Bug 1811198

Summary:	/readyz should start reporting failure on shutdown initiation
Product:	OpenShift Container Platform	Reporter:	Abu Kashem <akashem>
Component:	kube-apiserver	Assignee:	Abu Kashem <akashem>
Status:	CLOSED ERRATA	QA Contact:	Ke Wang <kewang>
Severity:	high	Docs Contact:
Priority:	unspecified
Version:	4.4	CC:	aos-bugs, mfojtik, sttts, xxia
Target Milestone:	---
Target Release:	4.4.0
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:
Fixed In Version:		Doc Type:	Release Note
Doc Text:	Fixed /readyz endpoint to return failure immediately when an API server is terminating.	Story Points:	---
Clone Of:	1811169
Clones:	1821493 (view as bug list)		Environment:
Last Closed:	2020-05-04 11:45:36 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:	1811169
Bug Blocks:	1811200, 1821493, 1821494, 1821495

Description Abu Kashem 2020-03-06 20:09:12 UTC

+++ This bug was initially created as a clone of Bug #1811169 +++

Description of problem:

Currently, /readyz starts reporting failure after ShutdownDelayDuration elapses. The load balancer(s) uses /readyz for health check and are not aware of the shutdown initiation until ShutdownDelayDuration elapses. This does not give the load balancer(s) enough time to detect and react to it.

We expect /readyz to start returning failure as soon as apiserver shutdown is initiated(SIGTERM received). This gives the load balancer a window (defined by ShutdownDelayDuration) to detect that /readyz is red and stop sending traffic to this server.


How reproducible:
Always


upstream PR: https://github.com/kubernetes/kubernetes/pull/88911

Comment 3 Ke Wang 2020-03-16 09:31:54 UTC

Verified with OCP build 4.4.0-0.nightly-2020-03-15-215151, detail see below,

- in one terminal:
  - exec into kube-apiserver pod of master 0
    $ oc rsh -n openshift-kube-apiserver kube-apiserver-keosp1641-wq2sw-master-0
  - execute in pod terminal: 
    sh-4.2# while true; do curl -k https://localhost:6443/readyz; done
    okokokokokok ...

- in other terminal:
$ oc debug node/keosp1641-wq2sw-master-0
Starting pod/keosp1641-wq2sw-master-0-debug ...
To use host binaries, run `chroot /host`
Pod IP: 192.168.0.30
If you don't see a command prompt, try pressing enter.
sh-4.2# chroot /host
sh-4.4# bash
[root@keosp1641-wq2sw-master-0 /]# ps aux | grep " kube-apiserver "
root       55883 13.9  8.3 2782096 1365064 ?     Ssl  07:32  15:27 kube-apiserver --openshift-config=/etc/kubernetes/static-pod-resources/configmaps/config/config.yaml --advertise-address=192.168.0.30 -v=2
root      378139  0.0  0.0   9180  1080 pts/0    S+   09:23   0:00 grep --color=auto  kube-apiserver 

[root@keosp1641-wq2sw-master-0 /]# kill -INT 55883

- in first terminal we can see:

[+]ping ok
[+]log ok
[+]etcd ok
[+]poststarthook/quota.openshift.io-clusterquotamapping ok
[+]poststarthook/openshift.io-startkubeinformers ok
[+]poststarthook/openshift.io-StartOAuthInformers ok
[+]poststarthook/start-kube-apiserver-admission-initializer ok
[+]poststarthook/generic-apiserver-start-informers ok
[+]poststarthook/start-apiextensions-informers ok
[+]poststarthook/start-apiextensions-controllers ok
[+]poststarthook/crd-discovery-available ok
[+]poststarthook/crd-informer-synced ok
[+]poststarthook/bootstrap-controller ok
[+]poststarthook/rbac/bootstrap-roles ok
[+]poststarthook/scheduling/bootstrap-system-priority-classes ok
[+]poststarthook/start-cluster-authentication-info-controller ok
[+]poststarthook/aggregator-reload-proxy-client-cert ok
[+]poststarthook/start-kube-aggregator-informers ok
[+]poststarthook/apiservice-registration-controller ok
[+]poststarthook/apiservice-status-available-controller ok
[+]poststarthook/apiservice-wait-for-first-sync ok
[+]poststarthook/kube-apiserver-autoregistration ok
[+]autoregister-completion ok
[+]poststarthook/apiservice-openapi-controller ok
[-]shutdown failed: reason withheld
healthz check failed


The endpoint of readyz will start returning failure as soon as apiserver shutdown is initiated.

Comment 5 errata-xmlrpc 2020-05-04 11:45:36 UTC

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHBA-2020:0581