Bug 1836016

Summary:	Azure UPI: Both Internal and External load balancers for kube-apiserver should use /readyz
Product:	OpenShift Container Platform	Reporter:	W. Trevor King <wking>
Component:	Installer	Assignee:	Etienne Simard <esimard>
Installer sub component:	openshift-installer	QA Contact:	Mike Gahagan <mgahagan>
Status:	CLOSED ERRATA	Docs Contact:
Severity:	medium
Priority:	high	CC:	adahiya, akashem, bleanhar, choag, esimard, ffranz, jminter, mgahagan, mjudeiki, wking, xxia
Version:	4.5	Keywords:	Upgrades
Target Milestone:	---
Target Release:	4.6.0
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:
Fixed In Version:		Doc Type:	Bug Fix
Doc Text:	Cause: Healthcheck probes not defined on Azure UPI deployed load balancers Consequence: Load balancers do not properly detect when an API endpoint is no longer available and may still direct traffic causing client failures. Fix: Added Healthcheck probes to Azure UPI deployed load balancers Result: Load balancers properly detect when API endpoints are not available and do not route traffic to offline nodes.	Story Points:	---
Clone Of:	1828382
Clones:	1872822 (view as bug list)		Environment:
Last Closed:	2020-10-27 15:59:41 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:
Bug Blocks:	1872822, 1873280, 1874582, 1880726

Description W. Trevor King 2020-05-14 23:42:02 UTC

+++ This bug was initially created as a clone of Bug #1828382 +++

Description of problem:
Load balancers (both internal and external) for kube-apiserver should use /readyz for back-end health check.

After scanning the github repo, we found the following platforms do not use /readyz for backend health check.

Azure: 
https://github.com/openshift/installer/blob/master/data/data/azure/vnet/internal-lb.tf#L138
https://github.com/openshift/installer/blob/master/data/data/azure/vnet/public-lb.tf#L164
https://github.com/openshift/installer/blob/master/upi/azure/03_infra.json#L101
https://github.com/openshift/installer/blob/master/upi/azure/03_infra.json#L184


VSphere: 
https://github.com/openshift/installer/blob/master/upi/vsphere/lb/haproxy.tmpl#L33


Please investigate the following, not sure if it needs to be addressed 
https://github.com/openshift/installer/blob/master/upi/aws/cloudformation/02_cluster_infra.yaml#L179

The above health checks use default TCP rule which breaks graceful termination. When the apiserver receives a KILL signal /readyz will start reporting failure. This gives the load balancer a chance to detect an instance that is rolling out and take appropriate action.    


We should use AWS lb rules as a reference for consistency - https://github.com/openshift/installer/blob/master/data/data/aws/vpc/master-elb.tf#L87

"health_check {
    healthy_threshold   = 2
    unhealthy_threshold = 2
    interval            = 10
    port                = 6443
    protocol            = "HTTPS"
    path                = "/readyz"
 }"



Version-Release number of the following components:
OpenShift 4.5. 

How reproducible:
Always

Steps to Reproduce:
1. Run an upgrade job on the specified infrastructure. 

You will see that the load balancer is sending request to an apiserver while it's down. 


Actual results:
An example: https://prow.svc.ci.openshift.org/view/gcs/origin-ci-test/logs/release-openshift-ocp-installer-e2e-azure-serial-4.4/1542

Apr 26 21:45:14.063: INFO: Unexpected error listing nodes: Get https://api.ci-op-hvqc8pgw-0ba00.ci.azure.devcluster.openshift.com:6443/api/v1/nodes?fieldSelector=spec.unschedulable%3Dfalse&resourceVersion=0: dial tcp 52.154.154.255:6443: connect: connection refused



Expected results:
The load balancer should identify the kube-apiserer instance that is being rolled out in time and forward requests to another instance that is serving. Ideally, we should not see any "dial tcp 52.154.154.255:6443: connect: connection refused" error while kube-apiserver is being rolled out.


Bug 1828382 handled installer-provisioned Azure.  This clone is for the user-provisioned Azure recommendations.  Dropping severity down to medium, because user-provisioned recommendations are suggesting approaches, not telling the user what they should be doing without thinking.

Comment 1 Abhinav Dahiya 2020-05-18 17:24:35 UTC

Won't be able to get to it this sprint.

Comment 3 John Hixson 2020-06-08 16:56:01 UTC

PR: https://github.com/openshift/installer/pull/3720

Comment 6 Mike Gahagan 2020-06-11 20:54:16 UTC

Confirmed both internal and external loadbalancers are using http/https and the /readyz endpoint in UPI Azure using 4.5.0-0.nightly-2020-06-10-224736

public lb:



    "name": "api-internal-probe",
    "numberOfProbes": 3,
    "port": 6443,
    "protocol": "Https",
    "provisioningState": "Succeeded",
    "requestPath": "/readyz",
    "resourceGroup": "esimardupi-4zmfb-rg",
    "type": "Microsoft.Network/loadBalancers/probes"

internal lb:


    "name": "api-internal-probe",
    "numberOfProbes": 3,
    "port": 6443,
    "protocol": "Https",
    "provisioningState": "Succeeded",
    "requestPath": "/readyz",
    "resourceGroup": "esimardupi-4zmfb-rg",
    "type": "Microsoft.Network/loadBalancers/probes"

Comment 7 Abhinav Dahiya 2020-08-24 16:50:48 UTC

*** Bug 1856729 has been marked as a duplicate of this bug. ***

Comment 9 errata-xmlrpc 2020-10-27 15:59:41 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 (OpenShift Container Platform 4.6 GA Images), 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-2020:4196