OCPEDGE-2810: add CIB-backed fail-count fields to PacemakerClusterResourceStatus - #3042

Actionable comments posted: 1

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Inline comments:
In `@etcd/v1/types_pacemakercluster.go`:
- Line 742: Change the alertAgentScripts fields in the PacemakerCluster status
types for both API versions to pointers to slices, preserving explicit empty
lists while allowing nil to represent uncollected status. Do not reject or
otherwise alter valid zero-item lists.

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Actionable comments posted: 1

• 🪄 Fix CodeRabbit comments on this PR

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only still-valid issues, skip the rest with a brief reason, keep changes
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Inline comments:
In `@etcd/v1/types_pacemakercluster.go`:
- Line 729: Add API integration coverage for DualReplica status in both etcd/v1
and etcd/v1alpha1, including omitted failCount, migrationThreshold,
lastStopTime, lastStartTime, and lastFailureTime, plus zero/nonzero counter
values and valid RFC3339 timestamps. Extend the existing DualReplica fixtures or
status cases to verify optional-field serialization and API validation without
changing the generated types.

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Thank you for providing a dense overview in the description. Here's my commentary on each new field:

PacemakerCluster
└── status (PacemakerClusterStatus)
    ├── conditions[]
    │   └── FencingEnabled      ← NEW (#1) — tracks stonith-enabled property

FencingEnabled provides an immediate siren when the cluster is an unsafe state. It's worth bubbling up to this level as well as collecting it into the aggregate cluster healthy condition.

    └── nodes[] (PacemakerClusterNodeStatus)
        ├── lastFenceEvent       ← NEW (#2) — most recent fence event targeting this node
        │   ├── action           (reboot | off | on)
        │   ├── status           (success | failed | pending)
        │   ├── delegate         (which node executed the fence op)
        │   ├── client           (crmd | stonith_admin)
        │   ├── origin           (node that originated the request)
        │   ├── lastUpdated      (CIB timestamp, always present)
        │   └── completedTime    (nil while pending)

LastFenceEvent is interesting. One thing I try to think about with APIs is - how is the user supposed to act upon the information being provided? In this case, a user that is interested in tracking each fencing event is better off going straight to pcs or to collect each fencing event as they are reported in events.

This is more persistent than events, but I'm struggling to come up with a use case where I would want access to this information in the cluster in this limited form.

I feel like the metrics an admin cares about are:

• Over the history of the cluster, how many fencing events have occured and when did they happen?
• Were there any failed fencing attempts. If so, why did they fail?

This extension solve neither of those completely. Both can only be fully answered directly through pcs today. At best, we can provide a reason for why the last fencing event that we saw failed, which could be useful but the fact that it failed/is unhealthy is already raised through the existing conditions for the fencingAgent. So maybe our strongest argument for this is that this could explain why it failed sometimes?

Also, won't delegate and origin always be set to the same value? In TNF, the only node that can fence is the other is its peer - so the delegate node for sure will always be the peer. I'm less sure about origin, but I'm once again asking - what am I supposed to do with this information? Both fields seem unnecessary to me unless we have a concrete user story for when this information would help address administrator concern. The only node-related bit that matters as I understand it is which node is the target of the fencing event. Since the target is the node we're listing under, I don't see the value of these fields.

        ├── resources[] (PacemakerClusterResourceStatus)
        │   ├── failCount        ← NEW (#3) — CIB fail-count for this resource
        │   ├── lastStopTime     ← NEW (#4) — last stop op timestamp
        │   ├── lastStartTime    ← NEW (#5) — last start op timestamp
        │   ├── migrationThreshold ← NEW (#6) — threshold before Pacemaker gives up
        │   └── lastFailureTime  ← NEW (#7) — most recent failure timestamp
        └── fencingAgents[] (PacemakerClusterFencingAgentStatus)
            ├── failCount        ← NEW (#8) — CIB fail-count for this fence agent
            ├── migrationThreshold ← NEW (#9) — threshold for this fence agent
            └── lastFailureTime  ← NEW (#10) — most recent fence agent failure

Grouping my commentary for these together:

failCount and migrationThreshold only seem relevant in a future update where we make the migrationThreshold field user-configurable. Without that, this information isn't meaningfully actionable. If we want to add these, we should provide one or more user-stories as justification for how a cluster admin (PHC) would use this information to take action on something in the cluster.

lastStartTime, lastStopTime, lastFailureTime: What is the user supposed to do with this information? To me, these feels like partial record that are insufficient to recreate what happened in pacemaker to create a given state. That said, I could see a world where we raise a PHC unhealthy status if the lastStartTime >= X minutes AND the resource is unavailable. That being said, the resource being unavailable is already sufficient to establish that something is broken, so you haven't gained any actionable information. Do we have use cases for when these would be helpful?

Final Notes

My overall feedback is that we need to justify why we're adding these and how they should be used. Everything that exists in the API today exists specifically to expose known unhealthy state to the user via PacemakerHealthCheck.

Many of the proposed changes don't inherently track failed state. So it's unclear to me how they're expected to be used, and thus becomes harder to justify added them. Adding them has few costs:

1. We need to support them for the lifecycle of the API (i.e. forever)
2. We have less flexibility for how to expose similar or the same information in the future if we need to introduce a way to get access to this information that are directly linked to concrete user-stories. (E.g. we will want to expose fail-count and threshold if we ever make them configurable, and may want to make the bits we already document as configurable controllable via this API).

Final Final Note

One last thing to consider. PacemakerCluster depends on API availability, so any information that it gathers related to fencing or a failed resource (i.e. etcd/kubelet, are all but guaranteed to be stale by the time they're bubbled up. One of the consequences of exposing things like lastFailedTime is that users might think this is a good way of monitoring when fencing actions are happening in real time - but by definition - these values won't appear in PacemakerCluster until after fencing has occurred, quorum is reestablished, and the status-collector pod (which is only best-effort on the minute) is scheduled and executed on a node.

In the end, whatever user stories we provide also need to account for the fact that we're raising this information - in the best case scenario - as soon as the cluster recovers if the status collector is scheduled immediately.

In theory, you could catch a fencing event before it triggers, but the odds of that happening seem slim since the fencing event would need to be recorded but not yet started at the exact moment when the status collector job runs - a window for a race we will almost always lose.