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Bug 1208834 - Negative DNS caching causes troubles for go binaries
Summary: Negative DNS caching causes troubles for go binaries
Keywords:
Status: CLOSED NOTABUG
Alias: None
Product: Red Hat Enterprise Linux 7
Classification: Red Hat
Component: golang
Version: 7.1
Hardware: x86_64
OS: Linux
unspecified
medium
Target Milestone: rc
: ---
Assignee: Jakub Čajka
QA Contact: qe-baseos-tools-bugs
URL:
Whiteboard:
Depends On:
Blocks: 1189840
TreeView+ depends on / blocked
 
Reported: 2015-04-03 11:08 UTC by Michal Minar
Modified: 2016-06-14 09:15 UTC (History)
2 users (show)

Fixed In Version:
Doc Type: Bug Fix
Doc Text:
Clone Of:
Environment:
Last Closed: 2016-06-14 09:15:24 UTC
Target Upstream Version:
Embargoed:

Attachments (Terms of Use)
go reproducer (1.44 KB, text/plain)
2015-04-03 11:08 UTC, Michal Minar 		no flags Details
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Description Michal Minar 2015-04-03 11:08:49 UTC 
Created attachment 1010599 [details]
go reproducer

Description of problem:
  Golang binaries remember failed attempts of domain name resolutions and fail again after the connection is restored.

Version-Release number of selected component (if applicable):
  golang-1.3.3-3.el7

How reproducible:
  In one of two cases.

Steps to Reproduce:
1. Make sure networking is deconfigured - no IPv4 address on the primary $NIC
2. docker pull fedora
3. nmcli d connect $NIC
4. docker pull fedora

Actual results:
  'docker pull' doesn't resolve index.docker.io even if the internet connection is restored. ping index.docker.io works well

Expected results:
  'docker pull' works as soon as the internet connectivity is restored after failing first

Additional info:
  Fedora rawhide does not suffer from this issue. I've tried to compile rawhide's golang (1.4.2) on RHEL7 only to find out that it behaves a little bit better (fails in 1 case out of 4) which it's still quite bad.
  Attached is a simple go reproducer that tries to ping url, brings interface down, pings again, brings interface up and pings once again. The 3rd attempt should never fail.
  The same reproducer written in python doesn't fail (will be attached later). Therefore I believe this is somehow related to golang.
Comment 1 Michal Minar 2015-04-03 11:10:09 UTC 
Python reproducer is attached to parent bug: https://bugzilla.redhat.com/attachment.cgi?id=1010593
Comment 5 Jakub Čajka 2016-06-14 09:15:24 UTC 
I have been unable to reproduce this issue using the attached reproducer on RHEL-7.2 with golang-1.4.2-9.el7. Feel free to reopen this bug with more information, if your issue still persists.
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