings
or errors reported by a service check. This allows the deployment to
progress and while Consul handles introducing the sercive into a
resource pool once the check passes.
* investigating where to ignore poststop task in alloc health tracker
* ignore poststop when setting latest start time for allocation
* clean up logic
* lifecycle: isolate mocks for poststop deployment test
* lifecycle: update comments in tracker
Co-authored-by: Jasmine Dahilig <jasmine@dahilig.com>
Fixes a bug where an allocation is considered healthy if some of the
tasks are being restarted and as such, their checks aren't tracked by
consul agent client.
Here, we fix the immediate case by ensuring that an alloc is healthy
only if tasks are running and the registered checks at the time are
healthy.
Previously, health tracker tracked task "health" independently from
checks and leads to problems when a task restarts. Consider the
following series of events:
1. all tasks start running -> `tracker.tasksHealthy` is true
2. one task has unhealthy checks and get restarted
3. remaining checks are healthy -> `tracker.checksHealthy` is true
4. propagate health status now that `tracker.tasksHealthy` and
`tracker.checksHealthy`.
This change ensures that we accurately use the latest status of tasks
and checks regardless of their status changes.
Also, ensures that we only consider check health after tasks are
considered healthy, otherwise we risk trusting incomplete checks.
This approach accomodates task dependencies well. Service jobs can have
prestart short-lived tasks that will terminate before main process runs.
These dead tasks that complete successfully will not negate health
status.
