[Cbbackupmgr] - Backup fails while trying to communicate with the eventing backup end-point in an IPv6 only environment.

Description:

Backup fails while trying to connect to the eventing backup end-point in an IPv6 'only' environment.

Environment:

A single node IPv6 only guest running Centos 7.

Steps to reproduce:

1. Initialise a single node with all services except for analytics.
2. Load the travel-sample from the user-interface.
3. Create a backup repository using 'cbbackupmgr config'

   command
   [root@node1-cheshire-cat-testing-centos7 ~]# /opt/couchbase/bin//cbbackupmgr config --archive /tmp/my_archive --repo backup
   Backup repository `backup` created successfully in archive `/tmp/my_archive`

4. Take a backup using 'cbbackupmgr backup'

   command
   [root@node1-cheshire-cat-testing-centos7 ~]# /opt/couchbase/bin//cbbackupmgr backup --archive /tmp/my_archive --repo backup --cluster http://[fd5d:12c9:2201:1::101]:8091 --username Administrator --password password
   Backing up to '2021-02-11T12_34_19.113346478Z'
   Transferring eventing metadata 0 items / 0B
   [ ] 0.19%
   Error backing up cluster: connection refused

What happens:

The backup fails while trying to communicate with the full-text search backup end-point with the following error present in the logs:

2021-02-11T12:34:19.132+00:00 (Cmd) Error backing up cluster: failed to execute cluster operations: failed to transfer Eventing metadata: failed to get Eventing metadata: failed to get eventing metadata: failed to execute request: http client failed to dispatch/receive request/response: Get "http://[fd5d:12c9:2201:1::101]:8096/api/v1/backup": dial tcp [fd5d:12c9:2201:1::101]:8096: connect: connection refused

The logs:

backup-0.log

[^collectinfo-2021-02-11T124801-ns_1@127.0.0.1.zip]