Cannot resolve .. [Errno -2] Name or service not known

[ksarabu1]

Fixes #

Why is this needed?

Zookeeper is running from Docker containers and the service being resolved using Consul. When there's a network issue, the call to socket.getaddrinfo in method _expand_client_hosts causing it to return the error Cannot resolve .. [Errno -2] Name or service not known. This is causing retry to throwback STOP_CONNECTING and it stops retrying as result.

Proposed Changes

Change: Raise ForceRetryError if method _expand_client_hosts returns empty host/ports and client.hosts has only one host to resolve.

        # Check for an empty hostlist, indicating none resolved
        if len(host_ports) == 0:
            if len(self.client.hosts) == 1:
                raise ForceRetryError('Reconnecting')
            return STOP_CONNECTING

Does this PR introduce any breaking change?

n/a

[StephenSorriaux]

Would you be willing to explain the reason for this additional condition? Looking at the code, I would have replaced the return STOP_CONNECTING with a raise ForceRetryError('No host resolved, reconnecting') but you may have seen something I am missing.

[ksarabu1]

Thanks. I was just trying to keep the behavior to default when multiple hosts are used and if they all fail to resolve. I would also prefer to keep it simple and raise retry in all cases. Will update.

[StephenSorriaux]

Thans for this PR.

Overall I am fine with the idea behind the change, it makes sense to trigger the retry policy in case hosts are not resolved.

[ceache]

I second @StephenSorriaux's feedback. The idea is good but I am confused by the additional check on a single host in the list.

[StephenSorriaux]

Thank you.

[ksarabu1]

@ceache Can you please review. Thanks

[ceache]

Thanks!

[ksarabu1]

Thank you. Can you please merge the PR? Thanks in advance.