[release-2.0] Propagate resource version when sharded #1402
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Addresses a bug that causes a gap between `list` and `watch` when kube-state-metrics is sharded (fix for kubernetes#694) Kube-state-metrics does a `list` and then enters a `watch` loop. The intention is to `watch` **all** events after the initial list. The k8s API takes an optional `resource version` parameter which is returned as part of the `list` call and can be forwarded to the `watch` call, in order to fetch all events after the initial `list`. In its sharded version, kube-state-metrics intercepts the returned `list` in order to filter out the events for other shards. It reconstructs the response, but it does not propagate the `resource version` to the modified response. The subsequent `watch` call does not refer to a resource version. When `watch` is called without a `resource version`, it will provide a view consistent with the **most recent** resource version of the `watch` call, missing the events between the `resource version` at `list` call and the most recent one. The k8s documentation captures this as follows: _Get State and Start at Most Recent: Start a watch at the most recent resource version, which must be consistent (i.e. served from etcd via a quorum read). To establish initial state, the watch begins with synthetic "Added" events of all resources instances that exist at the starting resource version. All following watch events are for all changes that occurred after the resource version the watch started at._ Testing: Reproduced the original bug report deterministically by introducing an artificial delay (120s) in list, prior to returning the response, and terminating some pods. Unless the bug is fix, the terminated pods continue to be reported as running by kube-state-metrics (cherry picked from commit c1842eb)
(cherry picked from commit e1327ca)
(cherry picked from commit 3e6cd66)
(cherry picked from commit 8b2ef33)
(cherry picked from commit 6ee0f92)
(cherry picked from commit d40eb33)
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looks like we accidentally merged it into /lgtm |
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[APPROVALNOTIFIER] This PR is APPROVED This pull-request has been approved by: brancz, tariq1890 The full list of commands accepted by this bot can be found here. The pull request process is described here
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Cherrypick of PR commits #1390
cc @brancz