Bug 1804574

Summary: Prometheus federation write is failing on a large scale cluster
Product: OpenShift Container Platform Reporter: Sergiusz Urbaniak <surbania>
Component: MonitoringAssignee: Sergiusz Urbaniak <surbania>
Status: CLOSED DUPLICATE QA Contact: Junqi Zhao <juzhao>
Severity: low Docs Contact:
Priority: unspecified    
Version: 4.3.0CC: alegrand, anpicker, erooth, kakkoyun, lcosic, mloibl, pkrupa, surbania
Target Milestone: ---   
Target Release: 4.3.z   
Hardware: Unspecified   
OS: Unspecified   
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Last Closed: 2020-02-24 08:42:50 UTC Type: ---
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Bug Depends On: 1794616    
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Description Sergiusz Urbaniak 2020-02-19 08:08:25 UTC 
This bug was initially created as a copy of Bug #1794616

I am copying this bug because: 



Description of problem:
we observed bunch of errors related to "caller=federate.go:184 component=web msg="federation failed" err="write tcp 127.0.0.1:9090->127.0.0.1:36894: write: broken pipe"" ( full log attached ) on a large scale 4.3 cluster ( 800 nodes ) built using 4.3.0-rc.3 payload. Looking at the logs, increasing the scrape_timeout and scrape_interval might help avoid this at large node counts. We are not exactly sure why the federation is enabled by default.

Version-Release number of selected component (if applicable):
OpenShift build/payload version: 4.3.0-rc.3

How reproducible:
We haven't seen this error before as we didn't really scale the cluster to large number of nodes.

Steps to Reproduce:
1. Build a cluster using 4.3.0-rc.3 payload.
2. Scale the cluster to larger node counts.
3. Look at one of the prom replica logs.

Actual results:
caller=federate.go:184 component=web msg="federation failed" err="write tcp 127.0.0.1:9090->127.0.0.1:36894: write: broken pipe"

Expected results:
Metrics scraped within the scrape_timeout interval.

Additional info:
Full logs are at http://dell-r510-01.perf.lab.eng.rdu2.redhat.com/4.3/logs/prometheus_scrape/