dovecot: auth: Error: DNS lookup for xxx failed: Name does not resolve

[John Stoffel]

Marc> I am sure resolving works fine. I tested this in a running mesos
Marc> container, but also in docker run[1]. I need to have the search
Marc> local option in resolve.conf.

Marc> It was actually working, until I started adding the proxy for
Marc> managesieve, but when I reverted, it still does not work. I
Marc> think the building from cache mislead me.

Can you post more of the logs by any chance, especially from the
startup?  And are you sure you reverted all the config completely?  

Marc> I suspect this is a different problem, that at some point is
Marc> giving this error. Maybe I need some specific config for the
Marc> dns-client socket.

Maybe, I really don't know docker at all, or how to work with it.
Haven't had a need.

Marc> PS. This is just a proxy I need temporary. But I am thinking of
Marc> creating a container that directly connects to ceph storage so
Marc> you do not need any local storage.

That might do the trick, but I'd first just get the base install
working again, and maybe post your config from before and after so
people can get a better idea of what you're trying to do here. 

Marc> [1]
Marc> docker run --dns-search='local' -v /dev/log:/dev/log -it dovecot-proxy 
Marc> bash

Marc> [2]
Marc> passdb {
Marc>   driver = ldap
Marc>   args = /etc/dovecot/dovecot-ldap.conf.ext
Marc>   default_fields = proxy=y host=svr1
Marc> }

Marc> -----Original Message-----
Marc> From: John Stoffel [mailto:john at stoffel.org] 
Marc> Sent: zaterdag 30 november 2019 20:51
Marc> To: Marc Roos
Marc> Cc: dovecot
Marc> Subject: Re: dovecot: auth: Error: DNS lookup for xxx failed: Name does 
Marc> not resolve


Marc> I had a working container with dovecot configured as proxy. And 
Marc> all of a sudden I am getting these messages 'dovecot: auth:
Marc> Error: DNS lookup for roosit03 failed: Name does not resolve'
Marc> Pinging/nslookup these hostnames is ok

Marc> Does nslookup work inside the container?  Sounds to me like the setup 
Marc> isn't working properly, but it's hard to know unless you give us more 
Marc> details.  Can you spin up another container with the same config but not 
Marc> running dovecot to do a check on DNS resolution?

Marc> Does the container's logs give you more details?  How often do you 
Marc> stop/restart the container?  I would think that Dovecot in a container 
Marc> isn't really ideal since you need to access the mailstores, and somehow 
Marc> you get email delivered to the mailstore by postfix/sendmail/exim or 
Marc> some other tool.

Marc> John