Bug 1783352 - kcm doesn't work on IPv6
Summary: kcm doesn't work on IPv6
Alias: None
Product: OpenShift Container Platform
Classification: Red Hat
Component: kube-controller-manager
Version: 4.3.0
Hardware: Unspecified
OS: Unspecified
Target Milestone: ---
: 4.4.0
Assignee: Maciej Szulik
QA Contact: zhou ying
Depends On:
Blocks: 1783353
TreeView+ depends on / blocked
Reported: 2019-12-13 15:46 UTC by Maciej Szulik
Modified: 2020-05-13 21:55 UTC (History)
2 users (show)

Fixed In Version:
Doc Type: No Doc Update
Doc Text:
Clone Of:
: 1783353 (view as bug list)
Last Closed: 2020-05-13 21:55:16 UTC
Target Upstream Version:

Attachments (Terms of Use)

System ID Private Priority Status Summary Last Updated
Red Hat Product Errata RHBA-2020:0581 0 None None None 2020-05-13 21:55:18 UTC

Description Maciej Szulik 2019-12-13 15:46:20 UTC
Description of problem:
If you say net.Listen("tcp", ""), golang will actually create a dual-stack IPv4/IPv6 listening socket. But for historical reasons (having to do with bad IPv6 compat in older kube I think), we default to passing "tcp4" (the default value of configv1.ServingInfo.BindNetwork) instead of "tcp", forcing IPv4-only.

There is no reason these days for servers on the pod network to enforce IPv4-only, so this overrides the default for kube-controller-manager.

Comment 1 Maciej Szulik 2019-12-13 15:47:59 UTC
This was fixed in https://github.com/openshift/cluster-kube-controller-manager-operator/pull/320

Comment 3 zhou ying 2019-12-16 07:28:56 UTC
Confirmed with latest payload: 4.4.0-0.nightly-2019-12-15-184910, the issue has fixed:

Login the master node, check the Listen port:

[root@dhcp-140-138 ~]# oc debug node/ip-xxxxx
Starting pod/ip-10-0-130-121us-east-2computeinternal-debug ...
To use host binaries, run `chroot /host`
Pod IP:
If you don't see a command prompt, try pressing enter.
sh-4.2# chroot /host
sh-4.4# netstat -pan |grep 10357
tcp6       0      0 :::10357                :::*                    LISTEN      51788/cluster-polic

Comment 5 errata-xmlrpc 2020-05-13 21:55:16 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.


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