Bug #86858 Confusing GR error message: check credentials, but issue is hostnanme resolving
Submitted: 29 Jun 2017 3:19 Modified: 8 Sep 2017 14:54
Reporter: Jesper wisborg Krogh Email Updates:
Status: Closed Impact on me:
None 
Category:MySQL Server: Group Replication Severity:S2 (Serious)
Version:5.7.18 OS:Any
Assigned to: CPU Architecture:Any

[29 Jun 2017 3:19] Jesper wisborg Krogh
Description:
If hostname resolution does not work for a member in Group Replication, the error returned when attempting to connect is:

2017-06-29T00:56:02.103512Z 23 [ERROR] Plugin group_replication reported: 'There was an error when connecting to the donor server. Check group replication recovery's connection credentials.'

But the issue has nothing to do with credentials, but the fact that Group Replication only works when the hostname/IP address is resolvable.

See also Bug 25260855 and Bug 25243064

How to repeat:
Setup Group Replication on hosts that doesn't have resolvable hostnames and IP addresses. E.g. ad hoc VMs in VirtualBox. Then start Group Replication on the first member, and finally attempt on a second member. The second member will fail to join with the above error message.

Suggested fix:
Change the error message to make it clear that it is the hostname resolution within Group Replication that is not working and this is a requirement.
[8 Sep 2017 14:54] David Moss
Posted by developer:
 
This doesn't seem to have a user impact, closing without changelog entry.
[18 Sep 2017 9:44] David Moss
Posted by developer:
 
Thank you for your feedback, this has been fixed in upcoming versions and the following was added to the 5.7.20 / 8.0.3 changelog:
If hostname resolution was not working for a member in Group Replication, the error returned when attempting to connect was referring to credentials. The error message has been improved to describe the problem with hostname resolution.