failed: read(/var/run/dovecot/dns-client)

[Aki Tuomi]

> On 10 April 2019 21:26 Laura Smith via dovecot <dovecot at dovecot.org> wrote:
> 
>  
> ===
> dsync(foobar at example.com): Error: imapc(foobar.example.com:993): dns_lookup(foobar.example.com) failed: read(/var/run/dovecot/dns-client) failed: read(size=512) failed: Connection reset by peer
>

This is dovecot's internal dns-client, and something goes wrong when talking to the service.
 
> dsync(foobar at example.com): Error: Failed to initialize user: imapc: Login to foobar.example.com failed: Disconnected from server

This is btw dsync service, not imap service.

> ===
> 
> Initially I thought "oh no, not another AppArmor block".
> 
> But then surely the second message would not appear if the DNS lookup was not successful ?
> 
> Also "dig foobar.example.com" works fine.
> 
> How should I be troubleshooting this ?  And if it is still likely to be AppArmor, what is calling it ? "doveadm" itself or something else ?  What does "/var/run/dovecot/dns-client" do and why doesn't dovecot use standard OS calls like everyone else ?
> 

Because the "standard OS call" is blocking and we would prefer it to not block everything else.

> So many questions !

Aki