Bug 1974183 - PodDisruptionBudgetAtLimit alert is fired in OVN SNO cluster
Summary: PodDisruptionBudgetAtLimit alert is fired in OVN SNO cluster
Keywords:
Status: CLOSED DUPLICATE of bug 2037721
Alias: None
Product: OpenShift Container Platform
Classification: Red Hat
Component: Networking
Version: 4.8
Hardware: Unspecified
OS: Unspecified
medium
medium
Target Milestone: ---
: ---
Assignee: Ben Pickard
QA Contact: Anurag saxena
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2021-06-21 05:50 UTC by Junqi Zhao
Modified: 2022-02-15 16:38 UTC (History)
2 users (show)

Fixed In Version:
Doc Type: If docs needed, set a value
Doc Text:
Clone Of:
Environment:
Last Closed: 2022-02-15 16:38:15 UTC
Target Upstream Version:
Embargoed:


Attachments (Terms of Use)
PodDisruptionBudgetAtLimit alert (79.48 KB, image/png)
2021-06-21 05:50 UTC, Junqi Zhao
no flags Details

Description Junqi Zhao 2021-06-21 05:50:07 UTC
Created attachment 1792596 [details]
PodDisruptionBudgetAtLimit alert

Description of problem:
OVN SNO cluster, PodDisruptionBudgetAtLimit alert is fired for openshift-ovn-kubernetes
# oc get node
NAME                                                STATUS   ROLES           AGE     VERSION
master-00.***.qe.devcluster.openshift.com   Ready    master,worker   3h11m   v1.21.0-rc.0+120883f

# oc get network/cluster -oyaml
.........
spec:
  clusterNetwork:
  - cidr: 10.128.0.0/14
    hostPrefix: 23
  externalIP:
    policy: {}
  networkType: OVNKubernetes
.........
alert detail
.........
alert: PodDisruptionBudgetAtLimit
expr: max by(namespace, poddisruptionbudget) (kube_poddisruptionbudget_status_current_healthy == kube_poddisruptionbudget_status_desired_healthy)
for: 1h
labels:
  severity: warning
annotations:
  message: The pod disruption budget is preventing further disruption to pods because it is at the minimum allowed level.
.........

search in prometheus
max by(namespace, poddisruptionbudget) (kube_poddisruptionbudget_status_current_healthy == kube_poddisruptionbudget_status_desired_healthy)
result is
{namespace="openshift-ovn-kubernetes", poddisruptionbudget="ovn-raft-quorum-guard"}

# oc -n openshift-ovn-kubernetes get PodDisruptionBudget
NAME                    MIN AVAILABLE   MAX UNAVAILABLE   ALLOWED DISRUPTIONS   AGE
ovn-raft-quorum-guard   1               N/A               0                     172m

maybe should not have PodDisruptionBudget for openshift-ovn-kubernetes in SNO cluster

Version-Release number of selected component (if applicable):
4.8.0-0.nightly-2021-06-16-020345

How reproducible:
always

Steps to Reproduce:
1. see the description
2.
3.

Actual results:


Expected results:


Additional info:

Comment 2 Patrick Strick 2022-01-21 01:22:30 UTC
SNO is GA now in 4.9 [1] and this still occurs when OVN-kubernetes is used. Also, the documentation for SNO uses OVNKubernetes in the example install config [2] which means customers are even more likely to get these alerts. Reopening per request.

[1] https://www.redhat.com/en/blog/meet-single-node-openshift-our-smallest-openshift-footprint-edge-architectures
[2] Step 6 at https://docs.openshift.com/container-platform/4.9/installing/installing_sno/install-sno-installing-sno.html#generating-the-discovery-iso-manually_install-sno-installing-sno-with-the-assisted-installer

Comment 3 Junqi Zhao 2022-01-21 06:28:13 UTC
(In reply to Patrick Strick from comment #2)
> SNO is GA now in 4.9 [1] and this still occurs when OVN-kubernetes is used.
> Also, the documentation for SNO uses OVNKubernetes in the example install
> config [2] which means customers are even more likely to get these alerts.
> Reopening per request.
> 
> [1]
> https://www.redhat.com/en/blog/meet-single-node-openshift-our-smallest-
> openshift-footprint-edge-architectures
> [2] Step 6 at
> https://docs.openshift.com/container-platform/4.9/installing/installing_sno/
> install-sno-installing-sno.html#generating-the-discovery-iso-
> manually_install-sno-installing-sno-with-the-assisted-installer

FYI, same issue happen in 4.10 SNO cluster, see bug 2037721, among the many PDBs, only openshift-ovn-kubernetes fires PodDisruptionBudgetAtLimit alert


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