Priority: Major - P3
Affects Version/s: None
Fix Version/s: 4.5.1
Steps To Reproduce:
Using a configuration file with
disabling IPv6 in the system by running
it works fine, but disabling it passing
as a bootarg to the Linux kernel, we obtain the
error message in the logs and the service doesn't run.Using a configuration file with net: ipv6: true disabling IPv6 in the system by running sudo sysctl -w net.ipv6.conf.*.disable_ipv6= 1 it works fine, but disabling it passing ipv6.disable= 1 as a bootarg to the Linux kernel, we obtain the 2019 - 06 -21T14: 09 : 17.995 + 0000 I STORAGE [initandlisten] exception in initAndListen std::exception: open: Address family not supported by protocol, terminating error message in the logs and the service doesn't run.
Sprint:Service Arch 2019-10-07, Service Arch 2019-10-21, Service Arch 2019-11-18, Service Arch 2019-12-02, Service Arch 2019-12-16, Service Arch 2019-12-30, Service Arch 2020-01-13, Service Arch 2020-01-27, Service Arch 2020-02-10, Service Arch 2020-03-23
Tested on k8s by setting the ipv6 parameter to true or false in the mongodb.conf file:
In some k8s cluster, mongodb service is not running because of the following error (from mongodb.log):
This message is very descriptive:
Although the host has disabled IPv6, it is expected that MongoDB will try to use IPv4 in its absence, in fact, we tried it when using this parameter for the first time, so why in some k8s cluster works and not in others?
We can disable IPv6 support by running
in this case, mongodb server does not complain about unsupported address family when IPv6 is enabled in the configs. This reflects with our earlier findings as we had used the same method to disable IPv6.
Continuing on our investigation, we found that the alternate way of disabling IPv6 support is to pass
as a bootarg to the Linux kernel and with this, we were able to see the unsupported address family error with mongodb.
With these findings, we cannot make the assumption that IPv6 enabled in the mongodb configs by default will always work regardless of whether the underlying host supports IPv6 or not.